Natural Hazard Mitigation Plan 2019 Revision
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Nez Perce Tribe
Natural Hazard Mitigation Plan 2019 Revision
Nez Perce Tribe Emergency Management
Box 365 – 109 Lolo St
Lapwai ID 83540
(208) 621-3760
Prepared By
Northwest Management, Inc.
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Nez Perce Tribal Emergency Management is dedicated to the protection of life, property,
economic and environmental resources throughout the Reservation. Seeking to inform and
educate citizens, provide training and resource coordination and ultimately reduce the
vulnerability of Tribal citizens through comprehensive disaster planning and mitigation.
“Hazard mitigation is sustained action to reduce or eliminate the long‐term risk to human life
and property from hazards. Natural hazard mitigation planning is a process used by state, tribal,
and local governments to engage stakeholders, identify hazards and vulnerabilities, develop a
long-term strategy to reduce risk and future losses, and implement the plan, taking advantage
of a wide range of resources. A state mitigation plan demonstrates commitment to reduce risks
from natural hazards and serves as a guide for decision makers for reducing the effects of
natural hazards as resources are committed”1
The Nez Perce Tribe Natural Hazard Mitigation Plan was updated in 2017-19 by the Nez Perce
Tribe Hazard Mitigation Steering Committee in cooperation with Northwest Management, Inc.
of Moscow, Idaho. This Plan satisfies the requirements for a local natural hazard mitigation plan
under 44 CFR Part 201.6, in addition this plan fully integrated the processes of FEMA’s Natural
Hazard Mitigation Plan with the Community Wildfire Protection Plan as outlined in the Healthy
Forest Restoration Act.
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Federal Emergency Management Agency. “Local Multi-Hazard Mitigation Planning Guidance.” July 1, 2008
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Table of Contents
CHAPTER 1 ............................................................................................................................ 1
Background ....................................................................................................................................1
Goals and Guiding Principles...........................................................................................................2
HMP Mission Statement ......................................................................................................... 2
Federal Emergency Management Agency Philosophy ........................................................... 2
Plan Overview ................................................................................................................................4
Update and Adoption Requirements ...............................................................................................5
CHAPTER 2 ............................................................................................................................ 7
Plan Update Process .......................................................................................................................7
Tribal Involvement .................................................................................................................. 8
Public Involvement ................................................................................................................. 9
Incorporation of Existing Plans ............................................................................................. 10
Plan Maintenance ........................................................................................................................ 11
Evaluating and Updating the Plan ......................................................................................... 11
Obtaining Continued Public Involvement ............................................................................. 12
CHAPTER 3 .......................................................................................................................... 13
History and Description of the Reservation ................................................................................... 13
Government .......................................................................................................................... 16
Demographics ....................................................................................................................... 16
Land Use and Development Trends ...................................................................................... 16
CHAPTER 4 .......................................................................................................................... 18
Risk Assessment Overview ........................................................................................................... 18
Flood Hazard Profile ..................................................................................................................... 20
Hazard Description and History ............................................................................................ 20
Probability of Future Occurrence ......................................................................................... 24
Impacts of Flood Events ........................................................................................................ 27
Value of Resources at Risk .................................................................................................... 31
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Severe Weather Hazard Profile ..................................................................................................... 33
Drought ................................................................................................................................. 34
Hailstorms ............................................................................................................................. 37
Windstorms ........................................................................................................................... 39
Winter Storms ....................................................................................................................... 41
Landslide Hazard Profile ............................................................................................................... 45
Hazard Description and History ............................................................................................ 45
Probability of Future Occurrence ......................................................................................... 47
Impacts of Landslide Events.................................................................................................. 48
Value of Resources at Risk .................................................................................................... 48
Wildland Fire Profile ..................................................................................................................... 50
Wildland Fire Characteristics ................................................................................................ 50
History and Extent................................................................................................................. 52
Wildland Fire Risk.................................................................................................................. 57
Volcanic Eruption Profile .............................................................................................................. 69
Hazard Description and History ............................................................................................ 69
Probability of Future Occurrence ......................................................................................... 72
Impacts of Volcanic Eruption ................................................................................................ 73
Value of Resources at Risk .................................................................................................... 74
Hazardous Materials .................................................................................................................... 75
Hazard Description and History ............................................................................................ 75
Probability of Future Occurrence ......................................................................................... 76
Impacts of Hazardous Materials Release .............................................................................. 77
Values of Resources at Risk .................................................................................................. 77
Vulnerable Areas and Infrastructure ............................................................................................. 80
Residential Structures ........................................................................................................... 81
Critical Infrastructure ............................................................................................................ 83
Cultural and Sacred Sites ...................................................................................................... 85
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CHAPTER 5 .......................................................................................................................... 86
Mitigation Strategy ...................................................................................................................... 86
Mitigation Goals .................................................................................................................... 86
Mechanisms to Incorporate Mitigation Strategies ............................................................... 87
Development of Mitigation Action Items ............................................................................. 87
2019 Mitigation Action Items ............................................................................................... 90
Capability Assessment .......................................................................................................... 97
Funding Sources .................................................................................................................... 99
APPENDICES ...................................................................................................................... 102
Appendix 1 – Agendas and Sign-in Sheets ................................................................................... 102
Committee Involvement Documentation ........................................................................... 102
Public Involvement Documentation ................................................................................... 107
Record of Survey Respondents ........................................................................................... 111
Appendix 2 – Future Plan Update Guidelines............................................................................... 112
Appendix 3 – Maps with Legends Included .................................................................................. 115
Reservation Location and Land Ownership ........................................................................ 116
Demographics ..................................................................................................................... 117
Land Use .............................................................................................................................. 118
Location of Residential Structures ...................................................................................... 119
Locations of Critical Facilities .............................................................................................. 120
Hazardous Materials Facilities and Transportation ............................................................ 121
Potential Flood Area ........................................................................................................... 122
Dam Failure and Inundation Zones ..................................................................................... 123
Landslide Risk Areas ............................................................................................................ 124
Wildfire Risk ........................................................................................................................ 125
Wildfire History ................................................................................................................... 126
Locations of Active Volcanos .............................................................................................. 127
Appendix 4 – FEMA HMP Requirements ...................................................................................... 128
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Acronyms
AFG
ANA
DMA 2000
CFR
cfs
EHS
EPA
EPCRA
FEMA
FIRM
FIS
FMA
GIS
HMGP
HMP
IDWR
NFIP
NPT
NPTEC
PDM
Reservation
SFHA
Stafford Act
HMP Committee
Tribe
NMI
Assistance to Firefighters Grant
Administration for Native Americans
Disaster Mitigation Act of 2000
Code of Federal Regulations
cubic feet per second
Extremely Hazardous Substance
U.S. Environmental Protection Agency
Emergency Planning and Community Right to Know Act
Federal Emergency Management Agency
Flood Insurance Rate Map
Flood Insurance Study
Flood Mitigation Assistance
Geographic Information System
Hazard Mitigation Grant Program
Hazard Mitigation Plan
Idaho Department of Water Resources
National Flood Insurance Program
Nez Perce Tribe
Nez Perce Tribal Executive Committee
Pre-Disaster Mitigation grant program
Nez Perce Reservation
Special Flood Hazard Area
Robert T. Stafford Disaster Relief and Emergency Assistance Act
Hazard Mitigation Planning HMP Committee
Nez Perce Tribe
Northwest Management Inc.
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Chapter 1
Background
Natural hazards are inherent properties of the Earth that can influence and impact both living
and non-living features of the natural environment. Natural hazards vary in scale and potential
impact; localized windstorms are capable of damaging and uprooting individual trees while
volcanic eruptions can impact or destroy hundreds of square miles of terrain and cause
widespread mortality of plants and animals. Certain types of natural disasters are far more
common in some regions of the United States than in others. The Pacific Northwest is
associated with wildfire, earthquake, and volcanic hazards; the central plains often experience
severe storms that are capable of producing tornados up to one mile wide; while the Atlantic
coast is periodically exposed to tropical storms and hurricanes.
These different landscapes are resilient in the face of a natural disaster but humans and human
development are much less so. Humans have always lived with the consequences of natural
disasters which often include displaced residents, loss of property, costly clean up and repairs,
and lost time which is often measured in years. In response to increasing populations and
expansion of development, communities are identifying steps that can be taken to mitigate the
impacts of natural hazards. Mitigation measures are preventative actions that make
communities and individuals more resilient to natural hazards and reduce the cost of recovery.
The goal of this document is to accurately identify risks to the people and property on the Nez
Perce Reservation and provide a plan for mitigation efforts in accordance with the Disaster
Mitigation Act of 2000. The Federal Emergency Management Agency (FEMA) provides funding
opportunities for mitigation actions and requires a hazard mitigation plan (HMP) that identifies
risks and vulnerabilities, proposes mitigation strategies and a planning process that includes
multi-jurisdictional participation along with public outreach. Additionally, the HMP Committee
desires to create a document that is easy to use, actively referenced and is a key component in
making the Nez Perce Reservation more resilient to natural hazards.
This Reservation-wide Hazard Mitigation Plan is the result of analyses, professional cooperation
and collaboration, assessments of hazard risks and other factors considered with the intent to
reduce the potential threat posed by natural hazards to people, structures, infrastructure, and
unique ecosystems on the Nez Perce Reservation. The Nez Perce Hazard Mitigation Plan was
originally approved by Idaho Office of Emergency Management and FEMA in 2006 and was
updated in 2009 and again in 2019. This document serves as an update of the Multi-Hazard
Mitigation Plan under the Pre-Disaster Mitigation program and will be in effect until 2022. This
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document assists with the identification and assessment of various potential hazards and helps
maintain the Tribe’s eligibility for grants and other funding.
The Multi - Hazard Mitigation Plan is developed in accordance with the requirements of FEMA
and the Idaho Office of Emergency Management for a reservation-level pre-disaster mitigation
plan. The State of Idaho Hazard Mitigation Plan identifies seven natural hazards affecting the
State. In an effort to be consistent, the Steering Committee chose six natural hazard annexes
from the state-identified natural hazards that pose the highest risk for the Tribe. The hazardous
materials annex from the previous plan will also be carried over to this plan.
The hazards annexes that will be updated for this plan include:
✓ Flood
✓ Severe Weather
✓ Landslide
o Drought
✓ Volcanic Eruption
o Hailstorm
✓ Wildland Fire
o Windstorm
It should be noted that the planning committee decided to exclude earthquake as a separate
hazard in the plan as the Reservation is in a relatively stable seismic zone. Although geologists
have discovered several regional faults and acknowledge the potential for earthquakes as a
result of volcanic activity, earthquakes are considered a low-level threat to life and property on
the Nez Perce Reservation due to the low probability of occurrence; mirroring sentiments of
the 2006 and 2009 versions of the HMP.
Goals and Guiding Principles
HMP Mission Statement
To make Tribal residents, communities, and businesses less vulnerable to the effects of natural
and man-made hazards through the effective administration of hazard mitigation grant
programs, hazard risk assessments, wise and efficient infrastructure construction and
placement, and a coordinated approach to mitigation policy through federal, state, regional,
and local planning efforts. Our combined prioritization will be the protection of people,
structures, infrastructure, and unique ecosystems that contribute to our way of life and the
sustainability of the local and regional economy.
Federal Emergency Management Agency Philosophy
Effective November 1, 2004, a Natural Hazard Mitigation Plan approved by the Federal
Emergency Management Agency (FEMA) is required for Hazard Mitigation Grant Program
(HMGP) and Pre-Disaster Mitigation Program (PDM) eligibility. The HMGP and PDM programs
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provide funding, through state emergency management agencies, to support local mitigation
planning and projects to reduce potential disaster damages.
The new local Natural Hazard Mitigation Plan requirements for HMGP and PDM eligibility is
based on the Disaster Mitigation Act of 2000, which amended the Stafford Disaster Relief Act to
promote an integrated, cost effective approach to mitigation. Local Natural Hazard Mitigation
Plans must meet the minimum requirements of the Stafford Act-Section 322, as outlined in the
criteria contained in 44 CFR Part 201. The plan criteria cover the planning process, risk
assessment, mitigation strategy, plan maintenance, and adoption requirements.
FEMA will only review a Tribal Natural Hazard Mitigation Plan adopted by the tribal
governing body §201.7(c)(5). Draft versions of local Natural Hazard Mitigation Plans will not be
reviewed by FEMA. FEMA will review the final version of a plan prior to local adoption to
determine if the plan meets the criteria, but FEMA will be unable to approve it prior to
adoption.
A FEMA designed plan will be evaluated on its adherence to a variety of criteria, including:
•
Adoption by the Tribal Governing Body
•
Multi-jurisdictional Plan Adoption
•
Multi-jurisdictional Planning Participation
•
Documentation of Planning Process
•
Identifying Hazards
•
Profiling Hazard Events
•
Assessing Vulnerability: Identifying Assets
•
Assessing Vulnerability: Estimating Potential Losses
•
Assessing Vulnerability: Analyzing Development Trends
•
Multi-jurisdictional Risk Assessment
•
Local Hazard Mitigation Goals
•
Identification and Analysis of Mitigation Measures
•
Implementation of Mitigation Measures
•
Multi-jurisdictional Mitigation Strategy
•
Monitoring, Evaluating, and Updating the Plan
•
Implementation Through Existing Programs
•
Continued Public Involvement
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Plan Overview
Plan Update Process (Chapter 2) describes the process by which the plan will be updated and
maintained once it is adopted. This includes both committee and community involvement in all
stages of the process.
The following outlines the planning process as described in §201.7(c)(1):
(i) An opportunity for the public to comment on the plan during the drafting stage and
prior to plan approval, including a description of how the Tribal government defined
“public;”
(ii) As appropriate, an opportunity for neighboring communities, tribal and regional
agencies involved in hazard mitigation activities, and agencies that have the authority to
regulate development, as well as businesses, academia, and other private and nonprofit
interests to be involved in the planning process;
(iii) Review and incorporation, if appropriate, of existing plans, studies, and reports; and
(iv) Be integrated to the extent possible with other ongoing tribal planning efforts as
well as other FEMA programs and initiatives.
Chapter 2 also describes the HMP Committee’s formal plan maintenance process to ensure that
the HMP remains an active and applicable document. The process includes monitoring,
evaluating, and updating the HMP, monitoring the mitigation measures and project closeouts,
and incorporating public input throughout the HMP’s 5-year lifespan.
History and description of the Reservation (Chapter 3) provides a general history and
background of the Tribe and historical trends for population, demographic, and economic
conditions that have shaped the area. Trends in land use and development are also discussed.
For public participation in the planning process the Tribal Government defines “public” as
current Tribal members.
Risk Assessment Overview (Chapter 4) details the process of identifying hazards and describes
the process through which the HMP Committee identified and compiled relevant data on all
potential natural hazards that threaten the Reservation and the immediately surrounding area.
Information collected includes historical data on natural hazard events that have occurred in
and around the Reservation and how these events impacted tribal members and their property.
The descriptions of natural hazards that could affect the Reservation are based on historical
occurrences and best available data from agencies such as FEMA, the U.S. Geological Survey,
the Idaho Geologic Survey, and the National Weather Service. Detailed hazard profiles include
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information on the frequency, magnitude, location, and impact of each hazard as well as
probabilities for future hazard events.
In addition, Chapter 4 identifies potentially vulnerable assets such as people, housing units,
critical facilities. These data were compiled by assessing the potential impacts from each hazard
using U.S. Census data, and the Nez Perce Tribe Land Services Program and Housing Authority,
and GIS. The resulting information identifies the full range of hazards that the Reservation could
face and potential social impacts, damages, and economic losses.
Mitigation Strategy (Chapter 5) first provides an overview of the Tribe’s resources in the
following areas for addressing hazard mitigation activities:
•
Existing ordinances, plans, and codes that affect the physical or built environment
•
The current and potential financial resources to implement the mitigation strategy
Chapter 5 also describes the process in which the HMP Committee:
•
Verified mitigation goals based upon the findings of the risk assessment and the
capability assessment
•
Reevaluated a comprehensive range of appropriate mitigation actions from the 2009
HMP
•
Reconfirmed mitigation actions to be included in the 2019 HMP’s Action Plan
The appendices include the Adoption Resolution, maps and figures, HMP Committee agendas,
and public involvement process.
Update and Adoption Requirements
Adoption by the governing body demonstrates a community’s commitment to fulfilling the
mitigation goals and objectives outlined in the HMP. Adoption legitimizes the HMP and
authorizes responsible agencies to execute their responsibilities. Following adoption by the Nez
Perce Tribal Council, the plan was reviewed and approved by the Idaho Office of Emergency
Management and FEMA. A copy of the resolution, adopted by the NPTEC, assures FEMA that
the Tribe will comply with both of the CFR requirements. The resolution is presented in
Appendix 2.
The following is a brief summary of the plan update requirements for Tribes:
•
Deadlines and Requirements for Regular Plan Reviews and Updates: In order to apply for
a FEMA PDM project grant, Tribal and local governments must have a FEMA-approved
mitigation plan. Tribal and local governments must have a FEMA-approved mitigation
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plan in order to receive HMGP project funding for disasters declared on or after
November 1, 2004. States and Tribes must have a FEMA-approved Standard or
Enhanced Mitigation Plan in order to receive non-emergency Stafford Act assistance
(i.e., Public Assistance Categories C-G, HMGP, and Fire Management Assistance Grants)
for disasters declared on or after November 1, 2004. State mitigation plans must be
reviewed and reapproved by FEMA every three years. Local Mitigation Plans must be
reviewed and reapproved by FEMA every five years.
•
Plan updates. In addition to the timelines referenced above, the Rule includes the
following paragraphs that pertain directly to the update of State, Local, and Tribal plans;
o §201.3(b)(5) [FEMA Responsibilities] …Conduct reviews, at least once every
three years, of State mitigation activities, plans, and programs to ensure that
mitigation commitments are fulfilled….
o §201.7(c)(4) [Indian tribal governments] …A system for reviewing progress on
achieving goals as well as activities and projects identified in the mitigation
strategy.
o §201.7(d)(3) [Tribal] must review and revise their plan to reflect changes in
development, progress in local mitigation efforts, and changes in priorities, and
resubmit it for approval within 5 years in order to continue to be eligible for nonemergency Stafford Act assistance and FEMA mitigation grant funding, with the
exception of the Repetitive Flood Claims program.
Plan updates must include a system for reviewing the progress on mitigation activities that
were identified within the plan. This will involve a comprehensive review and evaluation of
each section of the plan and a discussion of the results of evaluation and monitoring activities
detailed in the Plan Maintenance section of the previously approved plan. Updates to the plan
may validate the information in the previously approved plan, or may involve a major plan
rewrite. In any case, a plan update is NOT an annex to the previously approved plan; it must
stand on its own as a complete and current plan.
The objective of combining these complementary guidelines is to facilitate an integrated
wildland fire risk assessment, identify pre-hazard mitigation activities, and prioritize activities
and efforts to achieve the protection of people, structures, the environment, and significant
infrastructure on the Nez Perce reservation while facilitating new opportunities for pre-disaster
mitigation funding and cooperation.
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Chapter 2
Documentation of the planning process, including public involvement, is required to meet
FEMA’s DMA 2000 (44CFR§201.7(b) and §201.7(c)(1)) for an updated local mitigation plan. This
section includes a description of the planning process used to update this plan, including how it
was prepared, who was involved in the process, and how involved agencies participated.
Plan Update Process
The Tribal Multi - Hazard Mitigation Plan was developed through a collaborative process with
outreach to many of the organizations within the jurisdictional boundaries of Tribal lands. Nez
Perce Tribe Emergency Management invited stakeholders to planning meetings throughout the
planning process, including personnel from wildlife management, historical preservation,
forestry and fire, emergency management, air quality, and others. The planning effort began by
organizing and convening a Tribal Steering Committee that incorporated all departments of the
Tribal Government as well as outside agencies and neighboring jurisdictions.
The Tribe utilized members of the Tribal Emergency Response Planning Team (TERPT) to
develop the Hazard Mitigation Plan Committee and begin the update process. HMP Committee
meetings began in July of 2017, with meetings held in October, December, January, and March.
The planning process included seven distinct steps which were in some cases sequential (step 1
then step 2) and in some cases intermixed (step 5 completed throughout the process):
1. Organization of Resources – The Tribe and Northwest Management Inc. (NMI) worked
together to develop a comprehensive list of potential participants as well as a project
timeline and work plan. The HMP Committee served as the basis for identifying
stakeholders that could provide valuable insight into risk assessments and mitigation
strategies during the update process.
2. Collection of Data – Nez Perce Tribal GIS Department collected all data performed in the
risk assessment and ancillary data for background information.
3. Field Observations and Estimations –Nez Perce Tribal GIS Department developed risk
models and identified problem areas in order to better understand risks, juxtaposition
of structures and infrastructure to risk areas, access, and potential mitigation projects.
Many of the analyses used in the 2009 plan were reviewed and updated to incorporate
new hazard vulnerabilities or changes in development. Additionally, several new risk
models and analyses were included in the 2017-19 update process to better represent
actual conditions on the Reservation.
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4. Mapping – Nez Perce Tribal GIS Department developed mapping products as visual tools
to support various analyses. All of the maps and databases were updated as part of the
2019 plan update.
5. Public Involvement – the HMP committee with NMI developed a plan to involve the
public from the formation of the committee through public meetings and workshops,
public review of draft documents, and acknowledgement of the final updated plan by
the signatory representatives.
6. Strategies and Prioritization – NMI and the HMP Committee representatives worked
together to review the risk analyses and develop realistic mitigation strategies. As part
of the 2019 plan update, a record of completed action items as well as a status report of
projects was included in the revised mitigation strategies for each jurisdiction.
7. Drafting of the Report – NMI drafted a final updated report document and worked with
members of the planning team to review each section, incorporate public comments,
proceed with the state and federal review processes, and adopt the final document.
Tribal Involvement
Individuals that were a part of the HMP Committee, their roles within the planning team, and
the jurisdiction they represent are highlighted in Table 1. The HMP Committee made efforts to
include individuals, tribal departments, outside state and federal agencies, neighboring
counties, and others that have an interest in hazard management on the Reservation.
Table 1) Nez Perce Reservation HMP Steering Committee members.
Name
Department & Title
Role in the Planning Process
John Wheaton
Emergency Management, EM Planner
Project Coordinator
Aaron Miles Sr.
Natural Resources, Manager
EOC Wildland Fire Experience
Alexis Walker
Human Resources, Risk Management
Personnel and Building Safety
Anthony Broncheau
Finance, Grants Coordinator
Finance Review
Antonio Smith
ERWM, Communications Specialist
Public Information Officer Alt.
Danae Wilson
Information Technology, Director
Interoperability
Darren Williams
Legal, Attorney
Provided policy and legal information
Dave Arther
NMPH, Nurse
Update Health Information
Dave Johnson
Fisheries, Manager
Fisheries protection and resources
Dean Neufeld
Public Health, Emergency Management
Training and Public Health Expertise
Debbie Henry
Former Safety Coordinator
Critical Infrastructure Safety
Ferris Paisano
NPT Executive Committee Law and Order Chair
Emergency Management Rep.
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Name
Department & Title
Role in the Planning Process
Jack Bell
ERWM, Director
Damage Assessment
Jackie McArthur
Social Services, Director
Vulnerable Populations
Jeff Handel
Forestry and Fire Management (FFM), FMO
Wildland fire expert
Julie Simpson
Air Quality Program, Coordinator
Weather and air quality expertise
Kayeloni Scott
Communications Director
Communications Expertise
Keith Baird
Tribal Historic Preservation
Cultural Analysis
Ken Clark
Water Resources, Director
Waterways expertise
Kerey Barnowe-Meyer
Wildlife Biologist
Integrated Resources Planning
Kim Cannon
Land Services, Director
Tribal Lands Expertise
Kip Kemak
FFM, Fire Prevention Specialist
Wildland fire expert
Laurie Ames
GIS Department, Coordinator
Mapping & risk analysis
Laurie Ann Cloud
Housing, Manager
Housing Assistance
Mark Reaney Jr.
NMPH, Facilities Manager
Health Facilities Expertise
Marty Antone
NPT Chief of Police
Law Enforcement
Neil Thagard
Wildlife, Director
Wildlife Expertise
Rebecca Miles
Nez Perce Tribe, Executive Director
Coordinates Logistics
Rob Feeley
Idaho Office of Emergency Management, AFO
State Resources Expertise
Ryan Bender
Public Health, Specialist
Coordinated trainings and plans
Stefanie Krantz
Water Resources, Climate Change Coordinator
Provide information on the influence
of climate change to hazards.
Tim Droegmiller
FFM, Acting Fuels Specialist
Provide information on the current
fuels conditions across the
Reservation.
Mark Corrao
Northwest Management Inc.
Project Lead for NMI
Tera King
Northwest Management Inc.
Project Support for NMI
Eric Nelson
Northwest Management Inc.
Project Support for NMI
John Degroot
Public Involvement
Public involvement in this plan was made a priority from the inception of the project. There
were a number of ways that public involvement was sought and facilitated. In some cases, this
led to members of the public providing information and seeking an active role in protecting
their own homes and businesses, while in other cases it led to the public becoming more aware
of the process without becoming directly involved in the planning.
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Nez Perce Tribe Emergency Management and NMI worked together to develop a brochure to
help educate and inform the public on the process the HMP Committee was involved in and
what that meant for Tribal members. Two public meetings were used to facilitate information
sharing to the public on the various risk analyses and mitigation action items. During these
meetings, discussions were led and forms were provided to help gather feedback about the
plan components and emergency management issues in general.
The workshops were held in the following locations:
•
Public Workshop #1 was an evening meeting hosted at the Wa-A’Yas Community Center
in Kamiah.Public
•
Workshop #2 was a full day event held at the Clearwater Casino near Lapwai.
Following the approval by the HMP committee and NPTEC of the draft document, a period of
public comment was provided to further incorporate input on the process and results of the
updated Hazard Mitigation Plan.
Incorporation of Existing Plans
During the planning process, and in particular when preparing the hazard analysis and
vulnerability analysis, the HMP Committee consulted various hazard and mitigation-related
plans and studies, including the following:
1.
Nez Perce Tribe Hazard Mitigation Plan (2009): Review of the previous HMP
provided a base for reviewing and updating community profiles, hazards, risks, and
mitigation action progress.
2.
Nez Perce Reservation Emergency Operations Plan: The Nez Perce Reservation
Emergency Operations Plan outlines the policies and concepts that guide response
at the local level in response to, and recovery from natural and man-caused
disasters. The Emergency Operations Plan describes an array of tribal responses and
efforts to save lives, limit human suffering, and protect public health, safety, and
property, including wildlife, natural resources, the environment, and local economy
from the damaging effects of natural and man-caused disaster emergencies.
3.
Idaho County, Idaho Multi-Hazard Mitigation Plan (2015): The Idaho County HMP
was referenced for updating hazard profiles and potential mitigation efforts that
may overlap with Tribal mitigation strategies. Other counties that fall within the
Reservation were in the process of updating their Hazard Mitigation Plans and were
therefore not reviewed.
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After the adoption of the HMP, the Steering Committee will ensure that elements of the HMP
are incorporated into other existing planning mechanisms. The processes for incorporating the
HMP into various planning documents will occur as (1) other plans are updated and (2) new
plans are developed. Accordingly, the Steering Committee will ensure that:
•
As the Emergency Operations Plan is updated, mitigation action 2.D (emergency
evacuation programs) is addressed.
•
As the Hazard Analysis Priorities is updated, mitigation action 3.B (dam inundation
maps) is addressed.
•
New GIS hazard and asset information from the HMP is integrated into the Tribe’s
GIS program.
Plan Maintenance
Evaluating and Updating the Plan
The HMP update was prepared as a collaborative effort among Tribal members on the Steering
Committee. The Tribe will continue to use the Steering Committee to monitor, evaluate, and
update the HMP. The Emergency Management Coordinator (Steering Committee leader) will
serve as the primary point of contact and will coordinate all local efforts to monitor, evaluate,
and revise the HMP.
Over the past three years, the HMP has not been reviewed. In order to ensure that the HMP
will be reviewed on an annual basis, a more streamlined plan maintenance approach will be
followed. Every July, the Steering Committee leader will email the Steering Committee and ask
each member to review the plan and submit any updates or changes that may need to be made
to the plan based on changes to the Hazard Profile, Tribal assets, or the Action Plan. The
Steering Committee leader will collect all correspondence and determine if changes need to be
made to the plan immediately or should be made prior to the plan update in 2014.
During the third year of adoption, the Steering Committee will undertake the following
activities to evaluate the plan and ensure that the HMP is readopted in a timely manner:
•
Review all annual email correspondence regarding plan maintenance.
•
Thoroughly analyze and update the Risk Assessment.
•
Prepare a new Action Plan with prioritized actions, responsible parties, and resources.
•
Prepare a new draft HMP and submit it to the Tribal General Council for adoption.
•
Submit an updated HMP to the FEMA for approval.
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Obtaining Continued Public Involvement
The Steering Committee is dedicated to involving the public directly in the continual reshaping
and updating of the HMP. A copy of the plan will be available at the Tribe’s Main Office.
The Steering Committee will also identify opportunities to raise community awareness about
the HMP and the hazards that affect the Tribe. This effort could include attendance and
provision of materials at Tribal emergency preparedness and response special events.
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Chapter 3
This section describes the history, location, and geography of the Tribe and the Reservation as
well as its government, demographic information, and current land use and development
trends.
History and Description of the Reservation
The Nez Perce Indians, who call
themselves NiMiiPuu, have resided
in what is now north-central Idaho,
southeastern Washington, and
northeastern Oregon for thousands
of years. Until the mid-1800s, the
tribe’s aboriginal territory included
over 13 million acres. The territory
centered on the middle Snake and
Clearwater Rivers and the northern
Salmon River.
In 1855 the Nez Perce Indians
signed a treaty with the U.S.
Government reserving 7.5 million
acres of land for the Nez Perce
Reservation. However, the discovery
of gold by the early 1860s prompted
the U.S. Government to reduce the
Reservation by almost 90 percent, to
its current size of 770,000 acres2
(Figure 1).
Figure 1) Historical and current day boundaries of the Nez Perce
Reservation.
By 1877, with continued pressure to sell off the Nez Perce lands, the U.S. Government tried to
persuade a band of Nez Perce Indians to leave Oregon and move to the Reservation. While the
tribal chiefs began to make preparations to comply, a handful of young warriors attacked some
white ranchers in revenge for the rancher killing a warrior’s father, thus beginning the 3-month
Nez Perce War.
2
"Gold and the Nez Perce." Native American Netroots, 19 Apr. 2011, nativeamericannetroots.net/diary/929. Accessed 14 Sept.
2018
13
Figure 2) Map of towns and communities on the Nez Perce Reservation and Native American population by County per the
2010 Census.
The Nez Perce first fled to Montana and then to Idaho before heading north toward Canada. On
September 30, about 40 miles from the Canadian border, a bitter battle ensued and 5 days
later, Chief Joseph surrendered with over 400 other tribal members. During the surrender, the
U.S. Government promised to return the Nez Perce Indians to the Reservation, but instead,
they were sent to Oklahoma. Most of the Nez Perce War survivors returned to the Northwest in
14
1885. Ten years later, the Dawes Severalty Act opened the Reservation to non-Indians. As a
result, by 1975, less than 80,000 acres of “checkerboard” land remained under Nez Perce and
individual tribal member ownership. Since 1980, a land acquisition program has resulted in an
increase of Nez Perce ownership to approximately 100,000 acres, with an additional 40,000
acres held by individual tribal members.
Figure 3) Different land use areas on the Nez Perce Reservation.
15
The 1,195.10 square miles of land and 9.22 square miles of water in the current Nez Perce
Reservation are located in Nez Perce, Lewis, Latah, Clearwater, and Idaho counties.
Communities and towns within the Nez Perce Reservation include Myrtle, Lenore, Ahsahka,
Orofino, Spalding, Lapwai, Gifford, Sweetwater, Culdesac, Greer, Reubens, Winchester,
Craigmont, Nezperce, Kamiah, Ferdinand, Greencreek, Kooskia, Stites, Peck, Cottonwood Creek,
Jacques Spur, Slickpoo Mission, Mohler, and Clear Creek. Figure 2 shows the locations of towns
and communities and population by county. Cottonwood, Waha, and Westlake are located off
of the reservation but they are close to the boundary.
Government
The Tribe is governed by the Nez Perce Constitution and By-laws established in 1948 and
revised in 1961. The constitution established the Nez Perce Tribal Executive Committee (NPTEC)
and a council of all adult tribal members, known as the Tribal General Council. The Executive
Committee, consisting of nine members, has the authority to represent the Tribe in
negotiations, promote and protect the health, education, and general welfare of Tribal
members, administer unrestricted Tribal funds, and set rules governing Executive Committee
nominations and elections.
Demographics
Historically, the Tribe had a population around 6,000, which fell to roughly 1,800 by the 1900s.
The decrease in population was due to epidemics from and conflicts with white settlers. Today,
the Tribe’s population is 4,082. This includes 1,372 children (up to 19 years old) and 543 elders
(55 years and older).
With focuses on natural resources, the Tribe’s economic base has traditionally centered around
fisheries and forestry. With the construction of the It’se-Ye-Ye and the Clearwater River Casinos
the Tribe has diversified its economic base significantly.
Land Use and Development Trends
The Nez Perce Tribe Land Enterprise Subcommittee is responsible for the generation of revenue
through land leasing for the benefit of the Nez Perce Tribe as well as the acquisition of land
both on and near the Nez Perce Reservation. Over the past 23 years the Tribe has acquired over
62,300 acres of land on and off the Nez Perce Reservation for economic development, timber
management, and wildlife management (Figure 3). In 2004-2006, as part of the Nez Perce Snake
River Basin Agreement on water rights, approximately 11,297 acres of scattered tracts of public
domain (i.e. Trust lands) were identified for transfer to the Nez Perce Tribe. The total acreage
of land administered by the Land Enterprise is 110,000 acres with 55,000 acres in Tribal Trust
16
(i.e. no Individual Trust in this total) and 12,000 acres of fee land on the reservation and 39,000
acres of fee land off the reservation. Figure 4 shows land by ownership on the reservation.
Figure 4) Land ownership on the Nez Perce Reservation.
17
Chapter 4
Risk Assessment Overview
The requirement of 44 CFR 201.7(c)(2) for conducting a risk assessment is listed below.
Understanding the risk to the Tribe requires the identification of each natural hazard that
occurs within the jurisdictional boundaries of the Reservation. Profiling each hazard’s spatial
extent, frequency, likelihood of future occurrence, and duration will help emergency
management better understand the potential impacts associated with natural hazards.
Recognizing the Tribe’s level of exposure to a hazard provides a measure of risk and
vulnerability from a given hazard to specific locations within the Reservation (Figure 5).
(c)(2) A risk assessment that provides the factual basis for activities proposed in the strategy to
reduce losses from identified hazards. Tribal risk assessments must provide sufficient
information to enable the Indian tribal government to identify and prioritize appropriate
mitigation actions to reduce losses from identified hazards. The risk assessment shall include:
i.
A description of the type, location, and extent of all-natural hazards that can affect the
tribal planning area. The plan shall include information on previous occurrences of
hazard events and on the probability of future hazard events.
ii.
A description of the Indian tribal government vulnerability to the hazards described
in paragraph (c)(2)(i) of this section. This description shall include an overall summary of
each hazard and its impact on the tribe. The plan should describe vulnerability in terms
of:
A. The types and numbers of existing and future buildings, infrastructure, and
critical facilities located in the identified hazard areas;
B. An estimate of the potential dollar losses to vulnerable structures identified
in paragraph (c)(2)(ii)(A) of this section and a description of the methodology
used to prepare the estimate;
C. A general description of land uses and development trends within the tribal
planning area so that mitigation options can be considered in future land use
decisions; and
D. Cultural and sacred sites that are significant, even if they cannot be valued in
monetary terms.
18
Figure 5) Components of risk per the USGS-Oregon Partnership for Disaster Resilience Research Collaboration, 2006.
19
Flood Hazard Profile
Hazard Description and History
Floods can be divided into two major categories on the Reservation: river and flash flood. River
flooding is associated with a river’s watershed, which is the natural drainage basin that conveys
water runoff from rain and snowmelt. River flooding occurs when the flow of runoff is greater
than the carrying capacities of the natural drainage systems. Rain water and snowmelt runoff
that is not absorbed by soil or vegetation seeks surface drainage paths following natural
topography lines. These lines merge to form a hierarchical system of rills, creeks, streams, and
rivers. Generally, floods can be slow or fast rising depending on the size of the river or stream.
Flash floods are much more dangerous and flow much faster than river floods. Flash floods are
caused by the introduction of a large amount of water into a limited geographic extent (e.g.
extreme precipitation events in watersheds less than 50 square miles). They also tend to peak
quickly (e.g. eight hours or less) and more commonly occur in hilly or otherwise confined
terrain. Flash floods occur in both urban and rural settings, principally along smaller rivers and
drainage ways that do not typically carry large amounts of water. This type of flood poses more
significant safety risks than river floods because of the rapid onset, the high-water velocity, the
potential for channel scour, and the debris load.3
River Floods
The most commonly reported flood magnitude measure is the “base flood.” This is the
magnitude of a flood having a one-percent chance of being equaled or exceeded in any given
year. Although unlikely, “base floods” can occur in any year, even successive ones. This
magnitude is also referred to as the “100-year Flood” or “Regulatory Flood”. Floods are usually
described in terms of their statistical frequency. A "100-year flood" or "100-year floodplain"
describes an event or an area subject to a 1% probability of a certain size flood occurring in any
given year. This concept does not mean such a flood will occur only once in one hundred years.
Whether or not it occurs in a given year has no bearing on the fact that there is still a 1% chance
of a similar occurrence in the following year. Since floodplains can be mapped, the boundary of
the 100-year flood is commonly used in floodplain mitigation programs to identify areas where
the risk of flooding is significant. Any other statistical frequency of a flood event may be chosen
depending on the degree of risk that is selected for evaluation, e.g., 5-year, 20-year, 50-year,
500-year floodplain.
3
Statewide Regional Evacuation Study Program. Central Florida Region Technical Data Report. Volume 1-7,
Chapter II – Regional Hazards Analysis. Available online at
http://www.cfrpc.org/EVACUATION%20MASTER%20DVD%20%20PDF%20VERSION/VOLUME%201/Chapter%202/CFRPC%20Chapter%20II%20-%20Hazards%20Analysis.pdf.
20
The areas adjacent to the channel that normally carry water are referred to as the floodplain.
In practical terms, the floodplain is the area that is inundated by flood waters. In regulatory
terms, the floodplain is the area that is under the control of floodplain regulations and
programs (such as the National Flood Insurance Program which publishes the FIRM maps). The
floodplain is often defined as:
“That land that has been or may be covered by floodwaters, or is surrounded by
floodwater and inaccessible, during the occurrence of the regulatory flood.” 4
The nature and extent of a flood event is the result of the hydrologic response of the landscape.
Factors that affect this hydrologic response include soil texture and permeability, land cover
and vegetation, land use and land management practices. Precipitation and snow melt, known
collectively as runoff, follow one of three paths, or a combination of these paths, from the point
of origin to a stream or depression: overland flow, shallow subsurface flow, or deep subsurface
(“ground water”) flow. Each of these paths delivers water in differing quantities and rates. The
character of the landscape will influence the relative allocation of the runoff and will,
accordingly, affect the hydrologic response. Unlike precipitation and ice formation, steps can be
taken to mitigate flooding through manipulation or maintenance of the floodplain. Insufficient
natural water storage capacity and changes to the landscape can be offset through water
storage and conveyance systems that run the gamut from highly engineered structures to
constructed wetlands. Careful planning of land use can build on the natural strengths of the
hydrologic response. Re-vegetation of burned slopes diverts overland flow (fast and flood
producing) to subsurface flow (slower and flood moderating). The failure to recognize or
acknowledge the extent of the natural hydrologic forces in an area has led to development and
occupation of areas that can clearly be expected to flood on a regular basis. Despite this,
communities are often surprised when the stream leaves its channel to occupy its floodplain. A
past reliance on structural means to control floodwaters and “reclaim” portions of the
floodplain has also contributed to inappropriate development and continued flood-related
damages.
Winter weather conditions are the main driving force in determining where and when floods
will occur. The type of precipitation that a winter storm produces is dependent on the vertical
temperature profile of the atmosphere over a given area.5 Unusually heavy snow packs and/or
unusual spring temperature regimes (e.g. rapid warming) may result in the generation of runoff
volumes significantly greater than can be conveyed by the confines of the stream and river
4
FEMA. Federal Emergency Management Agency. National Flood Insurance Program. Washington D.C. Available
online at www.fema.gov.
5
“Snowstorms”. Rampo College. Resource Section for Meteorology. Available online at
http://mset.rst2.edu/portfolios/k/khanna_n/meteorology/snowstorms.htm. October 2006.
21
channels. Such floods are often the ones that lead to widespread damage and disasters. Floods
caused by rapid spring snow melt tend to last for a period of several days to several weeks,
longer than the floods caused by other meteorological events.
On small drainages, the most severe floods are usually a result of rainfall on frozen ground;
however, moderate quantities of warm rainfall on a snow pack, especially for one or more days,
can also result in rapid runoff and flooding in streams and small rivers. Although
meteorological conditions favorable for short-duration warm rainfall are common, conditions
for long-duration warm rainfall are relatively rare. Occasionally, however, the polar front
becomes situated along a line from Hawaii through Oregon, and warm, moist, unstable air
moves into the region.
The major source of flood waters on the Reservation is normal spring snow melt. As spring
melt is a “natural” condition; the stream channel is defined by the features established during
the average spring high flow (bank-full width). Small flow peaks exceeding this level and the
stream’s occupation of the floodplain are common events. The magnitude of most floods on
the Reservation depends on the particular combinations of intensity and duration of rainfall,
pre-existing soil conditions, area of a basin, elevation of the rain or snow level, and the amount
of snow pack. Man-made changes to a basin also can affect the size of floods. Although floods
can happen at any time during the year, there are typical seasonal patterns for flooding based
on a variety of natural processes that cause floods:
•
Heavy rainfall on wet or frozen ground, before a snow pack has accumulated, typically
cause fall and early winter floods
•
Rainfall combined with melting of the low elevation snow pack typically cause winter
and early spring floods
•
Late spring floods result primarily from melting of the snow pack
Flash Flooding
There are three types of flash flooding:
•
Extreme precipitation and runoff events
•
Inadequate urban drainage systems that become overwhelmed by runoff
•
Dam failures
Events that may lead to flash flooding include significant rainfall and/or snowmelt on frozen
ground in the winter and early spring months, high intensity thunderstorms (usually during the
summer months), and rainfall onto burned areas where high heat has caused the soil to
become hydrophobic or water repellent which dramatically increases runoff and flash flood
potential.
22
Flash floods from thunderstorms do not occur as frequently as those from general rain and
snowmelt conditions, but are far more severe. The onset of these flash floods varies from slow
to very quick and is dependent on the intensity and duration of the precipitation and the soil
types, vegetation, topography, and slope of the basin. When intensive rainfall occurs
immediately above developed areas, the flooding may occur in a matter of minutes. Sandy soils
and sparse vegetation, especially recently burned areas, are conducive to flash flooding.
Mountainous areas are especially susceptible to the damaging effects of flash floods, as steep
topography may stall thunderstorms in a limited area and may also funnel runoff into narrow
canyons, intensifying flow. A flash flood can, however, occur on any terrain when extreme
amounts of precipitation accumulate more rapidly than infiltration on any terrain. Flash floods
are most common in Washington during the spring and summer months due to thunderstorm
activity.
Floods that result from rainfall on frozen ground in the winter, or rainfall associated with a
warm, regional frontal system that rapidly melts snow at low and intermediate altitudes (rainon-snow) can be the most severe. Both of these situations quickly introduce large quantities of
water into the stream channel system, easily overloading its capacity.
Occasionally, floating ice or debris can accumulate at a natural or man-made obstruction and
restrict the flow of water. Ice and debris jams can result in two types of flooding:
•
Water held back by the ice jam or debris dam can cause flooding upstream, inundating a
large area and often depositing ice or other debris which remains after the waters have
receded. This inundation may occur well outside of the normal floodplain.
•
High velocity flooding can occur downstream when the jam breaks. These flood waters
can have additional destructive potential due to the ice and debris load that they may
carry.6
Flooding from ice or debris jams is a relatively common phenomenon in central Idaho and can
be a significant contributor to flood-related damages. Small jams frequently occur in many of
the streams throughout the Nez Perce Reservation, particularly at bridge abutments and
culverts.
Dam failures also pose a potential flood hazard. A dam failure is the structural collapse of a dam
that releases the water stored in the reservoir behind the dam. A dam failure is usually the
result of the age of the structure, inadequate spillway capacity, or structural damage caused by
an earthquake or flood. The sudden release of water has the potential to cause human
6
Barnhill, Dave, et al. “Flash Floods – How do they occur?”. Waterlines. Division of Water, Indiana Department of
Natural Resources. Spring-Summer 1999. Indianapolis, Indiana.
23
casualties, economic loss, and environmental damage. This type of disaster is dangerous
because it can occur rapidly, providing little warning and evacuation time for people living
downstream. The flows resulting from dam failure generally are much larger than the capacity
of downstream channels and can, therefore, lead to extensive flooding. Flood damage occurs as
a result of the momentum of the flood caused by the sediment-laden water, flooding over the
channel banks, and impact of debris carried by the flow.
Probability of Future Occurrence
The probability of flood events occurring on Tribal lands is high. Low magnitude flood events
can be expected several times each year. Larger magnitude and high impact flood events have
occurred, but are not likely in any given year. These types of flood events have the highest
probability of occurrence in the winter or early spring and often have a greater impact on the
cities of Laiwai, Kamiah, Kooskia, Stites and other communities/infrastructure located near
natural floodplains. Minor flash flood events are expected annually most likely as a result of
summer thunderstorms or rain-on-snow events.
The South Fork of the Clearwater River runs along the southeastern edge of the Reservation
through Stites and Kooskia before joining with the main stem of the Clearwater River. The
Clearwater River then runs along the eastern edge of the reservation through Kamiah, Greer,
and Orofino. Turning west, the Clearwater River then runs near the northern boundary of the
Reservation and passes through Ahsahka, Lenore, and various other small communities and
outlying residences. The Middle Fork and South Fork of the Clearwater River have a much
higher probability of causing flood damage to area residents and communities. Although the
USGS data is limited for the South Fork, it is clear that the 1964 flood was well outside the
normal range of peak flows for the river. The 1996 and 1997 floods also show up as being
above average peak flows; Table 2 summarizes major flood events on the Reservation. Due to
the density of development as well as the lack of structurally sound levees, the communities of
Kooskia, and Stites as well as several individual residences along the South Fork of the
Clearwater have a high risk to flood events. Lawyer Creek also poses a flooding threat to nearby
communities. In May of 2018 Lawyer Creek flooded Lawyer Canyon which resulted in the
closure of State Highway 162 between Nezperce and Greencreek. Figure 6 shows areas of the
reservation that have been identified as flood hazard areas.
24
Figure 6) Identified flood hazard areas on the Nez Perce Reservation.
Many dikes and levees have been constructed along both the Middle and South Forks of the
Clearwater River in the Kooskia vicinity. A levee on the west bank of the South Fork extends
from the mouth upstream to a point across the river from Third Avenue in Kooskia. The levee
on the east bank begins approximately 1,000 feet downstream of B Street and extends
upstream to approximately 350 feet above First Avenue. The levee begins again at the
25
upstream end of the sewage lagoons,
near Kooskia Airport, and extends
upstream to approximately 5,000 feet
past the southern city limits. South of
the city, there are levees in various places
along both sides of the South Fork
Clearwater River. In February of 1948,
the U.S. Army Corps of Engineers (USACE)
performed clearing and snagging work
along the South Fork levee for 2,000 feet
in anticipation of the spring runoff that
year.
In 1949, the USACE made
emergency repairs to 3,000 feet of the
same levee above River Mile 1.0. These
repairs were required due to the flood of
1948 (Figure 7).
Figure 7) The 1948 flood in Kooskia, ID.
Table 2) History of FEMA-declared floods on the reservation and in surrounding areas.
Year
Disaster
Location
Description
1964
Flood
Idaho, Clearwater, Lewis, and Nez Perce
Counties
Heavy rains and flooding
1974
Flood
Clearwater County
Severe storms, snowmelt, and
flooding
1996
Severe
Storm
Idaho, Clearwater, Lewis, and Nez Perce
Counties
Severe storms and flooding
1997
Severe
Storm
Idaho, Clearwater, and Nez Perce Counties
Severe storms, flooding, mud and
landslides
2005
Flood
Nez Perce County and Reservation
Heavy rains and flooding
2010
Severe
Storm
Idaho and Lewis Counties
Severe storms and flooding
2011
Flood
Nez Perce Reservation Idaho, Clearwater,
and Nez Perce Counties
Flooding, landslides, and
mudslides
2017
Flood
Idaho and Clearwater Counties
Severe storms, flooding,
landslides, and mudslides
After the 1964 flood, local crews constructed a dike along the south side of the Middle Fork.
This dike extends from the intersection of Dike Street in Kooskia and U.S. Highway 12,
downstream 2,000 feet to a point upstream of the sewage lagoons. The dike along the Middle
Fork has been tested twice with large flows in 1972 and 1974. Although flows in these years
26
were not as large as the 1964 flood, they were close, coming within 2,000 cfs. Table 2 displays
FEMA declarations of disaster for flood events on the reservation and in surrounding counties.
The city of Kooskia has a very high risk of flooding from both the Middle and South Forks of the
Clearwater River. The levees currently built along the river banks will likely protect the city
from most flood events; however, most of these levees were built over 50 years ago, need
maintenance, and may not hold during a large event. There are three major dams are located
in the vicinity of the Nez Perce Reservation: Dworshak Dam, Winchester Dam, and Soldiers
Meadow Dam. None of these structures has failed or been subject to significant damage.
However, a threat of potential dam failure occurred for Winchester Dam following a severe
flood/winter storm event in February 1996.
Impacts of Flood Events
Due to several swift bodies of water on the Reservation, the probability of a flood-related
fatality is moderate. Flash flood events in particular, or accidents, could result in a death or
injury. First responders or other persons could be pinned under debris and drowned or receive
trauma from debris being carried along the waterway. Once flood waters recede, mold can
grow in wet material causing a public health hazard. Flood waters may contain sewage and
hazardous chemicals that could be left on people’s property following a flood event.
Furthermore, water and food may be contaminated and heat and electricity may be inoperable
for a period of time. Although the probability of these types of impacts occurring at a
moderate to large scale is very low, all of these factors could contribute to a decline in current
and long-term health of Tribal residents.
The continuity of operations for the Tribe is rarely compromised due to a flood event. The
delivery of some services may be hindered by localized flooding in certain areas; however, due
to the availability of alternative routes, this is not a significant concern. Damage to facilities,
equipment, or files could impact certain organizations or public services depending on the
extent of damage and duration of the event.
Flood events on the Reservation are most likely to affect private property by damaging homes,
businesses, barns, equipment, livestock, and vehicles. Both water and contaminants can
damage or permanently ruin equipment. Flood waters can also erode land. This is particularly
an issue when lands supporting roads, power lines, pipelines, sewage control facilities, levees,
bridges, and other infrastructure are damaged by erosion. Some environmental impacts that
may be realized by localized flooding could include erosion of stream banks, loss of riparian
plant life, or contamination by chemicals or sewage. Flooding in some areas may have some
environmental benefits such as establishing meanders that slow the stream flow, replenishing
wetland areas, and replenishing the soil with nutrients from sediment.
27
Flooding on the Reservation is likely to have a significant or long-term effect on the local
economy. Depending on the magnitude of the event, individual residents and businesses may
be adversely impacted, but the economic viability of the community will not be affected.
Severe damage to transportation infrastructure may have a short-term impact on certain
communities due to the presence of state and U.S. highway routes, but alternative routes are
available.
Changes in the timing and intensity of precipitation is an expected result of a changing climate,
the Idaho State Hazard Mitigation Plan (SHMP) states that areas within the United States that
are prone to flooding will increase by up to 45% by 21007. In addition, by 2050 snowmelt is
projected to occur three or four weeks earlier than the 20 th century average. The Clearwater
Sub-basin is expected to shift from a snow-dominant basin to a rain-snow and rain dominant
basin by mid-century, and heavy downpours are projected to increase by 13% (Hamlet et. Al
2013, U.S. Global Change Research Program8). Heavy downpours in rain-snow mix and rain
dominant basins could increase flood risk, and stormwater management challenges. In
addition, the dry season, and the fire season, is expected to be longer and more intense in the
Pacific Northwest, leading to a greater probability of erosion, mud-slides, and landslides during
precipitation events that could exacerbate the severity of floods (U.S. Global Change Research
Program, 2014, National Climate Assessment).
Development in or near floodplains increases the likelihood of flood damage. New
developments near a floodplain add structures and people in flood areas thereby increasing,
not the extent of the flood itself, but the impacts or damages that may be caused. New
construction can also alter surface water flows by diverting water to new courses or increasing
the amount of water that runs off impervious pavement and roof surfaces. This second effect
diverts waters to places previously unaffected by flood issues. Unlike the weather and the
landscape, this flood-contributing factor can be controlled. Development and occupation of the
floodplain places individuals and property at risk. Such use can also increase the probability
and severity of flood events (and consequent damage) downstream by reducing the water
storage capacity of the floodplain, or by pushing the water further from the channel or in larger
quantities downstream.9
7
FEMA U.S. (2013). The Impact of Climate Change and Population Growth on the NFIP through 2100.
8
Alan F. Hamlet , Marketa McGuire Elsner , Guillaume S. Mauger , Se-Yeun Lee , Ingrid Tohver & Robert A.
Norheim (2013) An Overview of the Columbia Basin Climate Change Scenarios Project: Approach, Methods, and
Summary of Key Results, Atmosphere-Ocean, 51:4, 392-415, DOI: 10.1080/07055900.2013.819555
9
Planning and Flood Risk. Planning Policy Statement 15. The Planning Service, Department of Environment. June
2006. Available online at
http://www.planningni.gov.uk/index/policy/policy_publications/planning_statements/pps15-flood-risk.pdf.
28
Dam Failure
Three major dams are located in the vicinity of the Nez Perce Reservation: Dworshak Dam,
Winchester Dam, and Soldiers Meadow Dam (Figure 8). None of these structures has failed or
been subject to significant damage. However, a threat of potential dam failure occurred for
Winchester Dam following a severe flood/winter storm event in February 1996.
Three of the dams are regulated by the Idaho Department of Water Resources (IDWR). Dams
regulated by the IDWR include concrete and earthen structures that are 10 feet higher or store
more than 50-acre feet of water. The largest dam located within the Reservation is Dworshak
Dam. Dworshak Dam, which is fed by the North Fork Clearwater River, is located in Clearwater
County, 5 miles north of Orofino. As the biggest concrete dam in the State, it is over 633 feet
high and has a storage capacity of 3,453,000 acre-feet.
The second, smaller dam, Soldiers Meadow Dam, is located 6 miles southeast of Waha in Nez
Perce County. This earthen dam, which is fed by Webb Creek, is 50 feet high and has a water
storage capacity of 2,370 acre-feet. The smallest dam located near Winchester in Lewis County
is Winchester Dam. Winchester Dam, which is also an earthen dam, is 36 feet high and can hold
more than 850 acre-feet of water.
The IDWR classifies potential losses and damages anticipated to downstream areas during a
dam failure. Dworshak Dam, Soldiers Meadow Dam, and Winchester Dam are all classified as
high risk. Dams rated in this classification can potentially inundate downstream areas with
floodwater levels with depths of more than 2 feet and/or a velocity of 2 feet or more per
second.
Failure of Dworshak Dam would likely be contained without causing failure of McNary Dam,
near Umatilla, Oregon. However, dam failure would cause property damage to rail lines along
the Clearwater and Snake rivers; Highways 12 and 730; and the Nez Perce Tribal Fish Hatchery
on the Clearwater River and numerous other structures in the flood plain. Flooding would occur
at Orofino within 45 minutes, with a peak flood time of 3 hours and 45 minutes and a peak
water level of 80 feet. Flooding would also affect the Nez Perce National Historical Park within 2
hours, with a peak time of 5 hours and 30 minutes and a peak water level of 55 feet.
Floodwater arrival at the confluence of the Snake and Clearwater rivers in Lewiston would be 3
hours and 15 minutes, with a peak water level of 52 feet at 6 hours and 30 minutes. In addition,
floodwaters would affect the communities of Mrytle, Lenore, Spalding, and Ahsahka.
Floodwaters would not directly impact the city of Lapwai.
Failure of Soldiers Meadow Dam would have a significant impact on the city of Lapwai and the
Tribal Headquarters. In a sudden failure, floodwaters would reach the city of Lapwai within an
hour and affect the entire valley floor at Sweetwater, Lapwai, and Spalding. The depth and
duration of the flood is also dependant upon conditions.
29
Figure 8) Dam location and areas likely to be inundated in the event of a dam failure on the Nez Perce Reservation.
30
In a sudden failure, floodwaters from Winchester Dam could reach the city of Lapwai fairly
soon. Floodwaters would impact Culdesac, Sweetwater, Lapwai, and Spalding. The depth and
duration of the flood is dependant upon conditions and are not absolutely certain. It has been
determined that a series of culverts leading this stream through Highway 95 would slow the
progress of floodwaters significantly and buffer the impact of dam failure.
All three dams are inspected annually by the IDWR to ensure that they are in good operating
condition. An imminent dam failure for any of the three dams is not expected due to structural
damage caused by earthquakes or flooding. In addition, all three dams are considered to be at
low-risk to terrorists’ attacks.
Value of Resources at Risk
Nearly all of Kooskia on both sides of the South Fork of the Clearwater River and a significant
portion of the city along the south side of the Middle Fork, particularly on the eastern edge,
have a high risk of flooding. This includes large sections of residential areas as well as much of
the Main Street business district. City Hall, the fire department, the airport, the wastewater
treatment facility, and three municipal well heads are included in this floodplain. Just south of
the city limits, the floodplain also includes the Clearwater Forest Industries mill and a portion of
the parcel containing Clearwater Valley High School. Furthermore, a section of State Route 13
through downtown Kooskia and a section U.S. Highway 12 on the north side of the Middle Fork
are within the floodplain and could potentially be damaged or closed. The State Route 13
bridge crossing on the Middle Fork and a smaller access bridge about ½ mile upstream are also
in the floodplain; however, both of these bridges were built to withstand a major flood event.
At the time of the development of this plan, an analysis of the value of structures at risk was
not performed due to data limitations. However, Table 3 displays the type and number of
structures found in different flood and inundation zones identified on the reservation (hazard
zone acronyms are defined below the table). Reservation-wide, more than 1,700 structures are
located in tributary flood zones and in the event that the Clearwater River Dam failed, more
than 1,700 structures would be at risk. Refer to the maps in this section and the Vulnerable
Areas and Infrastructure section for total values at risk on the Nez Perce Reservation.
31
Table 3) Type and number of structures located in both tributary flood zones (all areas within 500ft of tributaries)
and Clearwater River dam inundation zones as identified on the Nez Perce Reservation. A count of outbuildings
could not be made but the quantity was estimated to be several hundred.
Structure Type
Homes/Residential
Commercial and Commercial-type
Other School Buildings
Churches
Schools
Historical Structures
Children’s Home
Hospital
Health Clinic
Senior Citizen Facility
Prison
Outbuildings
Total
Count of Structures in Designated Hazard Zones
F.Z.’s
C.R. Dam
L.C. Dam
WC/SWC
1,302
1,462
738
64
385
297
85
4
16
15
21
5
3
2
6
1
1
3
1
1
1
1
1
1
Hundreds
Hundreds
Hundreds
Several
1,713*
1,779*
856*
68*
F.Z.’s –Flood Zones (all areas within 500 feet of tributaries)
C.R. Dam –Clearwater River Dam Inundation Zone
L.C. Dam –Lapwai Creek Dam Inundation Zone
WC/SWC –Webb/Sweetwater Creek Inundation Zone
*Value includes countable structures only (outbuildings were not included).
32
Severe Weather Hazard Profile
Severe weather is a serious hazard that can and does affect the Nez Perce Reservation on a
regular basis. Severe weather affects the entire state of Idaho with varying degrees, due to the
complex landscape and the influence from the Pacific Ocean. Although Idaho’s severe weather
is minimal in comparison with the rest of the nation, severe weather poses a significant hazard
to the state and local communities. Storm-related Presidential Disaster declarations were made
for Idaho in 1964, 1972, 1974, 1996, 1997, 2005, 2006, and 2010; Most of these storms resulted
in flood damages. Severe weather within the Reservation consists of droughts, hailstorms, and
windstorms; Figure 9 is a map of past major storm occurrences in Idaho.
The pattern of average annual
temperatures for the Reservation
indicates the effects of altitude on
temperature. The highest annual
averages are found in the lower
elevations of the Clearwater and
downstream to Lewiston. The range
between the mean temperature of
the coldest and warmest months of
the year varies from less than 40F,
to well over 50 F at stations in the
higher elevation. In summer, periods
of extreme heat extending beyond a
week are quite rare; the same can
be said of periods of extremely low
temperatures in winter. In both
cases the normal progress of
weather systems across the
Reservation usually results in a
change at rather frequent intervals.
Extreme
temperatures,
when
coupled with low precipitation for
extended periods of time, can lead
to a drought.
Figure 9) Past Occurrence of severe storms across Idaho (Idaho Hazard
Mitigation Plan, 2013).
Thunderstorms are a common occurrence across the Reservation and with them comes the
potential for a variety of other severe weather phenomenon. Due to their relative frequency
and minimal severity, severe thunderstorms are not well documented across the Reservation.
33
Typically, their impacts are fairly limited and do not significantly affect the communities. The
secondary effects of thunderstorms can be widespread and include hail, high winds, and
lightning events.
Past weather patterns show that severe weather conditions are likely to happen in any part of
the Nez Perce Reservation in any given year. The topographical features of the area contribute
greatly to the various weather patterns that occur. All areas within this region are vulnerable to
severe local storms.
Drought
Drought is an expected phase in
the climactic cycle of almost any
geographical region. Objective,
quantitative
definitions
for
drought
exist
but
most
authorities agree that, because
of the many factors contributing
to it and because its onset and
relief are slow and indistinct,
none are entirely satisfactory.
According to the National
Drought
Mitigation
Center,
drought originates from a
deficiency of precipitation over
an extended period of time,
usually a season or more. This
deficiency results in a water Figure 10) Types of drought (National Drought Mitigation Center).
shortage for some activity,
group, or environmental sector. What is clear is that a condition perceived as “drought” in a
given location is the result of a significant decrease in water supply relative to what is “normal”
in that area.10
It should be noted that water supply is not only controlled by precipitation (amount, frequency,
and intensity), but also by other factors including evaporation (which is increased by higher
than normal heat and winds), transpiration, and human use (Figure 10). Drought in Idaho is
generally associated with a sustained period of low winter snowfall. This results from a
10
National Oceanic & Atmospheric Administration. 2010. U.S. Drought Monitor. Drought Information Center. U.S.
Department of Agriculture. Available online at http://www.drought.noaa.gov/index.html.
34
temporary, yet significant, change in the large-scale weather patterns in the western U.S. The
limited snow packs result in reduced stream flows and ground water recharge. Idaho’s system
of reservoirs and natural storage can buffer the effects of minor events over a few years, but a
series of dry winters (or an especially pronounced single low snowfall event) will result in a
shortage of available water. Extended periods of above-average temperatures during the
spring and summer can increase the impacts of low snow packs. Flash droughts are another
type of drought that are associated with climate change, and are produced from increased
temperatures and/or reduced precipitation resulting in rapidly decreasing soil moisture.
In every drought, agriculture is adversely impacted, especially in non-irrigated areas such as the
dry land farms and rangelands in and throughout the Nez Perce Reservation. Droughts impact
individuals (farm owners, tenants, and farm laborers), the agricultural industry, and other
agriculture-related sectors. The severity of drought is measured by the Palmer Index in a range
of 4 (extremely wet) to -4 (extremely dry). The Palmer Index incorporates temperature,
precipitation, evaporation and transpiration, runoff and soil moisture when designating the
degree of drought.11
Probability of Future Occurrence
The Idaho Department of Water Resources reports that meteorological drought conditions (a
period of low precipitation) existed in the State approximately 30% of the time during the
period 1931-1982. Principal drought in Idaho, indicated by stream flow records, occurred during
1929-41, 1944-45, 1959-61, 1977, and 1987-92.12 According to the State of Idaho, a drought
from 1987-1992 resulted in the worst water shortage in 10 years. Additionally, below-capacity
reservoirs resulted in reduced irrigation capacity, plowed-under crops, high water
temperatures, and starvation of wildlife due to the lack of perennial grass growth. The Nez
Perce Reservation, along with much of Idaho, experienced another seven year drought from
1999 to 2005. While 2006 and 2008 were not drought years, 2007 had severe drought most of
the year with extreme drought from August to October.
The historical records demonstrate a cyclical pattern that shows drought is likely to occur on
the Reservation about every 10 years and last from 1 to 7 years with varying degrees of severity
(Figure 11). The effects of droughts will be compounded by the influences of a climate change;
altered weather and precipitation patterns, and increased average annual temperatures could
lead to prolonged periods of drought.
11
“Drought Monitoring”. National Weather Service Climate Prediction Center. NOAA. February 2011. Available
online at http://www.cpc.ncep.noaa.gov/products/monitoring_and_data/drought.shtml.
12
Idaho Department of Water Resources. 2010. Idaho Drought Emergency Declarations. Available online at
http://www.idwr.idaho.gov/News/drought/drought.htm.
35
Figure 11) Palmer Drought Severity Index for the Nez Perce Reservation in 2017.
Impacts of Drought Events
Drought affects water levels for use by industry, agriculture, and individual consumers. Water
shortages affect firefighting capabilities through reduced flow and pressure. Drought also
affects power production. Much of Idaho’s power is produced by hydro-electric dams. When
water levels drop, electric companies cannot produce enough power to meet demand and are
forced to buy electricity from other sources. Oftentimes, drought is accompanied by extreme
heat. When temperatures reach 90 degrees and above, people are vulnerable to sunstroke,
heat cramps, and heat exhaustion. Pets and livestock are also vulnerable to heat-related
injuries. Crops can be vulnerable as well. In the past, droughts within the Reservation resulted
in significantly lessened crop yields. Drought increases the danger of wildland fires. Fires in
rangeland areas are particularly dangerous due to typically high rates of spread and the
scattered nature of structures and infrastructure.
Compounding the effects of droughts are the impacts from a changing climate. Following the
assessment of the Idaho State Hazard Mitigation Plan that recognized the potential to
experience more frequent and severe droughts to communities in Idaho, the Tribe recognizes
the need to protect water and food resources.
36
Value of Resources at Risk
Although the financial impacts of drought can be substantial and extended, accurately
quantifying these impacts is problematic. Drought typically does not cause direct losses to
structures or infrastructure, although the forest and rangelands throughout the Reservation are
at increased risk to wildfires as a result of drought conditions. Reservation lands have
experienced numerous large wildland fires in the past two decades resulting in thousands of
acres of forest and rangeland burned and numerous structures and livelihoods lost. The
resulting smoke and road closures often affect local citizens as well have impacts on the
economy.
Due to the nature of the hazard, it is difficult to quantify potential loses as a result of drought.
However, the tangible losses are most clearly seen in the agriculture and livestock ranching
sectors of the Reservation’s economy. Dry land agriculture can be negatively impacted by
drought conditions due to reduced yields and limited crop diversification. Livestock ranchers
may be forced to recalculate range carrying capacities, change field rotations, and provide
supplemental feed for livestock. Reduced hydroelectric power production can also result from
decreased water levels in the area reservoirs.
Hailstorms
Hail can occur in any strong thunderstorm, which means hail is a threat throughout the
Reservation. Hail is precipitation that is formed when updrafts in thunderstorms carry
raindrops upward into extremely cold areas of the atmosphere. Formation of larger hail stones
can fall at speeds faster than 100 miles per hour. Often the hail that occurs does not grow to a
size larger than one-half inch in diameter and the areas affected are usually small. Quite often
hail comes during early spring storms, when it is mostly of the small, soft variety with a limited
damaging effect.
Probability of Future Occurrence
In July of 1995 several severe thunderstorms moved through the state of Idaho. One
thunderstorm in Northern Idaho produced hail .75 inch to 1.50 inches in diameter and high
winds that downed power lines and trees in Nez Perce, Lewis, Latah, Shoshone, and Idaho
Counties. One-inch hail fell near Cottonwood and 1.50 inches hail fell near Grangeville. This
storm damaged the wheat and barley crops at a 100 percent loss in the Cottonwood area. Just
south of Cottonwood, trees were uprooted and the roof of an apartment building was torn off
causing extensive property damage. This area also suffered a power outage. Winds at Fenn and
Cottonwood shattered windows and hail dented automobiles. Large hailstones, 2-3 inches in
diameter, were observed throughout some areas of the Pacific Northwest in early spring of
37
1997. Thunderstorms in spring of 2006 and 2007 produced hailstones that were reported at
1.75” in diameter near Culdesac and Lenore.
These types of damaging hailstorms are typically infrequent and localized to a fairly small area.
Based on previous occurrences, the likelihood of a hailstorm event within the Reservation
occurring is every 5 years. The more common hailstorms that often accompany thunderstorms
generally occur several times each year, but cause limited to no damage.
Impacts of Hailstorms
The effects are generally transportation accidents and loss of utilities. When transportation
accidents occur, motorists are stranded and schools and businesses close. The effects vary with
the intensity of the storm, the level of preparation by local jurisdictions and residents, and the
equipment and staff available to perform tasks to lessen the effects of severe local storms.
There is no way to prevent severe storms. The weather forces and topography of Nez Perce
Reservation will always dictate when and where severe storms will occur.
The potential impacts of a severe hail storms include crop damage, downed power lines,
downed or damaged trees, broken windows, roof damage, and vehicle damage. Hail storms
can, in extreme cases, cause death by exposure. The most common direct impact from ice
storms to people is traffic accidents. Over 85% of ice storm deaths nationwide are caused by
traffic accidents. Hail storms also have the potential to cause losses among livestock. The
highest potential damage from hail storms is the economic loss from crop damage. Even small
hail can cause significant damage to young and tender plants.
Value of Resources at Risk
Although the financial impacts of hail can be substantial and extended, accurately quantifying
these impacts is problematic. Hail typically causes direct losses to structures and other
personal property as well as to the extensive agricultural development. Potential losses to
agriculture can be disastrous. They can also occur locally; thus, individual farmers can have
significant losses, but the event may not drastically affect the economy of the Reservation.
Furthermore, crop damage from hail will also be different depending on the time of year and
the type of crop. Most farmers carry insurance on their crops to help mitigate the potential
financial loss resulting from a localized hail storm. Federal and state aid is available with
declared hail disasters resulting in significant loss to local farmers as well as the regional
economy. Homeowners rarely incur severe damage to structures (roofs); however, hail damage
to vehicles is not uncommon. The damage to vehicles is difficult to estimate because the
number of vehicles impacted by a specific ice storm is unknown. Additionally, most hail damage
records are kept by various insurance agencies.
38
Windstorms
The National Weather Service defines high winds as sustained winds of 40 mph or gusts of 58
mph or greater, expected to last for an hour or more.13 Windstorms are frequent across all of
the Reservation and they have been known to cause substantial damage (Table 4). Under most
conditions, the area’s highest winds come from the northwest. However, during the summer
months lightning and thunderstorms often come from the south to southwest. Due to the
abundance of agricultural development on the Reservation, crop damage due to high winds can
have disastrous effects on the local economy. In the case of extremely high winds, some
buildings may be damaged or destroyed, and tractor-trailers overturned. Wind damages will
generally be categorized into three groups: 1) structure damage to roofs, 2) structure damage
from falling trees, and 3) damage from wind-blown dust on sensitive receptors. Structural injury
from damaged roofs is not uncommon. Airborne particulate matter increases during high wind
events, especially under drier conditions, which can lead to reduced visibility and increased
transportation related accidents. When wind blowing dust events occur, sensitive receptors
including the elderly, children, and those with asthma are at increased risk of breathing
complications.
Table 4) Records of wind gust at the Lewiston Airport, historical maximum recorded wind gust for each month by year
recorded.
Year
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
Historic
Max
Year
44
43
43
49
47
47
43
36
41
46
40
38
28
33
43
38
59
31
28
43
56
37
52
55
52
40
37
39
45
41
51
48
52
36
52
32
41
41
39
36
51
43
45
47
37
31
26
52
39
36
41
51
47
37
47
46
33
37
38
44
52
33
46
44
39
39
36
40
49
35
33
40
48
41
43
47
41
39
43
37
39
52
49
52
47
85
32
60
33
39
28
35
41
38
41
39
44
40
37
56
37
24
53
43
46
49
39
36
51
43
44
36
41
48
48
44
37
63
52
36
38
35
41
32
48
40
59
38
47
48
47
48
60
59
55
54
52
52
63
85
47
58
63
59
2000
2008
2004
2002
2006
2001
1998 2011
2000
2001
2010
2008
Microbursts are columns of cold sinking air within a thunderstorm and is typically less than 2.5
miles across and can reach speeds of up to 100 mph. Microburst progress through a series of
stages; contact stage is when the descending air makes contact with the surface and the
13
http://www.nhc.noaa.gov/aboutgloss.shtml#h. Accessed October, 2012.
39
highest windspeeds are observed, outburst stage occurs as the air moves outward from the
point of contact, and cushion stage is the final stage where winds along the surface begin to
slow due to increased friction. Wind speeds from microbursts can cause significant damage and
are potentially life threating.
A tornado is formed by the turbulent mixing of layers of air with contrasting temperature,
moisture, density, and wind flow. This mixing accounts for most of the tornadoes occurring in
April and May, when cold, dry air from the north or northwest meets warm, moister air moving
up from the south. If this scenario was to occur and a major tornado was to strike a populated
area within the Reservation, damage could be widespread. Businesses could be forced to close
for an extended period, and routine services such as telephone or power could be disrupted.
The National Weather Service defines a tornado as a violently rotating column of air that
contacts the ground; tornados usually develop from severe thunderstorms.14 Areas most
vulnerable to tornados are those subject to severe thunderstorms or those with a recurrence
rate of 5 percent or greater, meaning the Reservation experiences one damaging severe
thunderstorm event at least once every 20 years (Table 5).
Table 5) List of tornadoes that have touched down in and around the Nez Perce Reservation.
ID
Date
Time
Dead
Inj.
F-Scale
Beg. Coord
End Coord.
County
150
11-Apr-79
14:00
0
0
0
45.92, -116.13
0.00, 0
Idaho
1099
7-Oct-10
17:20
0
0
0
46.13, -116.42
46.13, -116.42
Idaho
1100
7-Oct-10
17:41
0
0
0
46.19, -116.36
46.19, -116.37
Lewis
124
8-May-62
16:00
0
0
2
46.40, -116.80
46.40, -116.60
Nez Perce
280
20-Jun-69
16:35
0
0
1
46.50, -116.80
0.00, 0
Nez Perce
707
31-May-97
15:10
0
0
0
46.42, -116.97
46.42, -116.97
Nez Perce
Probability of Future Occurrence
On May 31, 1997, six tornadoes touched down in Washington and Idaho in one day. In nearby
Lewiston, an F0 tornado along with 70 mph+ winds was observed. In 1999, an intensified
thunderstorm produced wind gusts over 50 mph on the Nez Perce Reservation. In December
2006 winter storms produced windstorms of 76 kts (F1 is 73 kts) in Lewis County and several
14
http://www.noaawatch.gov/themes/severe.php. Accessed October, 2012
40
occurrences over 50 kts were reported across the reservation. In May 2008 a funnel cloud was
spotted near Grangeville.
Throughout the Nez Perce Reservation, the strongest windstorms are generally associated with
rapidly moving weather systems that occur between October and March. Generally these south
and southwesterly winds can remain at 20–30 mph for several hours and reach peak speeds of
more than 50 mph. In the summertime, windstorms are often associated with thunderstorm
activity. Based on previous occurrences, the likelihood of a significant windstorm (wind speeds
of in excess of 50 mph) occurring on the Reservation is every 4 years.
Impacts of Windstorms
The impacts of an extreme wind event to the community are usually minimal; however, the
area affected by extreme wind events can be widespread making response difficult. Utilities
and transportation are usually impacted by extreme wind events, either by poor road
conditions to downed trees that block roadways and disrupt power distribution. Damage to
structures, largely the loss of roofing materials, does occur on a more localized scale and is
influenced by building materials and age of structure. Depending on the season of the event,
severe winds may result in a loss of agricultural crops.
Value of Resources at Risk
It is difficult to estimate potential losses to the Reservation due to windstorms and tornadoes.
Construction has been implemented in the presence of high wind events, and therefore, the
community has a higher level of preparedness to high wind events than many other areas
experiencing lower average wind speeds. Refer to the Vulnerable Areas and Infrastructure for
more information about total values at risk on the reservation.
Winter Storms
Summer water supplies are dependent on winter storms brining snow packs to the mountains
that surround the Reservation. While winter snow is a necessary component of life on the
Reservation it also brings with it many potential disasters. Winter weather can impact
transportation, disrupt utility services, cutoff remote residents from services, and reduce
emergency services effectiveness.
Winter storms are a part of life on the Reservation. Storms vary in degree and intensity and can
occur at any time but are especially probable between September and April. These storms
could be localized or could affect the entire state. They can last a matter of minutes or over
many days. Typically, winter storms are measured by the amounts of snow accumulated during
any given storm. Additionally, these storms could be measured by the accompanied wind or
temperatures associated with each storm.
41
In any discussion about winter storms, terminology and the general characteristics of the
causes and impacts of winter storms need to be defined. Natural winter storm events are
grouped into the following categories:
•
Showers – Snow falling at varying intensities for brief periods of time. Some
accumulation is possible.
•
Squalls – Brief, intense snow showers accompanied by strong, gusty winds.
Accumulation may be significant. Snow squalls are best known in the Great Lakes
Region.
•
Blowing Snow – Wind-driven snow that reduces visibility and causes significant drifting.
Blowing snow may be snow that is falling and/or loose snow on the ground picked up by
the wind.
•
Blizzard – A winter storm with winds over 35 mph and temperatures of 20 degrees F.,
Accompanied by blowing snow that reduces visibility to near zero.
•
Sleet – Rain drops that freeze into ice pellets before reaching the ground. Sleet usually
bounces when hitting a surface and does not stick to objects. However, it can
accumulate like snow and cause a hazard to motorists.
•
Freezing Rain – Rain that falls onto a surface with a temperature below freezing. This
causes it to freeze to surfaces, such as trees, cars, and roads, forming a coat or glaze of
ice. Even small accumulations of ice can cause a significant hazard.
•
Severe Winter Storm - defined as one that drops four or more inches of snow during a
twelve-hour period, or six or more inches during a twenty-four-hour period.
•
Ice storm - occurs when cold rain freezes immediately on contact with the ground,
structures, and vegetation.
Snow plowing on the Reservation occurs from a variety of departments and agencies. The state
highways are maintained by the State of Idaho. Plowing of county roads is done by the local
highway districts and county road departments. Cities and towns are maintained by their
respective road maintenance program and BIA/Tribal roads are maintained by the Tribal Road
Maintenance Program. Roads that are not public access, such as roads on private property, are
the responsibility of the landowner.
Probability of Future Occurrence
Historical accounts of past severe winter weather demonstrate the likelihood of future
occurrence. The following is a non-comprehensive list of events that occurred within or around
the Reservation.
42
Severe Storms, Flooding, Landslides, and Mudslides – FEMA-4313-DR (2017)
Much of northern Idaho was declared a major disaster due to severe storms that caused
flooding, landslides, and mudslides beginning on March 6 and running through March 28 of
2017. Damage was primarily to roadways and bridges. An estimated cost was $9,625,389 and
covered 8 counties in northern Idaho.
Severe Winter Storms – FEMA-2452-DR (2016)
Counties just north of the reservation in Idaho experienced severe winter storms from
December 16-27, 2015. Governor Butch Otter requested a disaster declaration for the three
counties effected (Benewah, Bonner, and Kootenai). The storm resulted in damage to public
utilities with an estimated cost of $5,290,887.
Severe Storms, Flooding, Landslides, and Mudslides – FEMA-1987-DR (2011)
March 31 to April 11, 2011 brought flooding that resulted in landslides and mudslides leading to
damaged roadways and bridges. The estimated cost to the public was $4,602,005, with a per
capita cost for the Tribe at $75.72. Disaster declaration by President Obama allowed for a cost
share of emergency work and repair of damaged infrastructure.
Heavy Rains and Flooding – FEMA-186-DR (1964)
Nicknamed the Christmas Flood of 1964, claiming 47 lives and roughly $4 billion in damage
(today’s cost). Areas affected by the storm included ~200,000 square miles in Idaho,
Washington, Oregon, and California. Intense rainfall, producing as much as 15 inches in 24
hours in some locations, coupled with frozen ground and melting snow produced increased
runoff in streams that were already running high due to snow melt15.
Winter storms occur annually with varying degrees of intensity, but are mostly likely to be
damaging in the higher elevation communities of Winchester, Craigmont, Greencreek,
Nezperce, and Reubens where colder temperatures and limited windbreaks exacerbate the
effects of snow accumulation. More extreme winter weather with long term cold
temperatures, high winds, and/or snow accumulation occurs about every 3-5 years affecting
some or all of the Reservation at one time.
Impacts of Winter Storms
Winter storms damage roofs by heavy snow accumulations with extent of the damage
depending on the moisture content of the snow and the structural characteristics of the
buildings. Blowing snow can cause vehicle and other types of accidents and can contribute to
15
The Christmas Flood of 1964. (2014). USGS. Retrieved from: https://www.usgs.gov/news/christmas-flood-1964
43
livestock losses from exposure. Ice can cause damage to powerlines, trees, and some
structures and is likely to cause vehicle accidents or at least make driving conditions hazardous.
Power outages often occur during winter storms lasting from several hours to days. This has a
two-fold impact on residents as not only is power cut to homes and businesses, but primary
heating is lost for many residents. Gas furnaces and wood stoves supplement electrical
heating, but with wood heating the senior population is at a disadvantage.
Frozen water pipes are the most common damage to residential and business structures. Older
homes tend to be at a higher risk to frozen water pipes than newer ones. More rural parts of
the Reservation are sometimes better prepared to deal with power outages for a few days due
to the frequent occurrence of such events; however, prolonged failure, especially during cold
winter temperatures can have disastrous effects. All communities should be prepared to deal
with power failures. Community shelters equipped with alternative power sources will help
local residents stay warm and prepare food. A community-based system for monitoring and
assisting elderly or disabled residents should also be developed. All households should
maintain survival kits that include warm blankets, flashlights, extra batteries, nonperishable
food items, and clean drinking water.
Emergency response to severe winter storms includes site visits by police or fire department
personnel, opening of shelters, or assistance with shopping, medical attention, and
communications.
Value of Resources at Risk
The economic losses caused by severe winter storms may frequently be greater than structural
damages. Employees may not be able to travel to work for several days and businesses may
not open. Damages are seen in the form of structural repair and loss of economic activity.
Refer to the Vulnerable Areas and Infrastructure for more information about total values at
risk on the reservation.
44
Landslide Hazard Profile
Hazard Description and History
Landslide is a general term for a wide variety of down slope movements of earthen materials
that result in the perceptible downward and outward movement of soil, rock, and vegetation
under the influence of gravity. The materials may move by falling, toppling, sliding, spreading,
or flowing. Some landslides are rapid, occurring in seconds, whereas others may take hours,
weeks, or even longer to develop. Although landslides usually occur on steep slopes, they also
can occur in areas of low relief.16
Landslides range from shallow debris flows to deep-seated slumps. They destroy homes,
businesses and public buildings, undermine bridges, derail railroad cars, interrupt
transportation infrastructure, damage utilities, and take lives. Sinkholes affect roads and
utilities. Losses often go unrecorded because insurance claims are not filed, no report is made
to emergency management, there is no media coverage, or the transportation damages are
recorded as regular maintenance.
Landslides can occur naturally or be triggered by human-related activities. Naturally-occurring
landslides can occur on any terrain, given the right condition of soil, moisture content, and the
slope’s angle. They are caused from an inherent weakness or instability in the rock or soil
combined with one or more triggering events, such as heavy rain, rapid snow melt, flooding,
earthquakes, vibrations, and other natural causes. Other natural triggers include the removal of
lateral support through the erosive power of streams, glaciers, waves, and longshore and tidal
currents; through weathering, wetting, drying, and freeze-thaw cycles in surficial materials; or
through land subsidence or faulting that creates new slopes. Long-term climate change can
influence landslide occurrences through increased precipitation, ground saturation, and a rise
in groundwater level, which reduces the strength and increases the weight of the soil.
Landslides can also be induced, accelerated or retarded by human actions. Human-related
causes of landslides can include grading, slope cutting and filling, quarrying, removal of
retaining walls, lowering of reservoirs, vibrations from explosions, machinery, road and air
traffic, and excessive development. Normally stable slopes can fail if disturbed by development
activities. Often, a slope can also become unstable by earthmoving, landscaping, or vegetation
clearing activities. Changing drainage patterns, groundwater level, or slope and surface water
through agricultural or landscape irrigation, roof downspouts, septic-tank effluent, or broken
water or sewer lines can also generate landslides. Due to the geophysical or human factors that
16
“Landslides”. SAARC Disaster Management Center. New Delhi. Available online at http://saarcsdmc.nic.in/pdf/landslide.pdf. Accessed March 2011.
45
can induce a landslide event, they can occur in developed areas, undeveloped areas, or any
areas where the terrain was altered for roads, houses, utilities, buildings, and even for lawns.17
Stream and riverbank erosion, road building, or other excavation can remove the toe or lateral
slope and exacerbate landslides. Seismic or volcanic activity often triggers landslides as well.
Urban and rural living with excavations, roads, drainage ways, landscape watering, logging, and
agricultural irrigation may also disturb the solidity of landforms. In general, any land use
changes that affect drainage patterns or that increase erosion or change ground-water levels
can augment the potential for landslide activity.
The frequency of landslides, particularly cut and fill slopes along roads, is due to the geology,
vegetation, climate, soils, and other human factors. There are, on occasion, severe landslide
events that occur in Idaho. There have been eight declared disasters since 1990.18 Since 1976,
major events have had a significant impact on transportation, communities, and natural
resources in 1982, 1986 (x2), 1991, 1996-97, 1997, 1998 (x2), 2000, and 2017 (Table 6).
Table 6) Landslide disaster declarations from 1982-2011 for Idaho counties.
Year
1982
1986
1986
1991
19961997
Month
July
February
March
April
NovemberJanuary
Federal
1997
X
2000
2010
2011
MarchJune
May &
October
June
April
April-May
2017
May
X
1998
X
X
Counties Affected
Boise
Boise
Boise, Elmore, Lewis, Nez Perce, Owyhee
Bonner
Adams, Benewah, Boise, Bonner, Boundary,
Clearwater, Elmore, Gem, Idaho, Kootenia, Latah, Nez
Perce, Owyhee, Payette, Shoshone, Valley, Washington
Benewah, Bonner, Boundary, Kootenia, Shoshone
Year
1982
1986
1986
1991
19961997
May: Lemhi, Nez Perce, Washington; Oct: Boundary
1998
Kootenai
Bonner, Idaho, Shoshone
Bonner, Boundary, Clearwater, Idaho, Nez Perce,
Shoshone and Nez Perce Tribe
Boundary, Bonner, Kootenia, Benewah, Shoshone,
Latah, Clearwater, Idaho, Valley
2000
2010
2011
17
Tetra Tech. DMA 2000 Hazard Mitigation Plan. Onondaga County, New York. April 2010.
18
Idaho Bureau of Homeland Security. April 2011. Available online at www.bhs.idaho.gov.
1997
2017
46
Figure 12) Landscapes prone to landslides (slopes greater than 55%) on the Nez Perce Reservation.
Probability of Future Occurrence
As a frequent natural process, it is likely that landslides across the Reservation will continue to
occur, and with altered weather patterns that are expected from climate change we could see
an increase from historical frequency of major events. Additionally, there may be compounding
47
effects from increased wildfire activities due to a changing climate and an increase in the
number and extent of landslides. Many factors will contribute to increased landslide events
including the removal of vegetation causing soils to become more susceptible to erosion, water
resistance of post-fire soils, and loss of root structures. All of these factors are commonly
associated with second order fire effects, but with prolonged fire seasons and larger wildland
fires as is predicted with our changing climate landslides, mudslides and debris flows will likely
increase as well.
Impacts of Landslide Events
Landslides are a recurrent threat to waterways and highways and a danger to homes, schools,
businesses, and other facilities. The unimpeded movement over roads—whether for
commerce, public utilities, school, emergencies, police, recreation, or tourism—is essential to
the normal functioning of the Reservation. The disruption and dislocation of these or any other
routes caused by landslides can quickly jeopardize travel and vital services. Although small
slumps on cut and fill slopes along roads and highways are relatively common, nearly all of the
more significant landslide risks on the Reservation are associated with the steeper,
mountainous slopes.
Population centers and individual homes in the Clearwater River corridors (Stites, Kooskia,
Kamiah, Greer, Ahsahka, Orofino, Spalding) and Lapwai Creek (Lapwai, Culdesac) have the
highest risk of experiencing slides. However, most of the damage from slides on the
Reservation will likely occur along roadways. Major landslides in communities that are situated
along river corridors could cause property damage, injury, and death and may adversely affect a
variety of resources. For example, water supplies, fisheries, sewage disposal systems, forests,
dams, and roadways can be affected for years after a slide event. The negative economic
impacts of landslides include the cost to repair structures, loss of property value, disruption of
transportation routes, medical costs in the event of injury, and indirect costs such as lost timber
and fisheries. U.S. Highways 95 and 12 have experienced numerous slides of varying severity
that have blocked one or both lanes for several days.
Slides in the river and stream drainages may also block the channel causing water to back up
and spill over into areas not previously at risk to flooding. Numerous communities and homes
could be at risk if this type of event were to occur. In many cases, a slide blocking the water
channel would also cut off emergency access routes as many roads on the Reservations parallel
the streams and rivers.
Value of Resources at Risk
Slides in the identified Clearwater Impact Zone are more likely to be larger and more damaging
as weaknesses in the underlying rock formations give way. Although infrequent, this type of
48
slide has the potential to not only block, but destroy road corridors, dam waterways, and
demolish structures. A number of structures lie within the Impact Zone as well as sections of
U.S. Highway 12 and State Route 13. U.S. Highway 95 only has a short section of landslide prone
slopes in the canyon south of Culdesac, and many of the other highly prone areas within the
Reservation are on secondary roadways. At the time of the development of this plan, an
analysis of the value of structures at risk was not performed. However, Table 7 shows the type
and number of structures found in designated landslide areas across the reservation. In total,
there are only about 20 homes/residential structures and several outbuildings that are in
landslide risk areas. Refer to the maps in this section and the Vulnerable Areas and
Infrastructure for total values at risk on the Nez Perce Reservation.
The cost of cleanup and repairs resulting from slumps along roadways is difficult to estimate
due to the variable circumstances with each incident including the size of the slide and
proximity to a road maintenance shop. Other factors that could affect the cost of the damage
may include culverts, streams, and removal of debris.
Table 7) Structures at risk to landslides on the Nez Perce Reservation.
Structure Type
Homes/Residential Structures
Outbuildings
Total
Count
20
Several
20*
*Value includes countable structures only (outbuildings were not
included).
49
Wildland Fire Profile
Wildland Fire Characteristics
In general, wildland fire behavior describes how fire reacts to available fuels, local topography,
and current weather conditions. The relationships between these three components are
dynamic; changing one condition can often exacerbate the affects that the other conditions
have on fire behavior. As such, fire behavior is often modeled as a triangle with fuels,
topography, and weather serving as the three sides
(Figure 13). Understanding the relationships between
the fire behavior components has important
implications for not only managing an active wildfire but
also mitigating wildfire risk. Since fuel is the only
component that can be managed directly, management
decisions regarding fuel types and fuel loading across
the landscape need to be made based on characteristics
that are inherent of the region -climate and topography.
Strategic fuel breaks, conservation and restoration of
native species, and prescribed burns are examples of
13) Fire Behavior Triangle
management activities that can reduce wildfire risk and Figure
(www.weatherstem.com)
simplify the process of assessing potential wildfire
behavior.
A brief description of each of the fire environment elements follows in order to illustrate their
effect on fire behavior.
Weather
Fire behavior is largely influenced by weather conditions. Wind, moisture levels, temperature,
and relative humidity are all factors that determine the rates and which fuels dry and
vegetation cures. The ignition potential of fuels is also determined by these factors; weather
patterns and trends can be analyzed to determine how likely or easily a certain fuel type will
ignite and if a fire will be sustained. Once started, the behavior of a wildfire is further
determined by atmospheric stability and local and regional weather. As temperature, wind
speed, wind direction, precipitation, storm systems, and prevailing winds all influence fire
behavior, weather is the most difficult component of the fire triangle to predict and interpret.
As observed in the Yarnell Hill fire in Arizona that killed 19 firefighters, a storm cell can cause a
flaming front to change direction abruptly, 90 degrees in the case of the Yarnell Hill fire, and
rapidly accelerate up to speeds of 10 to 15 mph.
50
Topography
Fires burning in similar fuel types will burn differently under varying topographic conditions.
Topography alters heat transfer and localized weather conditions, which in turn influences
vegetative growth and resulting fuels. Changes in slope and aspect can have significant
influences on how fires burn. In General, north slopes tend to be cooler, wetter, more
productive sites. This typically results in heavy fuel accumulations, high fuel moistures, lower
rates of curing for fuels, and lower rates of spread. In contrast, south and west slopes tend to
receive more direct sun and therefore have the highest temperatures, lowest soil and fuel
moistures, and lightest fuels. The combination of light fuels and dry sites leads to fires that
typically display the highest rates of spread. These slopes also tend to be on the windward side
of mountains which means they tend to be “available to burn” for a greater portion of the year.
Slope also plays a significant role in the rate of spread of a fire as fuels upslope from the flaming
front are subjected to preheating which means that they readily combust as the fire draws
closer. The preheating process is exacerbated as slope increases which results in greater rates
of spread and increased flame lengths. Therefore, steep slopes with a south –southwest aspect
generally promote intense fire behavior due to dry fuels and the likelihood of predominant,
westerly winds.
Fuels
In the context of wildfire, fuels describe any organic material, dead or alive, found in the fire
environment. Grasses, brush, branches, logs, logging slash, forest-floor litter, conifer needles,
and buildings are all examples of fuel types. The physical properties and characteristics of fuels
govern how fires burn. Fuel loading, size and shape, moisture content, and continuity and
arrangement all have an effect on fire behavior. In general, the smaller and finer the fuels, the
faster the potential rate of fire spread. Small fuels such as grass, needle litter and other fuels
less than a quarter inch in diameter are most responsible for fire spread. Fine fuels, those with
high surface to volume ratios, are considered the primary carriers of surface fire. As fuel size
increases, the rate of spread tends to decrease due to a decrease in the surface to volume ratio.
Fires in large fuels generally burn at a slower rate but release much more energy and burn with
much greater intensity. This increased energy release, or intensity, makes these fires more
difficult to control.
Fuels are classified by diameter as that has important implications for fuel moisture retention.
The smaller the diameter, the more quickly the moisture content of a given fuel type changes
while larger diameter fuels take longer to change. In terms of fire potential on the landscape
and fire suppression, the amount of time that is required for a fuel type to become volatile is
critical which is why instead of referring to fuels by size, they are referred to as either one hour,
ten hour, 100 hour, or 1000 hour fuels. This method of classifying fuels describes the amount of
51
time required for a particular fuel’s status to change from non-combustible to combustible as a
result of altered moisture levels in the surrounding environment.
History and Extent
In the 1930s, wildfires consumed an average of 40 to 50 million acres per year in the contiguous
United States, according to US Forest Service estimates. By the 1970s, the average acreage
burned had been reduced to about 5 million acres per year. Accounting for the substantial
reduction in burned acreage was an increase in fire suppression efforts and development of
firefighting equipment and strategy. Since 1970, about 3.5 million acres burn annually in the
western U.S.
The potential volatility of a fire season can be predicted from winter snowfall, snowpack
longevity, spring temperatures, and totals precipitation. When winter snowfall is limited and
snowpack melts early due to warm spring temperatures, conditions begin to favor fire activity
as fine fuels dry out and spring storms generate lighting and high winds. Additionally, human
activity increases in natural areas and recreation areas in warm weather months; typically April
through October. This increases the likelihood of a human-caused ignition, particularly in
natural areas where fuels are abundant, that could result in a wildfire, threatening both
populated areas and natural resources.
Fire History
Historically, most plant communities in the state of Idaho were fire-adapted and regularly
burned. Frequent, low intensity fires limited fuel accumulation across the landscape and
contributed to the distribution of native, fire-adapted plant communities. In contrast to modern
day conditions, fire return intervals (the amount of time between fires in a defined area) were
shorter but fires burned with less intensity.
Shorter return intervals between fire events often resulted in less dramatic changes in plant
composition. Across the landscape, fire typically burned 1 to 50 years apart in a given areas
with most fire returning between 5 and 20 years. With infrequent return intervals, plant
communities tended to burn more severely and were replaced by vegetation different in
composition, structure, and age. Native plant communities in this region developed under the
influence of fire, and adaptations to fire are evident at the species, community, and ecosystem
levels.
52
State of Idaho Fire History
The figures in this section only include large or significant wildfires that occurred in the state of
Idaho between 2000 and 2017; it is likely that fire personnel responded to a far greater number
of fires in each county during that time period. The narrative in this section was developed
around the values displayed in the maps that follow and therefore is not representative of all
fire activity that occurred in Idaho from 2000 to 2017.
Historically, the State of Idaho has had very active fire seasons. Long periods of hot and dry
weather in summer months exacerbate fire conditions with some years being more extreme
than others. In the last decade, the 2012 fire season was the most significant as large fires
burned more than 2.5 million acres across the state. However, several years, specifically 2009,
were relatively mild and fewer than 250,000 acres burned as a result of large fires. Figure 14
shows the locations and perimeters of large wildfires that occurred in Idaho between 2000 and
2017.
Some counties experienced more large fires than other counties between 2000 and 2017. Of
the 44 counties in Idaho, 16 counties, half of which are located in the Panhandle, experienced 1
to 25 wildfires (Figure 15). Elmore and Owyhee counties in southwest Idaho experienced the
greatest number of fires during that time period at 312 and 306 large fires, respectively. Also
experiencing a significant number of large wildfires was Idaho County with 257 fires and Cassia
County with 201 fires. The counties in the southeastern part of the state appeared to have the
greatest number of large fires while those in the northern portion experienced the fewest.
In addition to having the greatest number of large fires between 2000 and 2017, the most
acreage also burned in Owyhee and Idaho counties at over 2.1 million and 2.0 million acres,
respectively. The histogram in Figure 16 shows county frequency by acreage burned during that
time period. Eight different counties fell in the 250,001 to 500,000 acres-burned category, and
only two counties fell in the 2.25 million acres or more range.
53
Figure 14) Locations and perimeter of large wildfires that occurred in Idaho between 2000 and 2017.
54
Figure 15) Number of fires by county in the State of Idaho from 2000 to 2017.
55
Figure 16) Acreage burned by wildfire by county for the State of Idaho from 2000 to 2017.
56
History of Fire on the Nez Perce Reservation
In 2015 there were a number of large fires in and around the Reservation; the fires included in
the Clearwater and Municipal Complex fires burned 68,127 acres in total: the Fisher Fire
located south of Orofino burned in the canyons before reaching agricultural lands and burned
18,889 acres, in the Kamiah area the Lawyer 2 Fire consumed 41,195 acres, the Municipal Fire
burned 1,770 acres, the Lolo 2 Fire burned 6,200 acres, and the Old Greer Fire burned 73 acres.
Because these fires occurred primarily in the wildland urban interface, lives, homes, and
property value were threatened. Numerous buildings were destroyed along with millions of
board feet of privately owned timber, livestock fences, crops, and other infrastructure. As a
secondary effect, there have been and continue to be erosion issues along roadways and in the
canyonlands. Figure 17 shows historical fires that have occurred on the Reservation.
Reservation fires in 2007 included the Russell Ridge (Hatwai) Fire at 4,800 acres, Coyote Creek
(Grade) Fire near Spaulding at 3,300 acres and the loss of one tribal residence, and the Central
Grade Fire at 100 acres. Multiple fires have also occurred in the Craig Mountain area, including
the Chimney Creek Complex (51,000 acres) in 2007, Dry Creek (5,700 acres), and the Kurby Fire
(550 acres). In 2000 as a result of a large fire season, the Federal government declared several
counties, including Clearwater, Idaho, and Lewis, disaster areas.
Local knowledge suggests that Native Americans did frequently perform burns which played an
important role in shaping the vegetation throughout the county. During the public meetings,
participants shared information about previous fire events. This information is consistent with
DOI ignition data for the reservation which suggests that the majority of the ignitions reported
on the Reservation from 2007 to 2017 were human caused (265) and that natural ignition
sources (lighting strikes) were less common (96). Refer to Table 8 for more detailed ignition
source information for the reservation.
Wildland Fire Risk
Using data such as slope, aspect, vegetation type, and density, an assessment of wildland risk
was completed by the Nez Perce Tribe GIS Department. While the entire Reservation is at risk
to various types of ignitions, the communities along the Clearwater River drainage including
Stites, Kooksia, Kamiah, Woodland, Greer, Orofino, Ahsahka, Peck, and Lenore have the
greatest potential for impacts. Fires in these areas are more likely to grow beyond initial attack
due to access and topography and will likely have higher rates of spread due to topography and
fuel type. Nonetheless, scattered homes and other outlying structures located in the lower risk
areas are not without risk entirely. Fires in agricultural or rangeland dominated areas can also
spread very quickly. Lower population may also increase the risk of an ignition going
unreported for a longer period of time and it may take longer for firefighters to respond.
57
Acres Burned
Number of Fires
Table 8) Number of fires and acreage burned by ignition source from 2007 to 2017 on the Nez Perce Reservation, ID. Data is from the Department of the Interior Wildland
Fire Information Management System.
Cause
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
Total
Percentage
Campfire
3
1
1
0
1
1
0
1
1
1
1
11
3%
Smoking
4
0
0
0
0
4
0
0
0
1
3
12
3%
Fire Use
10
2
2
4
2
0
2
7
1
2
9
41
11%
Incendiary
12
5
3
4
5
0
5
6
0
0
2
42
12%
Equipment
11
10
3
3
6
3
9
7
9
0
1
62
17%
Railroads
0
1
0
0
1
0
1
0
0
3
0
6
2%
Juveniles
15
9
4
0
3
1
2
3
2
0
0
39
11%
Miscellaneous
7
4
5
1
0
2
4
8
8
2
11
52
14%
Human Sub-total
62
32
18
12
18
11
23
32
21
9
27
265
73%
Natural (Lightning)
5
8
11
15
4
3
1
10
30
2
7
96
27%
Total
67
40
29
27
22
14
24
42
51
11
34
361
100%
Campfire
3.5
0.1
2
0
0.1
0.1
0
0.1
0.2
0.1
0.1
6
0%
Smoking
0.5
0
0
0
0
3.3
0
0
0
0.1
5.2
9
0%
Fire Use
289
7.7
27.5
574.6
5.8
0
10.2
10.8
2
5.4
35.1
968
1%
Incendiary
21.6
1.2
5.5
1.8
231.6
0
676.5
3.9
0
0
11.1
953
1%
Equipment
4013.3
13.9
5.5
98.2
132.3
277.6
339.2
2265.6
162.4
0
0.1
7308
9%
Railroads
0
2
0
0
4.5
0
299
0
0
8
0
314
0%
Juveniles
4.8
1.5
0.6
0
1.5
0.1
0.9
1.6
0.2
0
0
11
0%
Miscellaneous
13.2
4963.8
0.9
4
0
1.1
2.2
227.5
1765.1
0.2
33.2
7011
8%
Human Sub-total
4345.9
4990.2
42
678.6
375.8
282.2
1328
2509.5
1929.9
13.8
84.8
16580
19%
Natural (Lightning)
35.5
804.1
45
9
3.2
26.1
10
7.9
60795.6
1829.2
5043
68608
81%
Total
4381.4
5794.3
87
687.6
379
308.3
1338
2517.4
62725.5
1843
5127.8
85188
100%
58
Figure 17) Fire history map of the Nez Perce Reservation.
Fire susceptibility throughout northern Idaho dramatically increases in late summer and early
autumn as vegetation dries out, decreasing plant moisture content and increasing the ratio of
dead fuel to living fuel. However, various other factors, including humidity, wind speed and
direction, fuel load and fuel type, and topography, can contribute to the intensity and spread of
wildland fires. Figure 18 shows high risk fire areas on the Nez Perce Reservation.
59
Figure 18) Wildland fire risk map for the Nez Perce Reservation.
60
Probability of Future Occurrence
Lightning ignitions are common on the Reservation and typically occur along ridgetops, but
negligence and arson, as well other human causes, account for the majority of ignitions that
occur on the Reservation. These fires are often quickly controlled by local resources and rarely
grow beyond an acre in size.
Larger fires, requiring additional resources beyond initial attack, are less common, but can
occur annually. Based on past history, this type of fire is likely to occur on and/or near the
Reservation approximately every 3 years.
Impacts of Wildfire Events
Unlike other natural disasters, the effects of a wildfire, with the exception of smoke and fire
brands, are localized and can be contained with an effective management strategy. However,
even if a fire is successfully contained, communities in proximity to the fire may still experience
disruptions as municipal resources are diverted to suppression efforts. Should a wildfire grow
beyond the capabilities of local fire agencies, other in-state resources as well and federal
resources may be requested for additional support. Local residents with property in the path of
wildland fire will likely suffer the greatest impacts through loss of structures, personal property,
and/or the value of any timber or agricultural crops on their land.
In the event that a wildfire exhibits extreme behavior, it may be necessary for some
communities to evacuate. The evacuation of densely populated areas will require extensive
traffic control, safe routes that are capable of accommodating high traffic volumes, and
additional resources and facilities will be required should evacuees need emergency shelter in
the event that they do not have alternate lodging options. Accommodations for evacuees will
place additional demand on community resources and may further disrupt neighboring
communities. Local businesses could be affected in several ways, particularly if access to
business districts are limited or restricted altogether. In addition to heavy smoke, closures of
natural or recreational areas may also have adverse impacts on the tourist industry.
Wildland fires, big and small, are dangerous to both Tribal residents and emergency response
personnel. Wildland fire suppression activities have a very high frequency of injuries, such as
heat exhaustion and smoke inhalation, and have caused numerous deaths nationwide. Fire
events often result in a multi-department and agency response effort; thus, coordinating
activities and ensuring everyone’s safety is paramount.
The Reservation has sensitive populations such as elders and children, who may be affected by
air quality during a wildland fire. Smoke and particulates can severely degrade air quality,
triggering health problems. In areas heavily impacted by smoke, people with breathing
61
problems might need additional services from doctors, emergency rooms, or the need to find
locations with clean air.
The environmental impacts from a fire are dependent on the vegetation present and the
intensity of the fire. Most of the rangeland and forest ecosystems present on the Reservation
are adapted to periodic fire events and benefit from occasional, low intensity burns. On the
other hand, overcrowded forest conditions or areas infested with more susceptible weeds will
likely burn much more intensely than occurred historically. These types of fires tend to result in
a high rate of mortality in the vegetation potentially resulting in species conversion and often
adversely impact soil conditions. High intensity fires are also much more dangerous and
difficult to suppress. Vegetation on the Nez Perce Reservation is currently 92% coniferous
forest. Under fire suppression, coniferous forest cover is expected to increase 19.
Table 9) Projected change in vegetation composition under fire suppression is reported as the
percent of the Nez Perce Reservation covered by different vegetation types for 20 models of
vegetation.
Time Period
20-Model Median Vegetation Class
1971-2000
92% Conifer Forest
8% Woodland Savanna
2010-2039
(Higher Emissions)
96% Conifer Forest
4% Woodland/Savanna
2040-2069
(Higher Emissions)
98% Conifer Forest
2% Woodland Savanna
2070-2099
(Higher Emissions)
98% Conifer Forest
1% Woodland/Savanna
In addition, climate change is expected to increase annual summer temperatures up to 7.5
degrees Fahrenheit by mid-century, and up to 12.1 degrees Fahrenheit by the end of the
century, lengthen the wildfire season, increase the annual days of extreme fire danger, and
decrease summer soil moisture resulting in drier, hotter, more vulnerable forests, and more
extreme fire danger (Table 10, Figure 19). With an increase in average annual summer
temperature, it is also likely that the region will experience a greater number of extreme fire
danger days (Figure 20); this is also reflected in the projected annual heat accumulation over 50
degrees Fahrenheit which is also expected to increase through 2099 (Figure 21).
19
Krosby, M.B., Hegewisch, Norheim, R.,Mauge, G., Yazzie,K., Morgan, H.,"Tribal Climate Tool" web tool. Climate
Impacts Group(https://cig.uw.edu/our-work/decision-support/building-tribal-capacity-for-climate-changevulnerability-assessment/) and NW Climate Toolbox (https://climatetoolbox.org/) accessed on [October 4, 2018].
62
Additionally, the fire season is expected to intensify and become more extreme in surrounding
states and California. Wildfire suppression and control in the western United States is a
coordinated interagency effort in which resources are distributed on a first-come, first-served
basis. The earlier and more extreme fire seasons in California have already impacted the
availability of fire-fighting equipment and personnel in the Northwest because the fire season
starts earlier in California than it does in the northwest. This could impact the ability of local
fire-fighters to access assistance during wildfire events (Nez Perce Forestry and Fire).
Table 10) Maximum projected daily temperatures and net temperature change for July through August for the Nez
Perce Reservation, ID per the Tribal Climate Change Tool.
Time Period
Model Average Temperature
Change from Historical
Historical
80.0 °F
2010-2039
(Higher Emissions)
83.5 °F
+ 3.5°F
2040-2069
(Higher Emissions)
87.5 °F
+ 7.5°F
2070-2099
(Higher Emissions)
92.0 °F
+ 12.1°F
Figure 19) Maximum projected daily temperatures for July through August for the Nez Perce Reservation, ID
per the Tribal Climate Change Tool.
63
Figure 20) Number of extreme fire danger days by time period projected for the Nez Perce Reservation, ID per the
Tribal Climate Change Tool.
Figure 21) Annual heat accumulation above 50 degrees Fahrenheit projected for the Nez Perce Reservation, ID per the
Tribal Climate Change Tool.
64
Climate change will also affect seasonal soil moisture levels which are expected to steadily
decline. Compared to a historic value of 23.9 inches, average soil moisture levels for July
through September are expected to drop to 20.8 inches by 2069, a 13% decrease (Table 11).
Soil moisture levels are projected to continue to decrease, averaging less than 20 inches per
year by 2099 (Figure 22). Figure 23 is a map that compares historic soil moisture values to those
projected for the period 2010 to 2039 while Figure 24 displays differences between historic
values and projections for 2040 to 2069.
Table 11) Projected change in Jul. - Sept. total soil moisture was averaged over the Clearwater Basin, and reported as an
average over 10 models of hydrology.
Years (Emission Scenario)
Model Average Soil Moisture
1971-2000 (Past)
23.9 inches
2040-2069 (Higher Emissions)
20.8 inches
Change
-3.1 (-13%)
Figure 22) Projected change in Jul. - Sept. total soil moisture was averaged over the Clearwater Basin, and reported as an
average over 10 models of hydrology.
65
Figure 23) Projected change in Jul. - Sept. total soil moisture was averaged over the Clearwater Basin for 2010-2039, and
reported as an average over 10 models of hydrology
66
Figure 24) Projected change in Jul. - Sept. total soil moisture was averaged over the Clearwater Basin for 2040-2069, and
reported as an average over 10 models of hydrology
67
Value of Resources at Risk
It is difficult to estimate the potential losses across the Reservation, typically structures located
in forested areas without an adequate defensible space or fire-resistant landscaping have the
highest risk of loss. Nevertheless, homes and other structures located in the grasslands or
agricultural regions are not without wildfire risk. Grass fires are often the most dangerous due
to high rates of spread. Fires in this fuel type are considered somewhat easier to suppress given
the right resources, but they can also be the most destructive. Homes along the perimeter of
the community would have the highest risk due to their adjacency to wildland fuels. Table 12
summarizes the type and number of structures located in high risk wildfire areas. Most of the
structures at risk, approximately 5,400 structures, are classified as homes/residential while
almost 500 commercial and commercial-type structures are at risk.
Table 12) Structures located in high risk wildfire areas on the Nez
Perce Reservation.
Structure Type
Homes/Residential
Commercial and Commercial-type
Other School Buildings
Schools
Historical Structures
Health Clinic
Prison
Outbuildings
Total
Count
5,345
493
25
9
2
1
1
Hundreds
5,876
*Value includes countable structures only (outbuildings were not
included).
68
Volcanic Eruption Profile
Hazard Description and History
An explosive eruption from a composite volcano blasts
solid and molten rock fragments (tephra) and volcanic
gases into the air with tremendous force. The largest rock
fragments (bombs) usually fall back to the ground within
2 miles of the vent. Small fragments (less than about 0.1
inch across) of volcanic glass, minerals, and rock (ash) rise
high into the air, forming a huge, billowing eruption
column.
Eruption columns can grow rapidly and reach more than
12 miles above a volcano in less than 30 minutes, forming
an eruption cloud. The volcanic ash in the cloud can pose
a serious hazard to aviation. Ash related engine failures
have led to restriction on travel through ash clouds.
Following the eruption of Eyjafjallajökull in 2010, which
disrupted one of the busiest airways in the world, over
100,000 flights were cancelled, leading to billions in
Figure 25) USGS Volcanic Hazards and Exposure
economic losses.20 During the 56 years between 1953
and 2009 there were 94 occasions when aircraft encountered ash, with 79 of those incidents
caused some degree of engine damage and 26 resulted in significant engine damage. 21 Figure
25 demonstrates the relationship between volcanic hazards and the exposure of people and
property and how those factors are used to quantify risk.
Large eruption clouds can extend hundreds of miles downwind, resulting in ash fall over
enormous areas; the wind carries the smallest ash particles the farthest. Ash from the May 18,
1980, eruption of Mount St. Helens, Washington, fell over an area of 22,000 square miles in the
Western United States. Heavy ash fall can collapse buildings, and even minor ash fall can
damage crops, electronics, and machinery.
Volcanoes emit gases during eruptions. Even when a volcano is not erupting, cracks in the
ground allow gases to reach the surface through small openings called fumaroles. More than
ninety percent of all gas emitted by volcanoes is water vapor (steam), most of which is heated
20
Morton, M.C., 2017. “Of airplanes and ash clouds: What we’ve learned since Eyjafjallajökull.” Earth. Available online at:
https://www.earthmagazine.org/article/airplanes-and-ash-clouds-what-weve-learned-eyjafjallaj%C3%B6kull
21
Guffanti, M., et al., 2010. “Encounters of Aircraft with Volcanic Ash Clouds: A Compilation of Known Incidents, 1953—2009.” USGS Data
Series 545, ver. 1.0, 12 p., Available online at: http://pubs.usgs.gov/ds/545
69
ground water. Other common volcanic gases are carbon dioxide, sulfur dioxide, hydrogen
sulfide, hydrogen, and fluorine. Sulfur dioxide gas can react with water droplets in the
atmosphere to create acid rain, which causes corrosion and harms vegetation. Carbon dioxide is
heavier than air and can be trapped in low areas in concentrations that are deadly to people
and animals. Fluorine, which in high concentrations is toxic, can be adsorbed onto volcanic ash
particles that later fall to the ground. The fluorine on the particles can poison livestock grazing
on ash-coated grass and also contaminate domestic water supplies.22
Table 13) List of active volcanos of Highest Priority and High Priority within the U.S., Source: USGS
Region
Highest Priority
High Priority
Alaska
Akutan, Amak, Amukta, Bogoslof,
Cleveland, Fourpeaked, Kasatochi,
Kiska, Makushin, Recheshnoi,
Redoubt, Seguam, Vsevidof,
Yantarni, Yunaska
Black Peak, Chignagak, Churchill,
Dana, Douglas, Dutton, Edgecumbe,
Hayes, Kaguyak, Kupreanof, Spurr,
Wrangell
Washington
Glacier Peak, Mount Baker, Mount
Ranier, Mount St. Helens
Mount Adams
Oregon
Crater Lake, Mount Hood, Newberry,
Three Sisters
California
Lassen Volcanic Center, Mount
Shasta
Wyoming
Clear Lake, Mono-Inyo Craters, Mono
Lake Volcanic Field, Medicine Lake
Yellowstone
While there are numerous volcanos of concern in the U.S. (Table 13), the volcanoes of the
Cascade Range, which stretches from northern California into British Columbia, have produced
more than 100 eruptions, most of them explosive, in just the past few thousand years.
However, individual Cascade volcanoes can lie dormant for many centuries between eruptions,
and the great risk posed by volcanic activity in the region is therefore not always apparent.
When Cascade volcanoes do erupt, high-speed avalanches of hot ash and rock (pyroclastic
flows), lava flows, and landslides can devastate areas 10 or more miles away; and huge
mudflows of volcanic ash and debris, called lahars, can inundate valleys more than 50 miles
downstream. Falling ash from explosive eruptions can disrupt human activities hundreds of
miles downwind, and drifting clouds of fine ash can cause severe damage to jet aircraft even
22 Myers, Bobbie, et al.
“What are Volcano Hazards?” U.S. Geological Survey. Vancouver, Washington. July 2004.
70
thousands of miles away. Erupting Cascade volcanoes are more prone than other U.S.
volcanoes to explosive volcanic activity, resulting in pyroclastic flows. These are hot, often
incandescent mixtures of volcanic fragments and gases that sweep along close to the ground at
speeds up to 450 mph.
Figure 26) Location and eruption-frequency of volcanos in the Cascade Mountain Range.
71
Because the population of the Pacific Northwest is rapidly expanding, the volcanoes of the
Cascade Range in Washington, Oregon, and northern California are some of the most
dangerous in the United States. Although Cascade volcanoes do not often erupt (on average,
about two erupt each century), they can be dangerous because of their violently explosive
behavior, their permanent snow and ice cover that can fuel large volcanic debris flows (lahars),
and their proximity to various critical infrastructure, air routes, and populated areas.23
The Cascade Range has more than a dozen potentially active volcanoes (Figure 26). Cascade
volcanoes tend to erupt explosively, and on average two eruptions occur per century—the
most recent were at Mount St. Helens, Washington (1980–86 and 2004–8), and Lassen Peak,
California (1914–17). On May 18, 1980, after 2 months of earthquakes and minor eruptions,
Mount St. Helens, Washington, exploded in one of the most devastating volcanic eruptions of
the 20th century. Although less than 0.1 cubic mile of molten rock (magma) was erupted, 57
people died, and damage exceeded $1 billion. Fortunately, most people in the area were able
to evacuate safely before the eruption because public officials had been alerted to the danger
by U.S. Geological Survey (USGS) and other scientists. To help protect the Pacific Northwest’s
rapidly expanding population, USGS scientists at the Cascades Volcano Observatory in
Vancouver, Washington, monitor and assess the hazards posed by the region’s volcanoes.24
Probability of Future Occurrence
The Pacific Coast lies along the Ring of Fire which has produced 22 of the 25 largest volcanic
eruptions over the last roughly 11,000 years25. The USGS studies and monitors many of the
active volcanos in Washington State. Studies have shown that Glacier Peak has erupted an
estimated 5 times in the last 13,000 years, likewise. Figure 26 shows the location and eruptionfrequency of each volcano along the Cascade Mountains for the past 4000 years. While not a
common occurrence eruption from the Cascade Volcanos occur, on average, two every century.
23 Dzurisim, Dan, et al.
“Living with Volcanic Risk in the Cascades.” U.S. Geological Survey – Reducing the Risk from Volcano Hazards. USGS.
Vancouver, Washington. 1997.
24 Dzurisim, Dan, et al.
“Living with Volcanic Risk in the Cascades.” U.S. Geological Survey – Reducing the Risk from Volcano Hazards. USGS.
Vancouver, Washington. 1997.
25 Oppenheimer, Clive. 2011. Eruptions that Shook the World. University of Cambridge.
72
Impacts of Volcanic Eruption
The most likely impact from a volcanic
eruption that would affect the Nez Perce
Tribe would be ash fall from one of the
many active volcanoes along the Cascade
Mountain Range. Volcanic ash is a
mixture of small particles of rock and
glass fragments, winds can carry ash
thousands of miles from the eruption
site26. Prolonged exposure to ash can
poses a health risk to people with
respiratory conditions, children, and the
elderly, leading to increased hospital
visits and increased need/access to
medications. Ash build up on rooftops of
building can cause collapse, potentially
causing injury or death. Water quality and
wastewater management can be Figure 27) Historic ash fall map for the Pacific Northwest. Kenedi,
impacted or disrupted by ashfall. In C.A. et al. USGS 2000.
addition to the risk to human health, ash can cause disruption to everyday activities; vehicle
engines can become clogged with ash causing them to stall, power distribution systems can fail,
communication systems may be disrupted due to the scattering or absorption of radio signals,
crop damage and effects on livestock can range from minimal to severe 265. Disruption to
transportation systems through the closing of roadways and airports, can potentially result in
an economic loss and stranded citizens.
There are no active volcanoes on the Reservation; however, communities in this area could be
directly affected by an eruption from any one of the Cascade volcanoes. During an eruption,
such as the 1980 eruption of Mount St. Helens, the Reservation is not likely to be directly
affected by lava flows, pyroclastic flows, landslides, or lahars; however, this region may be
indirectly impacted due to damming of waterways, reduced air and water quality, acid rain, and
ash fallout (Figure 27).
26
Kenedi, C. A., Brantley, S.R. Hendley II, J.W., Stauffer, P.H., (2000). Volcanic Ash Fall – A “Hard Rain” of Abrasive
Particles. USGS. Retrieved from: https://pubs.usgs.gov/fs/fs027-00/
73
Value of Resources at Risk
It is difficult to estimate the potential losses across the Reservation from a volcanic eruption,
the main impact to eastern Washington, Idaho and Oregon from Mount St. Helens in 1980
eruption was ash accumulation on the roadways. Interstate 90 that runs from Spokane to
Seattle was closed for a week, and multiple highways closed throughout northern Idaho. In
addition to road closures the Portland International Airport had to stop flights for a few days.
Towns, including Moscow and St. Maries, Idaho enacted 10 mph speed limits and in many areas
transportation came to a complete standstill leaving travelers stranded. Disruption to the
transportation systems also lead to economic losses as business slows and transportation of
merchandise are either slowed or stopped. In Idaho alone the cost to businesses, clean-up, and
vehicle damage was estimated in the tens of millions of dollars.27 Structural damage to
buildings is not common from ashfall, but depending on thickness of ash and structural design
of the build it can occur. A layer of ash four inches thick can weigh between 120 to 200 pounds
per square yard, and wet ash can weigh double25.
Sensitive populations; elderly, children, and those that have respiratory issues, are susceptible
to the fine particulates from the ash fall. The effects of inhaled ash are dependent on the
composition of ash, size distribution of the inhaled material, the inhaled dose, and whether the
individual had pre-existing respiratory conditions28. Refer to the Vulnerable Areas and
Infrastructure for more information about total values at risk on the reservation in the event of
an eruption.
27
Volcano, 1980 Mount St. Helens: Idaho Office of Emergency Management. Retrieved from:
https://ioem.idaho.gov/Pages/History/VolcanoHistory.aspx
28
Buist, S.A., et al. (1986). The Development of a Multidisciplinary Plan for Evaluation of Long-term Health Effects
of the Mount St. Helens Eruptions.
74
Hazardous Materials
The following information was excerpted from the 2009 Nez Perce Tribe HMP.
Hazard Description and History
Hazardous materials may include hundreds of substances that pose a significant risk to humans.
These substances may be highly toxic, reactive, corrosive, flammable, radioactive, or infectious.
Numerous Federal, State, and local agencies including the U.S. Environmental Protection
Agency (EPA), U.S. Department of Transportation, National Fire Protection Association, FEMA,
U.S. Army, and the International Maritime Organization regulate hazardous materials.
Hazardous material releases may occur from any of the following:
•
Fixed site facilities (such as refineries, chemical plants, storage facilities, manufacturing,
warehouses, wastewater treatment plants, dry cleaners, automotive sales/repair, gas
stations, etc.)
•
Highway and rail transportation (such as tanker trucks, chemical trucks, railroad tankers)
•
Air transportation (such as cargo packages)
•
Pipeline transportation (liquid petroleum, natural gas, and other chemicals)
Unless exempted, facilities that use, manufacture, or store hazardous materials in the United
States fall under the regulatory requirements of the Emergency Planning and Community Right
to Know Act (EPCRA) of 1986, enacted as Title III of the Federal Superfund Amendments and
Reauthorization Act (42 United States Code 11001–11050; 1988). Under EPCRA regulations,
hazardous materials that pose the greatest risk for causing catastrophic emergencies are
identified as EHSs. These chemicals are identified by the EPA in the List of Lists – Consolidated
List of Chemicals Subject to the Emergency Planning and Community Right-to-Know Act (EPCRA)
and Section 112 of the Clean Air Act. Releases of EHSs can occur during transport and from fixed
facilities. Transportation-related releases are generally more troublesome because they may
occur anywhere, including close to human populations, critical facilities, or sensitive
environmental areas. Transportation-related EHS releases are also more difficult to mitigate
due to the variability of locations and distance from response resources.
In addition to accidental human-caused hazardous material events, natural hazards may cause
the release of hazardous materials and complicate response activities. The impact of
earthquakes on fixed facilities may be particularly serious due to the impairment or failure of
the physical integrity of containment facilities. The threat of any hazardous material event may
be magnified due to restricted access, reduced fire suppression and spill containment, and even
complete cut-off of response personnel and equipment. In addition, the risk of terrorism
75
involving hazardous materials is considered a major threat due to the location of hazardous
material facilities and transport routes throughout communities and the frequently limited
antiterrorism security at these facilities.
On behalf of several Federal agencies including the EPA and U.S. Department of Transportation,
the National Response Center serves as the point of contact for reporting oil, chemical,
radiological, biological, and etiological discharges into the environment within the United
States.
The National Response Center Web-based query system of non-Privacy Act data shows that
between 2005 and 2009, three oil and chemical spills have occurred in the incorporated
communities within the Reservation boundaries.
Probability of Future Occurrence
A facility must report to the EPA’s Toxics Release Inventory data annually if the facility has:
•
•
•
•
Has 10 or more full-time employees, and
Manufactures or processes over 25,000 pounds of the approximately 600 designated
chemicals or 28 chemical categories specified in the regulations, or uses more than 10,000
pounds of any designated chemical or category, and
Engages in certain manufacturing operations in the industry groups specified in the U.S.
Government Standard Industrial Classification Codes (SIC) 20 through 39, or
Is a federal facility which are all now required to report per the August, 1995 Executive
Order signed by President Clinton.
According to the EPA’s Toxic Release Inventory data and as shown in Table 14, the EPA
currently regulates 21 facilities within the above 12 communities that are permitted to
discharge to water. 39 facilities are also permitted to handle hazardous waste. However, while
several of the small, fixed facilities (e.g., body shops) have varying uses of hazardous chemicals,
in general these facilities do not pose a significant risk to the Reservation.
In addition to fixed facilities, hazardous material events have the potential to occur along
Highway 95, Highway 12, and railroads. The trucks and trains that use these transportation
arteries commonly carry a variety of hazardous materials including gasoline, other crude oil
derivatives, and other chemicals known to cause human health problems. The Clearwater River
and Lapwai Creek are the two waterways most vulnerable to hazardous material transportation
incidents.
Based on previous occurrences, the likelihood of a small oil or chemical spill occurring within
the Reservation is every 2 years. However, more comprehensive information on the probability
and magnitude of hazardous material events from all types of sources (such as fixed facilities or
76
transport vehicles) is not available. Wide variations among the characteristics of hazardous
material sources and among the materials themselves make such an evaluation difficult.
Table 14) EPA-regulated facilities in the incorporated communities within the Reservation boundaries.
Permitted
Toxic
Hazardous
Discharges
Releases
Waste
to Water
Reported
Handler
Ahsahka
2
0
2
Craigmont
1
0
5
Culdesac
6
0
3
Ferdinand
1
0
1
Kamiah
3
1
12
Kooksia
0
0
0
Lapwai
4
0
5
Nez Perce
0
0
1
Orofino
2
0
7
Reubens
0
0
2
Spalding
1
0
1
Stites
1
0
0
Source: EPA Environmental Facts Multisystem, 2009
Location
Active or
Archived
Superfund
0
0
0
0
0
0
0
0
0
0
0
0
Air Releases
Reported
0
0
0
0
4
0
0
0
2
0
0
0
Impacts of Hazardous Materials Release
While it is beyond the scope of this HMP to evaluate the probability and magnitude of
hazardous material events in the incorporated communities within the Reservation in detail, it
is possible to determine the exposure of population, buildings, and critical facilities should such
an event occur. Of the facilities that were required to file an annual EPA Tier II Material
Inventory Report because of the presence of hazardous materials, 11 were identified as having
EHSs. The substances recorded at these facilities include common hazardous substances, mainly
sulfuric acid. EHSs, as shown in Figure 28, pose the greatest risk for causing catastrophic
emergencies. Areas at risk for hazardous material events include any community that has an
EHS facility and any area within a 1-mile radius of Highway 95, Highway 12, and railroads.
Values of Resources at Risk
Per the analysis performed for the 2009 HMP:
Within the community-wide buffer around the 11 EHS sites approximately 15 percent of the
tribal population is exposed. This includes 349 tribal members, 100 residential buildings (worth
$7.4 million), and 1 critical facility (worth $102,700). These figures are for all 11 EHS facilities
and, therefore, overstate the exposure since the probability of all 11 facilities having an event
77
simultaneously is very low. These facilities are predominantly located within industrial and
public facility zoned areas.
Figure 28) Environmentally hazardous substance (EHS) facilities and transportation routes on the Nez Perce Reservation.
Within the 1-mile buffer around the transportation facilities, over 80 percent of the tribal
population is exposed to a hazardous material transport event. This buffered transport area
includes 1966 tribal members, 418 residential buildings (worth $30.7 million), and all 21 critical
78
facilities (worth $28.8 million). As above, these figures are for the entirety of the transportation
corridors
This text is long and has been trimmed here. Open the source document for the complete record.
This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.