WATER QUALITY STANDARDS (2025)
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WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE
SOUTHERN UTE INDIAN
RESERVATION
4/24/2025
SOUTHERN UTE INDIAN TRIBE
ENVIRONMENTAL PROGRAMS DEPARTMENT
These water quality standards establish water quality goals for water
bodies on the Southern Ute Indian Reservation and provide the legal
basis for regulatory pollution controls.
WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
CONTENTS
1
PURPOSE, AUTHORITY, AND APPLICABILITY ................................................................. 1
1.1 Purpose ........................................................................................................................................... 1
1.2 Authority.......................................................................................................................................... 2
1.3 Severability .................................................................................................................................... 2
1.4 Applicability................................................................................................................................... 2
1.5 Clean Water Act Program Implementation in Cooperation with EPA ................................ 3
1.6 Inquiries, Correspondence, and Notifications to the Tribe .................................................... 3
1.7 Definitions ....................................................................................................................................... 3
2
IMPLEMENTATION OF STANDARDS ................................................................................ 7
2.1 Critical Conditions ......................................................................................................................... 8
2.2 Water Rights .................................................................................................................................. 8
3
TRIENNIAL REVIEW ........................................................................................................... 8
4
MIXING ZONES AND DILUTION POLICY ......................................................................... 9
4.1 Purpose ........................................................................................................................................... 9
4.2 Implementation .............................................................................................................................. 9
5
DESIGNATED USES .......................................................................................................... 10
5.1 Designated Use Codes .............................................................................................................. 11
5.2 Designated Uses Definitions ..................................................................................................... 11
5.3 Stream Segmentation Criteria ................................................................................................. 12
5.4 Assigning Designated Uses ....................................................................................................... 12
5.5 Use Attainability Analyses........................................................................................................ 13
5.6 Changing Use Designations ...................................................................................................... 14
5.7 Surface Water Use Designations for Tribal waters ............................................................ 14
5.8 Intermittent AND EPHEMERAL Waters ................................................................................... 22
5.9 Tribal waters Subject to Use Attainability Analyses ........................................................... 22
6
NARRATIVE WATER QUALITY CRITERIA ....................................................................... 22
6.1 Criteria ......................................................................................................................................... 23
6.2 Implementation ........................................................................................................................... 23
7
NARRATIVE BIOLOGICAL CRITERIA .............................................................................. 24
7.1 Criteria ......................................................................................................................................... 24
7.2 Implementation ........................................................................................................................... 24
8
NUMERIC CRITERIA......................................................................................................... 25
8.1 Establishing Numeric Criteria ................................................................................................... 25
8.2 Potable and Industrial Water Supply.................................................................................... 26
8.3 Primary Contact Recreation ..................................................................................................... 26
8.4 Secondary Contact Recreation ................................................................................................ 27
8.5 Aquatic Life ................................................................................................................................. 27
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8.6 Hardness-Dependent Criteria for Metals .............................................................................. 27
8.7 Ammonia Numerical Criteria for All Segments Designated for Aquatic Use ................. 29
8.8 Selenium Aquatic Life Criteria for Fresh Waters ................................................................. 30
9
NUMERIC CRITERIA TABLES ........................................................................................... 30
9.1 Numeric Criteria for Aquatic Life............................................................................................ 31
9.2 Numeric Criteria for Human Health ........................................................................................ 33
10
WATER QUALITY STANDARDS FOR WETLANDS ........................................................ 40
11
OUTSTANDING TRIBAL RESOURCE WATERS .............................................................. 40
12
ANALYTICAL METHODS ............................................................................................... 42
13 ANTIDEGRADATION REVIEW POLICIES AND PROCEDURES ..................................... 42
13.1 Antidegradation Policy .......................................................................................................... 42
13.2 Antidegradation Implementation Procedures .................................................................... 43
14 VARIANCES FROM WATER QUALITY STANDARDS ................................................... 43
14.1 Application ............................................................................................................................... 43
14.2 Requirements for a Variance ................................................................................................ 44
Tables
Table 1. Designated Use Codes ......................................................................................................................................... 11
Table 2. Designated Uses for the Pine River, Wetlands sustained through Hydrologic and Hydraulic
Connections and Associated Perennial Tributaries.......................................................................................................... 15
Table 3. Designated Uses for the Animas River, Wetlands sustained through Hydrologic and Hydraulic
Connections and Associated Perennial Tributaries. ...................................................................................................... 16
Table 4. Designated Uses for the Florida River, Wetlands sustained through Hydrologic and Hydraulic
Connections and Associated Perennial Tributaries. ....................................................................................................... 17
Table 5. Designated Uses for the La Plata River, Wetlands sustained through Hydrologic and Hydraulic
Connections and Associated Perennial Tributaries. ....................................................................................................... 17
Table 6. Designated Uses for Cherry Creek, Wetlands sustained through Hydrologic and Hydraulic
Connections and Associated Perennial Tributaries. ...................................................................................................... 18
Table 7. Designated Uses for the Piedra River, Wetlands sustained through Hydrologic and Hydraulic
Connections and Associated Perennial Tributaries. ...................................................................................................... 19
Table 8. Designated Uses for Sambrito Creek, Wetlands sustained through Hydrologic and Hydraulic
Connections and Associated Perennial Tributaries. ....................................................................................................... 19
Table 9. Designated Uses for Stollsteimer Creek Wetlands sustained through Hydrologic and Hydraulic
Connections and Associated Perennial Tributaries.......................................................................................................... 20
Table 10. Designated Uses for the San Juan River, Wetlands sustained through Hydrologic and Hydraulic
Connections and Associated Perennial Tributaries.......................................................................................................... 20
Table 11. Designated Uses for the Navajo River, Wetlands sustained through Hydrologic and Hydraulic
Connections and Associated Perennial Tributaries.......................................................................................................... 21
Table 12. Designated Uses for the Rio Blanco River, Wetlands sustained through Hydrologic and Hydraulic
Connections . ........................................................................................................................................................................... 21
Table 13. Designated Uses for Capote Reservoir and Scotts Pond. ........................................................................... 22
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Table 14. Designated Uses for Ephemeral Waters. ...................................................................................................... 22
Table 15 Aquatic Life Temperature Designations (Class 1 and 2) ................................................................................ 27
Table 16. Hardness Dependent Parameters for Calculating Freshwater Dissolved Metals Acute and Chronic
Criteria ................................................................................................................................... Error! Bookmark not defined.
Table 17. Selected Values of Calculated Acute and Chronic Criteria (µg/L). ......................................................... 28
Table 18. Equation Used for Numerical Criteria of Total Ammonia Nitrogen (“TAN”). .......................................... 29
Table 19. Selenium Numerical Criteria. ............................................................................................................................ 30
Table 20 Numeric Criteria for the Protection of Aquatic Life in Surface Water. .................................................... 31
Table 21 Numeric Criteria for the Protection of Human Health in Surface Water.................................................. 33
Table 22. These water quality requirements apply to all Outstanding Tribal Resource Waters. ........................ 41
Appendix A – Antidegradation Implementation Procedures
Appendix B – Antidegradation Review Worksheet
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WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN
UTE INDIAN RESERVATION
SOUTHERN UTE INDIAN TRIBE
E N V I RON M E N TA L P ROG R A M S D E PA R T M E N T
1 PURPOSE, AUTHORITY, AND APPLICABILITY
1.1 PURPOSE
The Southern Ute Indian Tribe (“Tribe”) adopted these water quality standards to protect public health and
welfare, enhance the quality of water, and serve the purposes of the Clean Water Act (CWA), 33 U.S.C.
Section 1251, et seq.1 These water quality standards are comprised of:
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designated uses for tribal waters;
numeric and narrative water quality criteria designed to support each designated use;
anti-degradation policies and procedures to ensure attainment and maintenance of those uses; and
general policies to protect water quality
These water quality standards serve the primary functions of establishing water quality goals for water
bodies on the Southern Ute Indian Reservation over which the Tribe has authority for purposes of setting water
quality standards and providing the legal basis for regulatory pollution controls. Establishing criteria and
designated uses that provide for protection of aquatic and wildlife species, recreational, potable water and
agricultural uses is also an important objective of these standards. More specifically, these standards are
intended to serve, and shall be implemented to achieve, the following purposes:
1. Assessment. Provide a point of reference for the assessment of surface water quality. These standards
represent the water quality goals of the Tribe for surface waters and will be used in assessing
potential impacts to that quality.
2. Regulatory Controls. Both point and nonpoint source regulatory pollution controls to be established by
the Tribe or the United States will be developed to ensure a level of water quality that will satisfy
these water quality standards. Regulatory pollution controls established for point source discharges
shall also be consistent with applicable sections of the CWA. Tribal programs to control nonpoint
sources, whether regulatory or voluntary, shall be designed to meet these water quality standards.
“Serve the purposes of the Clean Water Act” means that these water quality standards are intended, wherever
attainable, to provide water quality for the protection and propagation of fish, shellfish and wildlife and for
recreation in and on the water and take into consideration their use and value of public water supplies,
propagation of fish, shellfish, and wildlife, recreation in and on the water, and agricultural, industrial, and other
purposes including navigation.
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PURPOSE, AUTHORITY, AND APPLICABILITY
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3. Protection of Aquatic and Wildlife Species. It is the intention of the Tribe that the designated uses and
criteria assigned to tribal waters will provide a level of water quality that will be fully protective of
the aquatic and wildlife species that depend on it, including threatened or endangered species listed
under the Endangered Species Act.
1.2 AUTHORITY
Authority is both inherent to the Tribe and legally vested in the Southern Ute Indian Tribal Council by the
Constitution of the Southern Ute Indian Tribe of the Southern Ute Indian Reservation, Article VII, Section 1(n), to
protect and preserve the property, wildlife, and natural resources of the Tribe and Article VII, Section 1(e), to
protect the property, health, and general welfare of the members of the Southern Ute Indian Tribe. Under
Resolution No. 2015-16, adopted on February 17, 2015, the Southern Ute Indian Tribal Council delegated
authority to the Tribe's Environmental Programs Division (now known as Environmental Programs Department
(EPD) to exercise the Tribe’s Clean Water Act authority.
In 2018, the U.S. Environmental Protection Agency (EPA) approved the Tribe’s application for Treatment as a
State (TAS) to administer the Clean Water Act (Section 518, for purposes of the CWA Section 303(c) Water
Quality Standards) for water bodies on tribal trust land on the Southern Ute Indian Reservation (Reservation).
EPD developed Tribal Water Quality Standards (WQS) which were first adopted by the Southern Ute Indian
Tribal Council on February 8, 2022, and approved by Environmental Protection Agency (EPA) on April 15,
2022. In 2023, EPD formed its Water Quality and Remediation Division (WQRD) to administer Tribal WQS
as well as their triennial review.
The purpose of these water quality standards is to protect public health and welfare,
enhance the quality of water, and serve the purposes of the Clean Water Act.
1.3 SEVERABILITY
If any word, phrase, clause, sentence, paragraph, section, or other part of these water quality standards is
held invalid by any court of competent jurisdiction, such judgment shall affect only that portion held invalid.
1.4 APPLICABILITY
These water quality standards apply to all waters within the exterior boundary of the Southern Ute Indian
Reservation over which the Tribe has authority for establishing water quality standards (i.e., “tribal waters”).
Some of the water bodies within the exterior boundaries of the Southern Ute Indian Reservation are located
upon fee land that is owned by non-Tribal members. The Tribe has included water quality standards for all
water bodies located within the Reservation’s exterior boundaries to avoid a gap or “checkerboard” in the
standards adopted for the Reservation. The State of Colorado has claimed authority to set water quality
standards for some water bodies located within the Reservation’s exterior boundaries. This claim is disputed
by the Tribe. The Tribe intends that the standards that it is adopting apply to the water bodies in question
only to the extent that the Tribe has jurisdiction and is not attempting to resolve that jurisdictional issue here.
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1.5 CLEAN WATER ACT PROGRAM IMPLEMENTATION IN COOPERATION
WITH EPA
On March 28, 2018, the EPA determined the Tribe was eligible to be treated in the same manner as a state
under CWA Section 518(e) and 40 C.F.R. Section 131.8 for purposes of the CWA’s water quality standards
and certification programs. The Tribe anticipates that EPA will continue to exercise authority under Section
402 to issue National Pollutant Discharge Elimination System (“NPDES”) permits to facilities discharging to
tribal waters with terms consistent with these water quality standards. Any applicants for federal permits or
licenses potentially affecting tribal waters, including NPDES permits, will need to obtain a water quality
certification from the Tribe pursuant to the Tribe’s CWA Section 401 Certification Procedures. The Tribe may
also seek to enter into a Direct Implementation Tribal Cooperative Agreement with EPA under which the Tribe
will perform certain additional CWA activities (e.g., inspection of NPDES permit facilities) in cooperation with
the EPA.
1.6 INQUIRIES, CORRESPONDENCE, AND NOTIFICATIONS TO THE TRIBE
All inquiries, correspondence, and notifications to the Tribe with regard to these water quality standards are
to be directed to the Water Quality and Remediation Division Head, Environmental Programs Department
(“Department”), Southern Ute Indian Tribe, P.O. Box 737 #81, 71 Mike Frost Way, Ignacio, Colorado 81137.
Email: wqs@southernute-nsn.gov
1.7 DEFINITIONS
In this document, the terms listed below have the meanings indicated. For any terms in this document for which
a definition is not provided or for which the definition is deemed incomplete, any definitions found in the CWA
and any federal implementing regulations, guidance, or policy shall apply to the extent not inconsistent with
the intent and policies evident in this document.
Acute Toxicity is a stimulus severe enough to induce an adverse response within 96 hours of exposure or less.
Acute toxicity is not always measured in terms of lethality but may include other toxic effects that occur within
a short time period.
Antidegradation is a policy and procedure of the Tribe’s water quality standards that protects existing uses
and waters where the quality is better than necessary to support CWA Section 101 (a)(2) goal uses, as
required by federal regulations at 40 C.F.R. Section 131.12.
Assemblage is an association of aquatic organisms of similar taxonomic classification living in the same area.
Examples of assemblages include, but are not limited to fish, macroinvertebrates, algae, and vascular plants.
Aquatic Organism is any plant or animal which lives at least part of its life cycle in water.
Attainment of a goal or standard means that the water body is of sufficient quality chemically, biologically
and physically, to support the uses for which it is designated and to otherwise achieve applicable water
quality standards.
Best Management Practices (“BMPs”) are methods that have been determined to be the most effective,
practical means of preventing or reducing pollution from nonpoint sources.
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Bioaccumulative Substances are ones that increase in concentration in living organisms and/or are found to be
in higher concentrations within an organism as they move up the food chain.
Biological Condition is the taxonomic composition, richness, and functional organization of an assemblage of
aquatic organisms at a site or within a water body.
Biological Criteria, also known as biocriteria, are narrative expressions or numeric values of the biological
characteristics of aquatic communities based on appropriate reference conditions. Biological criteria are
intended to serve as an index of aquatic community health.
Chronic Toxicity is a toxicity involving a stimulus that lingers or continues for a relatively long period relative
to the life span of an organism. Chronic toxicity effects include, but are not limited to, lethality, growth
impairment, behavioral modifications, disease and reduced reproduction.
Cold Water Biota are organisms that are generally adapted to cold water environments (i.e. max
temperature of 20oC), including the expected associated diverse aquatic community, functions, and sensitive
species.
Cool Water Biota are organisms that are generally adapted to transitional zones between cold and warm
water segments (i.e., max temperature of 24oC) of a stream segment, including the expected associated
diverse aquatic community, functions, and sensitive species.
Constructed Wetlands are those wetlands intentionally designed, constructed, and operated on upland, nonwetland sites for the primary purpose of wastewater, agricultural runoff, environmental enhancement,
stormwater treatment, or environmental remediation. Constructed wetlands are not waters over which the
Tribe has authority for setting water quality standards under the CWA.
Criterion Continuous Concentration (“CCC”) is an estimate of the highest concentration of a pollutant in
freshwater, to which an aquatic community can be exposed for long periods (chronic limit) without resulting in
an unacceptable effect. The multi-day average concentration of a pollutant in ambient water should not
exceed the CCC more than once every three years on the average.
Criterion Maximum Concentration (“CMC”) is an estimate of the highest concentration of a pollutant in
freshwater, to which an aquatic community can be exposed for short periods (acute limit) without resulting in
an unacceptable effect. The one-hour average concentration in the ambient water should not exceed the CMC
more than once every three years.
Critical Condition concept is that if an effluent is controlled such that it does not cause water quality criteria to
be exceeded in the receiving water at the critical flow condition, then the effluent controls will likely be
protective (i.e., ensuring that water quality criteria are attained at all flows).
Criteria are elements of water quality standards, expressed as a desired condition, constituent concentration,
level, or narrative statement, representing a quality of water that supports a particular use.
CWA is an acronym for the Clean Water Act, 33 U.S.C. Section 1251, et seq., the common name for the
Federal Water Pollution Control Act.
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Designated Use is a use that is specified in these water quality standards as a goal for the water body
segment, whether or not it is currently being attained.
Dissolved refers to the fraction of a constituent of a water sample that passes through a 0.45 micrometer
pore-size filter. The “dissolved” fraction is also termed “filterable residue.”
Effluent is wastewater, treated or untreated, that flows out of a treatment plant, sewer, or industrial outfall.
Generally, effluent refers to wastes discharged into surface waters.
Environment is the sum of all external conditions affecting the life, development and survival of an organism.
Ephemeral Waters are water bodies that flow or contain water only in direct response to precipitation in the
immediate watershed. The stream channel of such a water body is generally above the adjacent water table.
Eutrophication is when a body of water becomes overly enriched with minerals and nutrients which can induce
excessive growth of algae. This process may result in oxygen depletion of the water body.
Existing Use is a use that is attained in the water body on or after November 28, 1975, whether or not it is
designated in the water quality standards.
Groundwater means all subsurface waters (in a zone of saturation) that are or can be brought to the surface
of the ground or to surface waters through wells, springs, seeps, or other discharge areas.
Impaired is a physical, biological or chemical condition in which a water body is not attaining the applicable
water quality standards, including the uses for which it is designated.
Intermittent Waters are water bodies that do not typically have a perennial flow or contain water perennially
and that flow or contain water in response to surface run-off and groundwater discharge.
Mixing Zones are areas surrounding or downstream of a point source discharge where the effluent plume is
progressively diluted by the receiving water and certain numerical water quality criteria otherwise applicable
to the water body segment may be exceeded.
NPDES is an acronym for National Pollutant Discharge Elimination System, the national program for issuing,
modifying, revoking and reissuing, terminating, monitoring and enforcing pretreatment requirements, under
Sections 307, 402, and 405 of the CWA.
Nonpoint Source of pollution means any source of pollutants to surface waters that is not from a single
attributable location. Nonpoint source pollution is typically associated with water moving over or through the
ground and can originate from many types of diffuse sources (e.g. agricultural, ranch and forest lands,
construction sites, development, urban runoff, atmospheric deposition, etc.).
Nutrients mean the chemical elements, primarily nitrogen and phosphorus, which are essential to the growth of
aquatic plants.
Outstanding Tribal Resource Water (“OTRW”) means a segment that has been classified as an OTRW by the
Tribe and is subject to more stringent antidegradation protection and review. OTRW segments may include,
but are not limited to, waters that have outstanding water quality, unique aquatic ecology, or recreational,
cultural, ceremonial, or aesthetic characteristics that qualify them for such classification by the Tribe.
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Perennial Waters have flowing water year-round during a typical year.
Permit means a National Pollutant Discharge Elimination System permit or other tribal or federal water quality
permit.
pH is a measure of hydrogen ion concentration, a measure of the acidity or alkalinity of a solution.
Point Source is any discernible, confined and discrete conveyance including, but not limited to, any pipe, ditch,
channel, sewer, tunnel, conduit, well, discrete fissure, container, concentrated animal feeding operation, or
vessel or other floating craft, from which pollutants are or may be discharged.
Pollutant includes, but is not limited to dredged soil, solid waste, incinerator residue, filter backwash, sewage,
garbage, sewage sludge, munitions, chemical wastes, biological materials, radioactive materials (except those
regulated under the Atomic Energy Act of 1954 as amended, 42 U.S.C. Section 2011, et seq.), heat, wrecked
or discarded equipment, oil, mine tailings, rock, sand, cellar dirt and industrial, municipal, and agricultural
waste discharged into water.
Pollution includes such contamination, or other alteration of the physical, chemical, or biological properties of
any waters of the tribe, including change in temperature, taste, color, turbidity, or odor of the waters, or such
discharge of any liquid, gaseous, solid, radioactive, or other substance, or any exotic biota into any waters of
the Tribe that will or is likely to create a nuisance to or impair any beneficial use of such waters.
Receiving Water is any water course or water body that receives a treated or untreated discharge of a
pollutant or pollution from a point source or nonpoint source.
Regulated Activity is any activity that requires a permit or a water quality certification pursuant to CWA
Section 401 or any other federal law (e.g., without limitation, Section 402 NPDES permits, Section 404
dredge and fill permits, and Federal Energy Regulatory Commission licenses) and any other activities where
tribal law or regulation specifies that an antidegradation review is required.
Summer is the period from April 15th to October 14th as it relates to temperature classifications (Section 8.5).
Total Recoverable Metals is that portion of a water and suspended sediment sample measured by the total
recoverable analytical procedure described in “Methods for Chemical Analysis of Water and Wastes,” U.S.
Environmental Protection Agency, March 1979, or its equivalent.
Toxics are those pollutants that have a harmful effect on living organisms. The CWA Section 307(a) priority
toxic pollutants are a subset of this group of pollutants.
Toxicity is the degree to which a chemical substance or pollutant can be harmful or cause damage to an
organism. Toxicity is typically expressed as either acute or chronic toxicity.
Tribal Waters are waters over which the Tribe has authority for establishing water quality standards.
Tribe refers to the Southern Ute Indian Tribe.
Use Attainability Analysis (“UAA”) is a structured scientific assessment of the factors affecting the attainment
of aquatic life uses or other designated uses, which may include physical, chemical, biological, and economic
factors.
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Warm Water Biota are organisms that are generally adapted to warm water environments (i.e. max
temperature of 30oC), including the expected associated diverse aquatic community, functions, and sensitive
species.
Water Quality Standards (“WQS” or “Standards”) consist of a designated use or uses, numeric and narrative
criteria, an antidegradation policy, and other policies adopted to protect, maintain, and enhance water
quality.
Wetlands are those areas that are inundated or saturated by surface or groundwater at a frequency and
duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation
typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs and
similar areas.
Winter is the period from October 15th to April 14th as it relates to temperature classifications (Section 8.5).
2 IMPLEMENTATION OF STANDARDS
All discharges from point sources, all instream activities, and all activities that generate nonpoint source
pollution are to be conducted so as to achieve these water quality standards. The Tribe anticipates that both
regulatory and voluntary pollution control programs will be needed to protect and enhance water quality on
the Reservation.
All activities which require a federal license or permit on the Reservation are subject to certification by the
Tribe consistent with CWA Section 401 (see “Southern Ute Indian Tribe CWA Section 401 Certification
Procedures”). All federal licenses and permits, such as permit for wastewater discharges issued under the
NPDES, should be conditioned in such a manner as to authorize only activities that will not cause violations of
these water quality standards. For new standards, revised standards that have become more stringent, or new
interpretations of existing standards, the Tribe has the authority to allow schedules of compliance which may
be included in such permits, where appropriate, considering guidance issued by EPA. Schedules of compliance
may be authorized by the Tribe on a case-by-case basis.
Unless the Tribe receives eligibility to implement CWA Section 402, discharge permits for discharges to tribal
waters will be issued by the EPA. All discharge permit applications will be reviewed by the Tribe pursuant to
its Section 401 certification authority. In accordance with the Tribe’s antidegradation review procedures, the
Tribe may deny certification of any discharge into tribal waters, if the Tribe determines that the proposed
discharge would cause a violation of these water quality standards.
These water quality standards should serve as a basis for the Tribe's (or EPA's, as applicable) review of
proposed discharges from upstream sources under the Clean Water Act Section 401 water quality
certification process. This review will ensure that any proposed upstream discharge, regardless of its origin, is
consistent with the Tribe's established water quality goals and objectives as outlined in these standards.
The Tribe retains the authority to specify, within a water quality certification, particular methods for
implementing water quality standards when establishing pollution control measures for both point and
nonpoint sources. All controls shall be developed using technically defensible methods such as those described
in EPA guidance documents.
IMPLEMENTATION OF STANDARDS
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These water quality standards should serve as the basis for any Section 303(d) total maximum daily loads
(TMDLs) developed for tribal waters. These water quality standards apply to all Tribal waters affected by
point sources of pollution. For nonpoint sources of pollution, the primary means for implementing the standards
shall be through the application of all known and reasonable methods of prevention, control, and treatment,
including BMPs, which shall be required in water quality certifications issued by the Tribe. At this time, the
Tribe intends to rely on voluntary compliance for activities which result in nonpoint sources of pollution but are
not regulated activities.
2.1 CRITICAL CONDITIONS
For purposes of determining water quality-based control requirements for point source discharges, critical
conditions shall be determined consistent with the policy and procedure described below where a steady
state modeling approach is used. Where seasonal controls are appropriate, critical conditions shall be
determined based on seasonal characteristics of the receiving water and pollution source. Other exceptions
may be granted where a technically sound reason to use an alternative method is developed and approved
by the Tribe (e.g., where a dynamic or continuous simulation modeling method is used). Critical conditions shall
be representative of conditions upstream from the point where the discharge exists.
The following critical flows may be assumed to dilute the effluent:
Stream Flows
Chronic Aquatic Life
4-day, 3-year flow (biologically based)
Acute Aquatic Life
1-day, 3-year flow (biologically based)
Human Health (carcinogens)
harmonic mean flow
Human Health (non- carcinogens)
4-day, 3-year flow (biologically based),
or 1-day, 3-year flow (biologically based)
Effluent Flows
Chronic Aquatic Life
Mean daily flow
Acute Aquatic Life
Maximum daily flow
Human Health (all)
Mean daily flow
Assessment of attainment of designated uses and compliance with water quality criteria shall be in
accordance with available guidance and procedures published by EPA.
2.2 WATER RIGHTS
Implementation of these water quality standards shall not interfere with the lawful diversion of water pursuant
to decreed water rights. However, the Tribe encourages individuals and entities to manage and administer
water diversions in a manner that supports the attainment and enhancement of designated uses whenever
practicable.
3 TRIENNIAL REVIEW
The Tribe shall hold a hearing to review these water quality standards at least once every three years for the
purpose of determining whether revisions are necessary or warranted to comply with applicable federal
TRIENNIAL REVIEW
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regulations or to meet tribal water quality goals. For example, any water body segment with designated uses
that do not include the goal uses specified in CWA Section 101(a)(2) shall be re-examined every three years
to determine if any new information has become available. If such new information indicates the CWA goal
uses are attainable, the Tribe shall revise its standards accordingly.
The procedures for a triennial review or any other revisions to these water quality standards shall meet the
requirements of CWA Section 303(c) and tribal administrative procedures. Public hearings shall be held in
accordance with tribal laws and EPA requirements. Any proposed water quality standards revisions and
supporting analyses shall be made available to the public before the hearing. The Tribe shall submit the
revised standards and any supporting analyses to the EPA Region 8 Regional Administrator for review and
approval within 30 days following the final action to adopt revised standards. The Tribe’s submission shall be
consistent with EPA requirements found in 40 C.F.R. Section 131.6.
4 MIXING ZONES AND DILUTION POLICY
4.1 PURPOSE
Mixing zones are regions surrounding or downstream of a point source discharge in which the discharge is
progressively diluted by the receiving water and some numerical water quality criteria may not apply. This
policy establishes how mixing and dilution of point source discharges with receiving waters will be addressed
in developing chemical-specific and whole effluent toxicity discharge limitations. Depending on site-specific
mixing patterns and environmental concerns, some pollutants may be allowed a mixing zone for dilution and
others may not. In all cases, mixing zone and dilution allowances shall be limited as necessary to protect
designated uses and the integrity of the receiving water ecosystem as a whole. This policy shall be
implemented consistent with the most recent EPA guidance and procedures.
4.2 IMPLEMENTATION
Where dilution is available at critical conditions and the discharge does not completely mix at a near
instantaneous rate, on a case-by-case basis an appropriate mixing zone may be designated if:
1. meeting numeric criteria at the end-of-pipe is not practicable;
2. allowing a mixing zone will not pose unacceptable risks to designated uses in the receiving water as a
whole, considering factors such as:
a. bioaccumulation in fish tissues or wildlife;
b. biologically important areas such as fish spawning or nursery areas;
c. presence of listed or proposed threatened or endangered species or of species of concern;
d. low acute to chronic ratio;
e. potential human exposure to pollutants via drinking water or recreational activities;
f. attraction of aquatic species to effluent plume;
g. toxicity or persistence of the substance discharged;
h. zone of passage for migrating fish or other species (including access to tributaries); and
i. cumulative effects of multiple discharges and mixing zones.
3. narrative criteria will be achieved within the mixing zone.
Effluent limits will be assigned consistent with mixing zone size limits determined by field study, an
appropriate mixing model, or other defensible method. Mixing zone size shall generally be limited as follows,
MIXING ZONES AND DILUTION POLICY
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WATER QUALITY STANDARDS
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provided that individual chronic mixing zones may be further limited or denied as needed to protect
designated and existing uses based on the factors listed above:
1. No acute mixing zone shall be allowed;
2. The size of chronic mixing zones for streams and rivers shall not exceed one-half the cross-sectional
area or a length 10 times the stream width at critical low flow, whichever is more limiting; and
3. Each mixing zone will be developed on a case-by-case basis to protect the most sensitive designated
use, consistent with applicable EPA guidance.
Where the discharge is to a river or stream, dilution is available at critical conditions, and available
information is sufficient to reasonably conclude that the discharge exhibits near instantaneous and complete
mixing, an appropriate dilution allowance equal to or less than the critical low flows identified in Section 3
may be provided for purposes of establishing acute and chronic chemical-specific and whole effluent toxicity
effluent limitations. Near instantaneous and complete mixing may be assumed where the mean daily flow of
the discharge exceeds the critical low flow of the receiving water, or where an effluent diffuser has been
installed. In all other cases where instantaneous and complete mixing is assumed, a defensible basis should be
included in the statement of basis for the permit. For purposes of field mixing studies, near instantaneous and
complete mixing is defined as no more than 10% difference in bank-to-bank concentrations within a
longitudinal distance not greater than two stream widths. Where dilution flow is not available at critical
conditions, the discharge limits will be based on achieving water quality criteria at the end-of-pipe. In
addition, discharge limits for all point source discharges to a wetland will be based on achieving water
quality criteria at the end-of-pipe.
All mixing zone-dilution assumptions are subject to review and revision as information on the nature and
impacts of the discharge becomes available (e.g., chemical or biological monitoring in the mixing zone
boundary). At a minimum, mixing zone and dilution decisions are subject to review and revision along with all
other aspects of the discharge permit upon expiration of the permit. Where warranted, the discharger may
be required to complete monitoring to verify that mixing zone restrictions are being achieved. For certain
pollutants (e.g., ammonia, dissolved oxygen, metals, etc.) that may exhibit increased toxicity or other effects
on water quality after dilution and complete mixing with receiving waters is achieved, permit terms should
address such toxicity or other effects on water quality as necessary to fully protect designated uses (i.e., the
point of compliance may be something other than the mixing zone boundary or the point where complete
mixing is achieved).
5 DESIGNATED USES
40 C.F.R. Section 131.10 requires that the Tribe specify appropriate water uses to be achieved and
protected. The designation of uses for tribal waters must take into consideration the use and value of water
for public water supplies, protection and propagation of fish, shellfish and wildlife, recreation in and on the
water, agricultural, industrial, and other purposes including navigation. In no case can waste transport or
waste assimilation be adopted as a designated use. In designating uses and the appropriate criteria for those
uses, the Tribe must take into consideration the water quality classifications and standards of downstream
waters and ensure that as implemented through its policies, the water quality classifications and standards of
downstream waters will be attained and maintained.
The Tribe has elected to consider the following designated uses for tribal waters.
DESIGNATED USES
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WATER QUALITY STANDARDS
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5.1 DESIGNATED USE CODES
Table 1. Designated Use Codes
CODE
COLD1
COLD2
COOL1
COOL2
WARM1
WARM2
REC1
REC2
PWS
IND
AGR
USE
High Quality Cold Water Aquatic Life (Class 1)
Low Quality Cold Water Aquatic Life (Class 2)
High Quality Cool Water Aquatic Life (Class 1)
Low Quality Cool Water Aquatic Life (Class 2)
High Quality Warm Water Aquatic Life (Class 1)
Low Quality Warm Water Aquatic Life (Class 2)
Primary Contact Recreation (Class 1)
Secondary Contact Recreation (Class 2)
Potable Water Supply
Industrial Water Supply
Agricultural Water Supply
5.2 DESIGNATED USES DEFINITIONS
The following designated uses may be applied to tribal waters:
Potable Water Supply - Waters suitable or intended to become suitable, after appropriate pretreatment, for
human consumption.
Primary Contact Recreation (Class 1) – Waters suitable for recreational activities where full body immersion
and/or the ingestion of small quantities of water is likely to occur. Such activities include but are not limited to
swimming, rafting, kayaking, tubing, windsurfing, water-skiing, and water play by children.
Secondary Contact Recreation (Class 2) – Water suitable for recreational activities where a person’s water
contact is likely to be limited (e.g., wading or fishing) such that exposure of the eyes, ears, respiratory, or
digestive systems or urogenital areas would normally be avoided.
Aquatic Life (Class 1) – High quality waters that support or are intended to become supportive of a typical
diversity and abundance of cold, cool, or warm water aquatic biota that are generally able to function at
intermediate or transitional zones between temperatures representative of a stream segment, including the
expected diverse aquatic community, functions, and sensitive species.
Aquatic Life (Class 2) – Low quality waters that are not capable of sustaining a typical diversity or
abundance of cold, cool, or warm water aquatic biota, respectively, due to physical habitat, water flows or
levels, or uncorrectable water quality conditions that result in substantially limited abundance or diversity of
species.
Industrial Water Supply - Waters that are suitable for industrial processes and cooling water.
Agricultural Water Supply - Waters suitable or intended to become suitable for irrigating crops and for use
as drinking water for livestock.
DESIGNATED USES
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5.3 STREAM SEGMENTATION CRITERIA
For purposes of adopting designated uses and water quality criteria, streams and other surface water bodies
were identified according to river basin or sub-basin and specific segments.
Segments may constitute a specific reach of a stream mainstem, a specific tributary, a specific lake or
reservoir, or a generally defined grouping of waters within a basin (e.g., a specific mainstem segment and
another segment consisting of all tributaries flowing into that mainstem segment).
Segments were delineated to create consistency in the designation of uses by determining segment
boundaries according to where physical or water quality characteristics of a watercourse change significantly
enough to require a change in use classifications or water quality criteria. In many cases, boundaries between
segments were identified directly using water quality data. In other cases, data were only available upstream
or downstream of a segment boundary and the delineation of segments was inferred using best professional
judgment of where instream changes in uses, physical characteristics, or water quality occur.
The Tribe’s adopted water quality standards define wetlands as “…those areas that are inundated or
saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal
circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions.”
Section 5.8 of the Tribe’s water quality standards state: “Intermittent and ephemeral waters shall support
existing and designated uses when there is surface water present from any source, however minimal. The
numeric and narrative criteria for connected perennial segments shall apply to intermittent and ephemeral
water bodies when there is surface water present from any source, however minimal.”
Water aggregates within and discharges from wetland areas as part of the hydrologic cycle on time scales
that are perennial, intermittent, or ephemeral in nature. The waters that sustain wetlands connect (i.e., make
physical contact with or contribute in quantity or quality) to other bodies of surface water that are relatively
permanent, standing or continuously flowing - regardless of the degree to which that hydrologic or hydraulic
connection is navigable.
The Tribe’s water quality standards therefore define “wetlands sustained through hydrologic and hydraulic
connections” as any areas that:
1. Are inundated or saturated by surface or groundwater at a frequency and duration sufficient to
support, and that under normal circumstances do support, a prevalence (i.e., 50% cover or greater, as
estimated within 1 square meter (1 m2) of land area) of vegetation typically adapted for life in
saturated soil conditions, and
2. Contain a prevalence of the aforementioned vegetation that encompasses 1/10 (.10%) of an acre or
greater in area, regardless of its degree of physical proximity, adjacency, and surface connection (or
lack thereof) to navigable or non-navigable waterways.
5.4 ASSIGNING DESIGNATED USES
Designated uses for tribal waters have been assigned by the Tribe in accordance with Sections 101(a)(2) and
303 of the CWA and the implementing federal regulation at 40 C.F.R. Section 131.10. All segments have
been assigned the highest attainable uses that the Tribe reasonably believes the segment can support. The
DESIGNATED USES
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WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
designated uses may be revised for a segment as part of the triennial review process or if new information or
data indicates that a revision is warranted, subject to the policies and limitations discussed below.
Section 101(a) (2) requires that waters be designated as “fishable and swimmable” (i.e., supporting
protection and propagation of fish, shellfish, and wildlife, and providing for recreation in and on the water)
unless a use attainability analysis (UAA) demonstrates that a less stringent use designation is appropriate.
Accordingly, those waters that do not fully support, and it is believed cannot reasonably support, fishable and
swimmable uses must be evaluated in a UAA to determine their potential and possible downgraded uses. On
the other hand, some uses may be designated that are not currently attained, but for which there is a
reasonable expectation that those uses can be attained using point and nonpoint source controls of pollutants.
The following specific policies and limitations apply to assigning and revising designated uses for tribal
waters:
1. The Tribe will not remove a designated use specified in CWA Section 101(a)(2) (i.e., “fishable and
swimmable” uses) or adopt subcategories of a Section 101(a)(2) use requiring less stringent criteria
unless a UAA demonstrates that attaining the use is not feasible because of a factor listed in 40 C.F.R.
Section 131.10(g).
2. An existing designated use for a segment will not be removed unless a use requiring more stringent
criteria is designated.
3. Assigning designated uses will be guided by the objective of realizing the water quality goals set
forth in the CWA.
4. Designated uses must be protective of water quality for all current and future uses consistent with the
Tribe’s Antidegradation Policy.
5. Designated uses will be set for the highest water quality reasonably attainable. Attainability is to be
judged through preparing a UAA and whether the use designation can be attained in a timeframe
approximating twenty years by reasonable control techniques that are determined during public
hearing. At a minimum, uses are deemed attainable if they can be achieved by the imposition of
effluent limits required under the CWA for point sources and cost-effective and reasonable best
management practices for nonpoint source control.
6. Designated uses set for upstream segments should not jeopardize attainable downstream designated
uses.
7. Relevant physical, chemical, and biological characteristics are valid water quality concerns that may
be taken into account in the use designation process.
5.5 USE ATTAINABILITY ANALYSES
A UAA is a structured scientific assessment completed to evaluate the factors affecting the attainability of a
use. Whenever a UAA is prepared, it shall be subject to the requirements and limitations set forth in 40 C.F.R.
Part 131, including subsections 131.3(g), 131.10(g), 131.10(h) and 131.10(j). The Tribe completed UAAs to
support its initial use designations for certain segments. All UAAs, Aquatic Life UAAs and/or Recreation UAAs,
shall be revised and supplemented as new information and data become available.
In addition to the Tribe, third parties may petition for and complete a UAA to support a proposed revision to
the designated uses for one or more segments. The petitioner shall submit notice to the Tribe stating its intent
to conduct a UAA for tribal waters. The petitioner shall develop a work plan to conduct the UAA and shall
submit the work plan to the Tribe for review and comment. The work plan shall identify the scope of data
DESIGNATED USES
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WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
currently available and the scope of data to be gathered, the factors affecting use attainment that will be
analyzed, and provisions for public notice and consultation with appropriate tribal and federal agencies. The
Tribe may consult with EPA in its review of the work plan. Upon approval of the work plan by the Tribe, and
subject to any required amendments thereto, the petitioner shall conduct the UAA in accordance with the
approved work plan. All costs of such analysis shall be the responsibility of the petitioner. Upon completion of
the UAA, the petitioner shall submit the data, findings, conclusions, and proposed use revision(s) to the Tribe.
Proposed third party use revisions will be evaluated by the Tribe, and may be proposed to the public during
the next water quality standards rulemaking opportunity. Revisions to designated uses are final only after
adoption by the Tribe and CWA review and approval by EPA.
5.6 CHANGING USE DESIGNATIONS
The Tribe may assign a new designated use or change a currently designated use based upon the
requirements in this document, public testimony, and any other information considered at a public hearing
concerning the proposed change. Any interested person shall have the right to petition the Tribe to assign or
change a use designation. Action on such petition shall be within the discretion of the Tribe subject to the
following policies:
1. Adding Designations – The Tribe shall maintain those water quality use designations which are
currently being attained. Where current designations specify fewer designated water uses than those
which are presently being attained, the Tribe will add the designated use(s) to reflect the uses
actually being attained or for which there is a reasonable expectation that those uses can be
attained.
2. Removing or Reducing Designations – If the Tribe or a petitioning party can scientifically demonstrate
that a designated use is not being attained; that the designated use cannot reasonably be attained
due to a factor listed in 40 C.F.R. Section 131.10(g); and the use is not an existing use; then the
designation may be downgraded (e.g., from “High Quality Class 1” to “Low Quality Class 2”) or
removed by the Tribe. When a petitioner wishes to remove or downgrade an aquatic life or
recreation classification or recommends adopting a less stringent criterion for a water body
designated for these uses, the Tribe shall require the petitioner to conduct a UAA to justify the
proposed change. Where changing circumstances, such as improvements in technology or management
practices or the cessation of a discharge, may allow the reasonable attainment of the current uses
within a reasonable time, the Tribe shall instead favor granting a variance as provided in Section 14
and maintaining the current uses as a goal.
3. Where the use designations of a water body segment include a use designation with less stringent
criteria, or do not include an aquatic life and/or recreation class 1 designation, as part of the triennial
review of the segment, the Tribe shall review any prior UAA or other basis for omission of one or more
of the above designated uses. If the justification for the omission is determined not to be consistent
with current data and information or accepted use attainability policies, the Tribe shall perform a
supplemental analysis to provide a basis for a determination by the Tribe whether such uses are
attainable.
5.7 SURFACE WATER USE DESIGNATIONS FOR TRIBAL WATERS
Use designations adopted for all surface water segments, tributaries and lakes that are tribal waters are
listed in the following tables. In cases where the upper end of a stream segment is defined by a tributary, that
DESIGNATED USES
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WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
tributary is included in that segment unless specified otherwise. Latitude and longitude coordinates (WGS
1984) are provided for segment boundaries.
All Segments on the Reservation are designated Seasonal COLD1 in the Winter: October 15- April 15.
Temperature designations for Summer: April 16- October 14 are identified in the tables below.
Table 2. Designated Uses for the Pine River, Wetlands sustained through Hydrologic and Hydraulic Connections and
Associated Perennial Tributaries.
Segment and Description
Pine River Segment1
(Reservation boundary to Pine Ditch
Diversion and all perennial streams,
small ponds and wetlands tributary
to this segment)
Pine River Segment2
(Pine Ditch Diversion to confluence
with Dry Creek and all perennial
streams, small ponds and wetlands
tributary to this segment, excluding
Dry Creek,)
Pine River Segment3
(Dry Creek to New Mexico state
line, including Dry Creek, and all
perennial streams, small ponds and
wetlands tributary to this segment)
DESIGNATED USES
Designated Uses
Segment Boundaries
COOL1
REC1
PWS
AGR
Northern Boundary Pine Ditch Diversion
River Mile 19.5
River Mile 17.5
N 37.214814
N 37.190642
W -107.595264
W -107.587775
COOL1
REC1
PWS
AGR
Pine Ditch Diversion Dry Creek Confluence
River Mile 17.5
River Mile 12
N 37.190642
N 37.139717
W -107.587775
W -107.620411
WARM1
REC1
PWS
AGR
Dry Creek
Confluence
River Mile 12
N 37.139717
W -107.620411
Southern Boundary
River Mile 0
N 36.999978
W -107.601111
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WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
Table 3. Designated Uses for the Animas River, Wetlands sustained through Hydrologic and Hydraulic Connections
and Associated Perennial Tributaries.
Segment and
Description
Designated
Uses
Animas River Segment1
COOL1
REC1
PWS
AGR
Northern Boundary Basin Creek
River Mile 19
River Mile 15
N 37.214794
N 37.18606944
W -107.854722
W --107.878889
COOL1
REC1
PWS
AGR
Basin Creek
River Mile 15
N 37.18606944
W -107.878889
Florida River
River Mile 3.8
N 37.048706
W -107.872933
COOL1
REC1
PWS
AGR
Florida River
River Mile 3.8
W 107.872933
N 37.048706
Southern Boundary
River Mile 0
N 36.999739
W -107.866181
(Reservation boundary to
Basin Creek and all
perennial streams, small
ponds and wetlands
tributary to this segment,
excluding Basin Creek,)
Animas River Segment2
(Basin Creek to confluence
with Florida River, excluding
the Florida River including
Basin Creek, and all
perennial streams, small
ponds and wetlands
tributary to this segment,
excluding the Florida River)
Animas River Segment3
(Florida River to New Mexico
state line and all perennial
streams (excluding the
Florida River), small ponds
and wetlands tributary to
this segment)
DESIGNATED USES
Segment Boundaries
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WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
Table 4. Designated Uses for the Florida River, Wetlands sustained through Hydrologic and Hydraulic Connections and
Associated Perennial Tributaries.
Segment and
Description
Designated
Uses
Florida River
(Reservation boundary to
Animas River and all
perennial streams, small
ponds and wetlands
tributary to this segment)
WARM1
REC1
PWS
AGR
Segment Boundaries
Northern Boundary
River Mile 22.9
N 37.21497222
W -107.72916667
Confluence with
Animas
River Mile 0
N 37.048706
W -107.872933
Table 5. Designated Uses for the La Plata River, Wetlands sustained through Hydrologic and Hydraulic Connections
and Associated Perennial Tributaries.
Segment and
Description
Designated
Uses
La Plata River
Segment1
(Northern Reservation
boundary to the
confluence of Cherry
Creek and all
perennial streams,
small ponds and
wetlands tributary to
this segment, excluding
Cherry Creek,)
La Plata River
Segment2
(Cherry Creek to
Long Hollow Creek
and all perennial
streams, small ponds
and wetlands
tributary to this
segment, excluding
Segment Boundaries
COOL1
REC2
PWS
AGR
Northern Boundary
River Mile 21.4
N 37.214814
W -108.061594
Cherry Creek
River Mile 9.7
N 37.11562778
W -108.198333
WARM1
REC2
PWS
AGR
Cherry Creek
River Mile 9.7
N 37.11562778
W -108.198333
Long Hollow Confluence
River Mile 4.4
N 37.05325
W -108.182108
DESIGNATED USES
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WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
Long Hollow and
Cherry Creek)
La Plata River
Segment3
(Long Hollow Creek
to southern end of the
Reservation, including
Long Hollow Creek,
and all perennial
streams, small ponds
and wetlands
tributary to this
segment)
COOL1
REC2
PWS
AGR
Long Hollow Confluence
River Mile 4.4
N 37.05325
W -108.182108
Southern Boundary
River Mile 0
N 36.999719
W -108.188558
Table 6. Designated Uses for Cherry Creek, Wetlands sustained through Hydrologic and Hydraulic Connections and
Associated Perennial Tributaries.
Segment and Description
Designated
Uses
Cherry Creek
WARM1
REC2
PWS
AGR
(Northern Reservation boundary
to the confluence of the La Plata
River and all perennial streams,
small ponds and wetlands
tributary to this segment)
DESIGNATED USES
Segment Boundaries
Northern Boundary
River Mile 7.9
N 37.215056
W -108.223667
Confluence with the
La Plata River
River Mile 10.2
N 37.115661
W -108.198542
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WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
Table 7. Designated Uses for the Piedra River, Wetlands sustained through Hydrologic and Hydraulic Connections
and Associated Perennial Tributaries.
Segment Description
Piedra River Segment1
Designated
Uses
Segment Boundaries
COOL1
REC1
PWS
AGR
Northern Boundary
River Mile 15.8
N 37.214789
W -107.348381
Confluence with Stollsteimer
Creek
River Mile 5.3
N 37.1388361
W -107.355000
Piedra River Segment2
WARM1
(Confluence with
Stollsteimer Creek to
Navajo Reservoir and
all perennial streams,
small ponds and
wetlands tributary to
this segment, excluding
Stollsteimer Creek)
REC1
PWS
AGR
Confluence with Stollsteimer
Creek
River Mile 5.3
N 37.1388361
W -107.355000
High Water Elevation of
Navajo Reservoir
River Mile 0
N 37.054994
W -107.410683
(Reservation boundary
to confluence with
Stollsteimer Creek and
all perennial streams,
small ponds and
wetlands tributary to
this segment, excluding
Stollsteimer Creek)
Table 8. Designated Uses for Sambrito Creek, Wetlands sustained through Hydrologic and Hydraulic Connections and
Associated Perennial Tributaries.
Segment and Description
Sambrito Creek
(Headwaters to confluence
with Navajo Reservoir and
all perennial streams, small
ponds and wetlands
tributary to this segment)
DESIGNATED USES
Designated
Uses
WARM1
REC1
PWS
AGR
Segment Boundaries
Headwaters
River Mile 12
N 37.139181
W -107.464247
Confluence with Navajo
Reservoir
River Mile 0
N 37.006569
W -107.457364
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WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
Table 9. Designated Uses for Stollsteimer Creek Wetlands sustained through Hydrologic and Hydraulic Connections
and Associated Perennial Tributaries.
Segment and
Description
Stollsteimer Creek
(Reservation boundary to
confluence with Piedra River
and all perennial streams,
small ponds and wetlands
tributary to this segment)
Designated
Uses
WARM1
REC1
PWS
AGR
Segment Boundaries
Reservation
Boundary
River Mile 14.2
N 37.21484167
W -107.220278
Confluence with Piedra
River
River Mile 0
N 37.138947
W -107.355278
Table 10. Designated Uses for the San Juan River, Wetlands sustained through Hydrologic and Hydraulic Connections
and Associated Perennial Tributaries.
Segment
San Juan River Segment1
(Northern Reservation
boundary to Rio Blanco and
all perennial streams, small
ponds and wetlands tributary
to this segment, excluding Rio
Blanco)
San Juan River Segment2
Rio Blanco to confluence with
Navajo River and all
perennial streams, small
ponds and wetlands tributary
to this segment, excluding Rio
Blanco and Navajo River)
San Juan River Segment3
(Confluence with Navajo
River to Navajo Reservoir
and all perennial streams,
small ponds and wetlands
DESIGNATED USES
Designated
Uses
Segment Description and Location
WARM1
REC1
PWS
AGR
Northern Boundary
River Mile 36.1
N 37.218325
W -107.018056
Confluence with Rio
Blanco
River Mile 28.4
N 37.120727
W -107.043497
WARM1
REC1
PWS
AGR
Confluence with Rio
Blanco
River Mile 28.4
N 37.120727
W -107.043497
Confluence with
Navajo River
River Mile 15.1
N 37.024364
W -107.158656
WARM1
REC1
PWS
AGR
Confluence with
Navajo River
River Mile 15.1
N 37.024364
W -107.158656
Navajo Reservoir
River Mile 0
N 37.019003
W -107.344558
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WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
tributary to this segment,
excluding Navajo River)
Table 11. Designated Uses for the Navajo River, Wetlands sustained through Hydrologic and Hydraulic Connections
and Associated Perennial Tributaries.
Segment
Navajo River
(Southern Boundary to
confluence with the San Juan
River and all perennial
streams, small ponds and
wetlands tributary to this
segment)
Designated
Uses
WARM1
REC1
PWS
AGR
Segment Description and Location
Reservation
Boundary
River Mile 4.7
N 37.000069
W -107.108752
Confluence with San
Juan River
River Mile 0
N 37.024364
W -107.158656
Table 12. Designated Uses for the Rio Blanco River, Wetlands sustained through Hydrologic and Hydraulic
Connections.
Designated
Uses
Segment
Rio Blanco River
(Southern Boundary to
confluence with the San Juan
River and all perennial
streams, small ponds and
wetlands tributary to this
segment)
DESIGNATED USES
WARM1
REC1
PWS
AGR
Segment Description and Location
Reservation
Boundary
River Mile 3.2
N 37.135
W -107.001
Confluence with San
Juan River
River Mile 0.0
N 37.120727
W -107.043497
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WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
Table 13. Designated Uses for Capote Reservoir and Scotts Pond.
Water body
Capote Reservoir
Scott’s Pond
Designated Uses
Location
WARM1
REC1
WARM1
REC1
N 37.199403
W -107.257744
N 37.135747
W -107.623406
Table 14. Designated Uses for Ephemeral Waters.
Segment
All Ephemeral Waters
Designated Uses
WARM1
REC2
AGR
PWS
Segment Description and
Location
Reservation wide
5.8 INTERMITTENT AND EPHEMERAL WATERS
Intermittent and ephemeral waters shall support existing and designated uses when there is surface water
present from any source, however minimal. The numeric and narrative criteria for connected perennial
segments shall apply to intermittent and ephemeral water bodies when there is surface water present from
any source, however minimal.
5.9 TRIBAL WATERS SUBJECT TO USE ATTAINABILITY ANALYSES
CWA Section 101(a)(2) requires that waters be designated as “fishable and swimmable” (supporting
protection and propagation of fish, shellfish, and wildlife, and providing for recreation in and on the water)
unless a Use Attainment Analysis (UAA) demonstrates that a less stringent use designation and criteria are
appropriate. The segments listed below have Secondary Contact Recreation (Rec 2 or Class 2) use
designations. These waters are protected by Primary Contact Recreation (Rec 1 or Class 1) criteria (see
section 8.4 below) so do not require supporting UAAs. A UAA will be prepared for each segment that does
not fully support a Class 1 Aquatic Life or Class 1 Recreation use designation and is assigned criteria less
stringent than Class 1.
•
•
•
La Plata River Segments 1, 2 and 3, Recreation only
Cherry Creek, Recreation only
All Ephemeral Waters, Recreation only
6 NARRATIVE WATER QUALITY CRITERIA
All tribal waters are subject to the narrative water quality criteria below. The goal of the narrative water
quality criteria is to be able to assess and protect water quality using parameters that humans and biota can
directly perceive and in situations where numeric standards for individual pollutants or parameters may not
be sufficient.
NARRATIVE WATER QUALITY CRITERIA
Page 22
WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
6.1 CRITERIA
Surface waters shall be free from substances attributable to human-caused point or nonpoint sources in
amounts, concentrations, or combinations which may:
1. settle to form deposits beneath the water surface or upon adjoining shorelines that have a deleterious
effect on biota or that significantly alter the physical or chemical properties of the water or the
bottom sediments;
2. form objectionable floating debris, scum, film, grease, oil, or other surface materials, including
“floatable material” as defined by the CWA;
3. produce color, turbidity, odor, or other conditions in such a degree as to impair photosynthesis, reduce
water clarity, or create a nuisance;
4. cause eutrophication resulting in the objectionable growth of aquatic vegetation or algae or other
impairments from excessive nutrients to the extent that it threatens public health or welfare or impairs
present or future beneficial uses.
5. impart any undesirable taste to edible aquatic or terrestrial species or to the water;
6. cause injury to or are toxic to humans or aquatic or terrestrial animals or plants;
7. produce undesirable or nuisance aquatic or terrestrial animals or plants; or
8. impair the capability of a water body to support a designated use.
6.2 IMPLEMENTATION
The narrative water quality criteria shall be implemented taking into consideration appropriate EPA technical
guidance concerning the development of water quality-based controls. To implement these criteria for
substances that lack numeric criteria for public water supply use, drinking water standards or health advisories
issued by EPA under the Safe Drinking Water Act will be considered. For point source discharges, criteria
6.1(5) and (6) should be implemented by including appropriate acute and chronic chemical-specific and
Whole Effluent Toxicity effluent quality limitations in the NPDES permit, as specified in the latest EPA NPDES
Whole Effluent Toxicity Program guidance. For substances that lack numeric water quality criteria or for which
numeric criteria are not protective or representative of water quality goals, these narrative water quality
criteria shall be implemented considering appropriate information, including any criteria guidance issued by
EPA under CWA Section 304(a) or information in EPA or other toxicity databases, and the Tribe’s best
professional judgement.
Although the Tribe does not envision that it will always be necessary to establish effluent limits for point source
discharges based on narrative criteria, the Tribe intends that the narrative criteria are to be used as required
by CWA Section 301(b)(1)(C) and 40 C.F.R. Section 122.44(d) in determining appropriate effluent limits for
point source discharges. For example, where the narrative criteria are not attained, that information can be
used by the permitting authority to reevaluate any NPDES permits for upstream discharges to determine if all
appropriate chemical-specific and whole effluent toxicity limits are included in the permits. This may involve
examining whether such permits contain limits for all substances present in the discharge and for any pollutants
or parameters that are or may be discharged that cause, have the reasonable potential to cause, or
contribute to any failure to attain the narrative water quality criteria.
The Tribe adopted narrative water quality criteria to provide additional benchmarks for protecting water
quality and an additional assessment method for identifying impaired waters. The Tribe recognizes an
inherent difference between narrative criteria and numeric, chemical-specific criteria. A major difference is the
NARRATIVE WATER QUALITY CRITERIA
Page 23
WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
manner in which the two types of criteria can be applied effectively in determining water quality-based
effluent limits for point source discharges. Chemical-specific criteria typically are expressed as a concentration
of a given parameter, with provisions that describe an averaging period and an allowable frequency of
exceedance. Narrative criteria describe a desired physical, chemical, or biological condition, and are
expressed and interpreted using information that is generally detectable by the senses and aquatic
organisms. Narrative criteria, therefore, may require additional steps and interpretations when calculating
effluent limits for point source discharges. Nevertheless, incorporating narrative criteria into assessments and
permits is vital because there can be impacts to water bodies and designated uses that are unrelated to
chemical constituents for which numeric criteria have been established.
7 NARRATIVE BIOLOGICAL CRITERIA
All tribal waters are subject to the narrative biological criteria below. The goal of the biological criteria is to
ensure the maintenance and protection of the structure and function of aquatic communities.
7.1 CRITERIA
Surface waters shall be free from substances attributable to human-caused point or nonpoint sources in
amounts, concentrations, or combinations which adversely impact the structure or function of all life stages of
aquatic or terrestrial communities. This shall include protecting, in addition to aquatic life, all life stages of
resident and migratory wildlife that use surface waters for feeding, drinking, habitat, or propagation.
7.2 IMPLEMENTATION
Assessment of biological conditions will include monitoring of the benthic macroinvertebrates, fish, and plant
communities, as appropriate. Community metrics will be determined by the Tribe relative to reference sites. A
reference condition may be assigned as a goal for the biological community if there is an insufficient number
of reference sites or if those sites become impaired. Data for a reference condition will be treated in the
same manner as if it were a reference site.
The intent of the Tribe in adopting a narrative biological criterion is to provide an additional assessment
method for the identification of impaired waters based on impacts to the structure and function of communities
and to provide protection for impacts that may not otherwise be addressed, such as from the bioaccumulation
of toxins in aquatic or terrestrial food webs. Biological criteria describe a desired biological condition and
are expressed and interpreted using information about organisms and communities of organisms. Although the
Tribe does not envision that it will always be necessary to establish effluent limits for point source discharges
based on biological criteria, the Tribe intends that the biological criteria are to be used as required by CWA
Section 301(b)(1)(C) and 40 C.F.R. Section 122.44(d) in determining appropriate effluent limits for point
source discharges. For example, where the biological criteria are not met, that information can be used by the
permitting authority to reevaluate any NPDES permits for upstream discharges to determine if all appropriate
chemical-specific and whole effluent toxicity limits are included in the permits. This may involve examining
whether such permits contain limits for all substances present in the discharge and for whatever pollutants or
parameters are or may be discharged that cause, have the reasonable potential to cause, or contribute to
any failure to meet the narrative biological criteria.
NARRATIVE BIOLOGICAL CRITERIA
Page 24
WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
8 NUMERIC CRITERIA
This section describes the numeric criteria applicable to tribal waters. Unless noted otherwise, the Tribe
adopted the National Recommended Water Quality Criteria for priority and non-priority pollutants published
by the EPA pursuant to CWA Section 304(a). They include water quality criteria for the protection of aquatic
life and human health in surface waters for approximately 150 pollutants. The 304(a) aquatic life criteria are
intended to be protective of the vast majority of the aquatic communities in the United States and Indian
reservations located therein. Where the analytical detection limit of a particular substance is greater than the
adopted numeric criterion, the applicability of the numeric criterion for regulatory purposes will be
unaffected, but enforcement decisions such as the identification of compliance thresholds to be included in
NPDES permits may be influenced.
8.1 ESTABLISHING NUMERIC CRITERIA
The Tribe establishes numeric criteria for tribal waters as follows:
1. Default numeric criteria presented in Table 20 are adopted for all segments that have been assigned
an Aquatic Life use, regardless of sub-category, unless the Tribe, following a public hearing, adopts
an alternative criterion on a site-specific basis consistent with one of the approaches described in this
section. Both acute and chronic criteria apply. Hardness-dependent criteria for metals will be
calculated as necessary using site-specific hardness information identified in Section 8.6.
2. Default numeric criteria presented in Table 21 are adopted for all segments that have been assigned
the Potable Water Supply use, unless the Tribe, following a public hearing, adopts an alternative
criterion on a site-specific basis consistent with one of the approaches described in this section.
3. For tribal waters where ambient water quality levels of one or more pollutants are higher than
applicable numeric criteria but designated uses are nevertheless supported, the Tribe may adopt sitespecific or seasonal ambient criteria. Ambient chronic criteria shall be set at the 90th percentile of the
available representative data. Ambient acute criteria shall be based on the default values in this
document. In no case may an ambient chronic criterion be less stringent than the acute criterion.
4. The Tribe may adopt site-specific numeric criteria applicable to all or part of a segment. A sitespecific criterion is intended to come closer than the national criterion to provide the intended level of
protection to the aquatic life at the site, usually by taking into account the biological or chemical
conditions (i.e., the species composition or water quality characteristics) at the site. Accordingly, any
site-specific criteria shall be developed based on relevant site-specific conditions such as:
a. actual species at a site are more or less sensitive than those used in the national criteria data
set;
b. physical or chemical characteristics at a site such as pH, temperature or hardness alter the
biological availability or toxicity of the pollutant;
c. physical, biological or chemical factors alter the bioaccumulation potential of a pollutant;
d. the concentration resulting from natural background exceeds numeric criteria for aquatic life
or other uses; or
e. other factors or combination of factors that may warrant modification of the default criteria,
subject to EPA review and approval.
Site-specific criteria must fully protect the designated use to which they apply. In the case of human
health-organism only criteria, site-specific criteria must fully protect human health when organisms are
NUMERIC CRITERIA
Page 25
WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
consumed from waters containing pollutants. In special cases where protection of designated uses
requires criteria not provided by the normal water quality requirements above, site-specific criteria
may be assigned after public notice and hearing. Examples where special protection may be
necessary include but are not limited to wildlife preserves, water bodies endangered by
eutrophication, and waters of special cultural significance to the Tribe.
Any party may petition the Tribe to adopt site-specific criteria by submitting a petition with the
following information:
a. identify the specific waters to which the site-specific criteria would apply;
b. explain the rationale for proposing the site-specific criteria;
c. describe the methods used to notify and solicit input from potential stakeholders and from the
general public in the affected area, and present and respond to the public input received;
and
d. present and justify the derivation of the proposed criteria.
A derivation of site-specific criteria shall rely on a scientifically defensible method such as one of the
following:
a. the “Resident Species Procedure,” as described in the Water Quality Standards Handbook:
Second Edition (EPA-823-B-94-005a; August 1994);
b. the “Recalculation Procedure,” or the “Water-Effect Ratio Procedure,” as updated in the
Water Quality Standards Handbook: Third Edition (EPA-823-B-17-001; 2017);
c. the Biotic Ligand Model as described in Aquatic Life Ambient Freshwater Quality Criteria –
Copper 2007 Revision (EPA-822-R-07-001; February 2007); and
d. the Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human
Health (EPA-822-B-00-004; October 2000) and associated Technical Support Documents.
Proposed third party revisions for site-specific criteria will be evaluated by the Tribe and may be proposed
to the public during the next water quality standards rulemaking opportunity. Site-specific criteria revisions
are final and applicable for use only after adoption by the Tribe and CWA review and approval by EPA.
8.2 POTABLE AND INDUSTRIAL WATER SUPPLY
The numeric criteria for the protection of human health in surface water (Table 21) apply to all waters
designated for Potable Water Supply use. The policy of the Tribe is that tribal waters designated for use as
a potable water supply shall not contain substances in concentrations that create a lifetime cancer risk of more
than one cancer occurrence per 1,000,000 exposed persons based on a fish consumption rate of 22
grams/day. Numeric criteria for such segments shall at minimum meet that cancer risk threshold. No unique
numeric criteria apply to Industrial Water Supply (IND) uses at this time.
8.3 PRIMARY CONTACT RECREATION
The monthly maximum geometric mean of E. coli bacteria of 126 cfu/100 mL and statistical threshold value
maximum of 410 cfu/100 mL and pH within the range of 6.5 to 9.0 apply to segments designated as Primary
Contact Recreation (REC1).
NUMERIC CRITERIA
Page 26
WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
The maximum Water + Organism measurement of Microcystins of 8 (µg/L) and maximum Water + Organism
measurement of Cylindrospermopsin of 15 (µg/L) apply to primary contact recreation waters.
8.4 SECONDARY CONTACT RECREATION
The monthly maximum geometric mean of E. coli bacteria of 126 cfu/100 mL and statistical threshold value
maximum of 410 cfu/100 mL apply to segments designated as Secondary Contact Recreation (REC2).
The maximum Water + Organism measurement of Microcystins of 8 (µg/L) and maximum Water + Organism
measurement of Cylindrospermopsin of 15 (µg/L) apply to secondary contact recreation waters.
8.5 AQUATIC LIFE
In addition to the narrative water quality criteria and narrative biological criteria, the acute and chronic
aquatic life criteria identified in Table 20 apply to all segments designated for Aquatic Life use. In addition,
the specific criteria for aquatic life subcategories in the following paragraphs apply to waters classified
under the respective designations.
Table 15. Aquatic Life Temperature Designations (Class 1 and 2)
Temperature
Class
Max Daily
Temp
Cold Water
Dissolved
Oxygen
(Min Value)
6 mg/L (6.5)***
pH
Specific
Conductance
20°C (68°F)*
Maximum
Weekly
Average Temp
17°C (63°F)**
6.5 - 9.0
200--1,600 µS/cm
Cool Water
6 mg/L (6.0)***
24°C (75°F)*
21°C (70°F)**
6.5 - 9.0
200--1,600 µS/cm
Warm Water 5 mg/L (6.0)***
30°C (86°F)*
27°C (81°F)**
6.5 - 9.0
200--1,600 µS/cm
* Acute Temperature - Duration: 2 hours. Frequency: not to exceed more than once in 3 years.
** Chronic Temperature – Duration: 7-day mean of multiple, equally spaced, daily temperatures.
Frequency: not to exceed more than once in 3 years.
*** (Min Value) are instantaneous concentrations to be achieved at all times. Values in parenthesis
represents the 7-day mean value.
*** These values represent the intergravel dissolved oxygen concentrations for proper development of
embryonic and larval stages for aquatic species. See table 20, Footnote “L” for further clarification.
In some circumstances, aquatic life uses may be supported even where, occasionally, these criteria are not
met. An appropriate assessment procedure shall be used to identify when such excursions are or may be
impairing aquatic life. The objective of the specific conductance criterion, provided as a range, is to prevent
excessive increases in dissolved solids that could result in changes in community structure. The criterion applied
to a particular water body will depend on its estimated natural background concentration and meeting that
objective.
8.6 HARDNESS-DEPENDENT CRITERIA FOR METALS
Hardness-dependent acute and chronic criteria for selected metals apply to all segments designated for
Aquatic Life use. The criteria, which are a function of dissolved hardness (as mg CaCO3/L) measured in the
water body, are calculated using the equations specified in this section and the coefficient values listed in
Table 18. Unless noted otherwise, they are equivalent to the National Recommended Water Quality Criteria
published by EPA pursuant to CWA Section 304(a).
NUMERIC CRITERIA
Page 27
WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
1. Acute aquatic life criteria for metals in µg/L of dissolved metal:
CMC = (exp(mA[ln(hardness)] + bA))CF
2. Chronic aquatic life criteria for metals in ug/L of dissolved metal:
CCC = (exp(mC[ln(hardness)] + bC))CF
Where CMC refers to Acute Criteria and CCC refers to Chronic Criteria, CF is the conversion factor used for
converting a metal criterion expressed as the total recoverable fraction in the water column to a criterion
expressed as the dissolved fraction in the water column, and mA, bA, mC, and bC are metal-specific
coefficients listed in Table 16 . Table 17 provides examples of the criteria for each metal at various levels of
hardness. The equations are valid only for dissolved hardness concentrations of 0-400 mg/L. For dissolved
hardness concentrations above 400 mg/L, the criteria for 400 mg/L apply.
Table 16. Hardness Dependent Parameters for Calculating Freshwater Dissolved Metals Acute and Chronic Criteria
Metal
mA
bA
mC
bC
Conversion
factor (CF) CMC
Conversion
factor (CF) CCC
1.136672 -
1.101672 -
Cadmium (Cd)
0.9789
-3.866
0.7977
-3.909
[(ln hardness) *
(0.041838)]
[(ln hardness) *
(0.041838)]
Chromium (Cr) III
0.8190
3.7256
0.8190
0.6848
0.316
0.860
1.46203 -
1.46203 -
Lead (Pb)
1.273
-1.460
1.273
-4.705
[(ln hardness) *
(0.145712)]
[(ln hardness) *
(0.145712)]
Nickel (Ni)
0.8460
2.255
0.8460
0.0584
0.998
0.997
Silver (Ag)
1.72
-6.59
-
-
0.85
-
Zinc (Zn)
0.8473
0.884
0.8473
0.884
0.978
0.986
Table 17. Selected Values of Calculated Acute and Chronic Criteria (µg/L).
Hardness (mg/L CaCO3)
25
50
75
100
150
200
250
300
350
400
Acute
0.52
1.03
1.52
2.01
2.99
3.95
4.90
5.85
6.80
7.74
Chronic
0.09
0.15
0.20
0.25
0.33
0.40
0.46
0.53
0.59
0.64
Cadmium
NUMERIC CRITERIA
Page 28
WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
Chromium III
Acute
183
323
450
570
794
1005
1207
1401
1590
1773
Chronic
24
42
59
74
103
131
157
182
207
231
Acute
14
30
47
65
100
136
172
209
245
281
Chronic
0.5
1.2
1.8
2.5
3.9
5.3
6.7
8.1
9.5
10.9
Acute
145
260
367
468
660
842
1017
1186
1351
1513
Chronic
16
29
41
52
73
93
113
132
150
168
Acute
0.30
0.98
1.96
3.22
6.46
10.60
15.56
21.28
27.75
34.91
Acute
36
65
92
117
165
211
255
297
339
379
Chronic
36
66
93
118
167
213
257
300
341
382
Lead
Nickel
Silver
Zinc
8.7 AMMONIA NUMERICAL CRITERIA FOR ALL SEGMENTS DESIGNATED
FOR AQUATIC USE
Table 18. Equation Used for Numerical Criteria of Total Ammonia Nitrogen (“TAN”).
mg TAN/L
Acute (CMC) equation
(1 hour average)
Chronic (CCC) equation
(30-day rolling
average)*
Note: Ammonia criteria are a function of pH and temperature. At the standard normalized pH of 7.0 and
temperature of 20 oC, the acute criterion would be 17 mg TAN/L and the chronic criterion would be 1.9 mg
TAN/L. Criteria duration: the acute criterion is a one-hour average and the chronic criterion is a thirty-day rolling
average. Criteria frequency: Not to be exceeded more than once in 3 years.
* Not to exceed 2.5 times the CCC as a 4-day average within the 30-days, i.e. 4.8 mg TAN/L at pH 7 and 20 oC
more than once in 3 years on average.
NUMERIC CRITERIA
Page 29
WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
Note to Ammonia Numerical Criteria: Acute (CMC) and chronic (CCC) freshwater ammonia criteria were
developed using EPA’s 2013 Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater (EPA–
822–R–13–001), which is hereby incorporated by reference. Illustrations, tables, and formulae used in the
development of these equations can be found on pages 40-52 of the criteria document. Alternative equations
for the presence or absence of Oncorhynchus sp. (rainbow trout) can be found on pages 41-42 of the
document.
8.8 SELENIUM AQUATIC LIFE CRITERIA FOR FRESH WATERS
Table 19. Selenium Numerical Criteria.
Criterion Element
Fish Tissuea (Egg-Ovary)b
Magnitude
15.1 mg/kg dw
Fish Tissuea
(Whole Body or Muscle)d
8.5 mg/kg dw
or
11.3 mg/kg dw muscle
(skinless, boneless filet)
1.5 µg/L in lentic aquatic
systems
Water Columne
(Monthly Average
Exposure)
Water Columne
(Intermittent Exposure)f
3.1 µg/L in lotic aquatic
systems
WQCint =
WQC30-day – Cbkgrnd(1 – fint)
fint
Duration
Instantaneous
measurementc
Instantaneous
measurementc
Frequency
Not to be
exceeded
Not to be
exceeded
30 days
Not more than
once in three
years on average
Number of
days/month with an
elevated
concentration
Not more than
once in three
years on average
a
Fish tissue elements are expressed as steady-state.
Egg/ovary supersedes any whole-body, muscle, or water column element when fish egg/ovary
concentrations are measured.
c
Fish tissue data provide point measurements that reflect integrative accumulation of selenium over
time and space in fish population(s) at a given site.
d
Fish whole-body or muscle tissue supersedes water column element when both fish tissue and
water concentrations are measured.
e
Water column values are based on dissolved total selenium in water and are derived from fish tissue
values via bioaccumulation modeling. Water column values are the applicable criterion element in the
absence of steady-state condition fish tissue data.
f
Where WQC30-day is the water column monthly element, for either lentic or lotic waters; Cbkgrnd is the
average background selenium concentration, and fint is the fraction of any 30-day period during which
elevated selenium concentrations occur, with fint assigned a value ≥0.033 (corresponding to 1 day).
g
Fish tissue studies and implementation decisions will be based on EPA’s Final Criterion: Aquatic Life
Ambient Water Quality Criterion for Selenium- Freshwater (June 30, 2016, 822-R-16-006).
b
9 NUMERIC CRITERIA TABLES
The Tribe has adopted the National Recommended Water Quality Criteria for freshwater pollutants
published by EPA pursuant to CWA Section 304(a).
NUMERIC CRITERIA TABLES
Page 30
WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
9.1 NUMERIC CRITERIA FOR AQUATIC LIFE
Table 20 below lists acute (CMC) and chronic (CCC) criteria for the protection of aquatic life. They apply to
all water designated for aquatic life use, regardless of sub-category. Hardness-dependent criteria for certain
metals are discussed in Subsection 8.6 above. All criteria are expressed in dissolved fractions unless otherwise
noted.
Table 20. Numeric Criteria for the Protection of Aquatic Life in Surface Water.
Pollutant
Acrolein
AldrinA
AlkalinityB
alpha-EndosulfanA,C
AluminumD
Ammonia
ArsenicE,F
beta-EndosulfanA,C
CadmiumF
Carbaryl
ChlordaneA
Chloride
Chlorine
Chlorpyrifos
Chromium (III)F
Chromium (VI)F
CopperG
Cyanide H
Demeton
Diazinon
DieldrinA
EndrinI
gamma-BHC (Lindane)
Guthion
Heptachlor A
Heptachlor Epoxide A,J
Iron
LeadF
Malathion
MercuryF,K
Methoxychlor
Mirex
NickelF
Nonylphenol
Oxygen, Dissolved L
Parathion
PentachlorophenolM
CAS Number
107028
309002
959988
7429905
7664417
7440382
33213659
7440439
63252
57749
16887006
7782505
2921882
16065831
18540299
7440508
57125
8065483
333415
60571
72208
58899
86500
76448
1024573
7439896
7439921
121755
22967926 or 7439976
72435
2385855
7440020
84852153
7782447
56382
87865
NUMERIC CRITERIA TABLES
CMC (acute) - µg/L N
3
3.0
0.22
CCC (chronic) - µg/L N
3
20000
0.056
See Table 18
340
0.22
150
0.056
See Table 16
2.1
2.4
860000
19
0.083
2.1
0.0043
230000
11
0.041
See Table 16
16
11
22
0.17
0.24
0.086
0.95
0.52
0.52
-
5.2
0.1
0.17
0.056
0.036
0.01
0.0038
0.0038
1000
See Table 16
1.4
-
0.1
0.03
0.001
See Table 16
28
6.6
See Table 15
0.065
19
0.013
15
Page 31
WATER QUALITY STANDARDS
FOR SURFACE WATERS ON THE SOUTHERN UTE INDIAN RESERVATION
Pollutant
pH
Selenium
SilverA,F
Sulfide-Hydrogen
Sulfide
Temperature
Toxaphene
Tributyltin (TBT)
ZincF
4,4'-DDTA
CAS Number
7782492
7440224
7783064
CMC (acute) - µg/L N
CCC (chronic) - µg/L N
6.5 – 9
See Table 19
See Table 16
-
Cold, Cool, and Warm Water Matrix – See
Section 8.5
0.73
0.0002
0.46
0.072
See Table 16
1.1
0.001
8001352
7440666
50293
-
2
Aquatic Life Table – Footnotes
A. These criteria are based on the 1980 criteria, which used different Minimum Data Requirements and
derivation procedures from the 1985 Guidelines. If evaluation is to be done using an averaging
period, the acute criteria values given are not to be exceeded and should be divided by 2 to obtain
a value that is more comparable to a CMC derived using the 1985 Guidelines.
B. The CCC of 20mg/L is a minimum value except where alkalinity is naturally lower, in which case the
criterion cannot be lower than 25% of the natural level.
C. This value was derived from data for endosulfan and is most appropriately applied to the sum of
alpha-endosulfan and beta-endosulfan.
D. Freshwater criteria for aluminum shall be developed using EPA’s 2018 Final Aquatic Life Ambient
Water Quality Criteria for Aluminum (December 2018, EPA 822-R-18-001).
E. This recommended water quality criterion was derived from data for arsenic (III) but is applied here
to total arsenic.
F. Freshwater and saltwater criteria for metals are expressed in terms of the dissolved metal in the
water column. See Office of Water Policy and Technical Guidance on Interpretation and
Implementation of Aquatic Life Metals Criteria. See Table 1a for conversion factors.
G. Acute (CMC) and chronic (CCC) freshwater copper criteria shall be developed using EPA’s 2007
Aquatic Life Ambient Freshwater Quality Criteria—Copper (EPA–822–R–07–001), which incorporates
use of the copper biotic ligand model (BLM). Where sufficiently representative ambient data for
DOC, calcium, magnesium, sodium, potassium, sulfate, chloride, or alkalinity are not available, the
Tribe shall use the values from the Draft Technical Support Document: Recommended Estimates for
Missing Water Quality Parameters for Application in EPA’s Biotic Ligand Model, March 2016, EPA
820-E-15-106, which is hereby incorporated by reference. If taking stream order into account, the
Tribe will use Tables 8, 9, and 10 of the document; for estimates irrespective of stream order, the
state or tribe will refer to Table 4.
H. These recommended water quality criteria are expressed as µg free cyanide (CN/L).
I. The derivation of the CCC for this pollutant did not consider exposure through the diet, which evidence
suggests is important for aquatic life occupying upper trophic levels.
J. This value was derived from data for heptachlor and there was insufficient data to determine relative
toxicities of heptachlor and heptachlor epoxide.
K. This recommended water quality criterion was derived from data for inorganic mercury (II), but is
applied here to total dissolved mercury. If a substantial portion of the mercury in the water column is
methylmercury, this criterion will probably be under protective. In addition, even though inorganic
NUMERIC CRITERIA TABLES
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WATER QUALITY STANDARDS
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mercury is converted to methylmercury and methylmercury bioaccumulates to a great extent, this
criterion does not account for uptake via the food chain because sufficient data were not available
when the criterion was derived.
L. For fresh waters, see Quality Criteria for Water, 1986 ("Gold Book"), for protection of early live
stages.
M. Freshwater aquatic life values for pentachlorophenol are expressed as a function of pH and values
displayed in table correspond to a pH of 7.8. CCC = e 1.005(pH) – 5.134, CMC = e 1.005 (pH) – 4.869
N. Criteria duration: the acute criterion is instantaneous, and the chronic criterion is a thirty-day rolling
average. Criteria frequency: Not to be exceeded more than once in 3 years.
9.2 NUMERIC CRITERIA FOR HUMAN HEALTH
Table 21 lists numeric criteria for surface water to protect human health from ingesting water and resident
organisms and for ingesting resident organisms only. The calculated human health criteria are based on a fish
consumption rate of 22 grams/day and cancer risk level of 1 in 1,000,000 people (10-6) and applies to all
waters designated for Potable Water Supply use.
Table 21. Numeric Criteria for the Protection of Human Health in Surface Water.
Pollutant
CAS Number
Water + Organism (µg/L) J
Organism Only (µg/L) J
1,1,1-Trichloroethane A
71556
10000
200000
1,1,2,2-Tetrachloroethane
79345
0.2
3
1,1,2-Trichloroethane A
79005
0.55
8.9
1,1-Dichloroethylene A
75354
300
20000
1,2,4,5-Tetrachlorobenzene
95943
0.03
0.03
1,2,4-Trichlorobenzene A
120821
0.071
0.076
1,2-Dichlorobenzene A
95501
1000
3000
1,2-Dichloroethane A
107062
9.9
650
1,2-Dichloropropane
78875
0.90
31
1,2-Diphenylhydrazine
122667
0.03
0.2
1,2-Trans-Dichloroethylene A
156605
100
4000
1,3-Dichlorobenzene
541731
7
10
NUMERIC CRITERIA TABLES
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WATER QUALITY STANDARDS
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Pollutant
CAS Number
Water + Organism (µg/L) J
Organism Only (µg/L) J
1,3-Dichloropropene
542756
0.27
12
1,4-Dichlorobenzene A
106467
300
900
2,3,7,8-TCDD (Dioxin)
1746016
5.0e-9
5.1e-9
2,4,5-Trichlorophenol B
95954
300
600
2,4,6-Trichlorophenol B
88062
1.5
2.8
2,4-Dichlorophenol B
120832
10
60
2,4-Dimethylphenol B
105679
100
3000
2,4-Dinitrophenol
51285
10
300
2,4-Dinitrotoluene
121142
0.049
1.7
2-Chloronaphthalene
91587
800
1000
2-Chlorophenol B
95578
30
800
2-Methyl-4,6-Dinitrophenol
534521
2
30
3,3'-Dichlorobenzidine
91941
0.049
0.15
3-Methyl-4-Chlorophenol B
59507
500
2000
4,4'-DDD
72548
0.00012
0.00012
4,4'-DDE
72559
0.000018
0.000018
4,4'-DDT
50293
0.000030
0.000030
Acenaphthene B
83329
70
90
Acrolein
107028
3
400
Acrylonitrile
107131
0.061
7.0
Aldrin
309002
7.7e-7
7.7e-7
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WATER QUALITY STANDARDS
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Pollutant
CAS Number
Water + Organism (µg/L) J
Organism Only (µg/L) J
alpha-BHC
319-84-6
0.00036
0.00039
alpha-Endosulfan
959988
20
30
Anthracene
120127
300
400
Antimony A,C,D
7440360
5.6
640
Arsenic
7440382
0.018
0.14
Asbestos A,C,E
1332214
7 million fibers/L
--
Barium A,C,E,F
7440393
1000
--
Benzene A
71432
0.58
16
Benzidine
92875
0.00014
0.011
Benzo(a) Anthracene
56553
0.0012
0.0013
Benzo(a) Pyrene A
50328
0.00012
0.00013
Benzo(b) Fluoranthene
205992
0.0012
0.0013
Benzo(k) Fluoranthene
207089
0.012
0.013
beta-BHC (beta-HCH)
319857
0.0080
0.014
beta-Endosulfan
33213659
20
40
Bis(2-Chloro-1-Methylethyl)
Ether
108601
200
4000
Bis(2-Chloroethyl) Ether
111444
0.030
2.2
Bis(2-Ethylhexyl) Phthalate A
117817
0.32
0.37
Bis(Chlormethyl) Ether
542881
0.00015
0.017
Bromoform A
75252
7.0
120
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Pollutant
CAS Number
Water + Organism (µg/L) J
Organism Only (µg/L) J
Butylbenzyl Phthalate
85687
0.10
0.10
Carbon Tetrachloride A
56235
0.4
5
Chlordane A
57749
0.00031
0.00032
Chlorobenzene A,B
108907
100
800
Chlorodibromomethane A
124481
0.80
21
Chloroform A
67663
60
2000
Chlorophenoxy Herbicide
(2,4,5-TP) [Silvex] A
93721
100
400
Chlorophenoxy Herbicide (2,4D) A
94757
1300
12000
Chrysene A
218019
0.12
0.13
Copper A, B, C, E
7440508
1300
--
57125
4
400
Cylindrospermopsin K
143545-90-8
15
--
Di-n-Butyl Phthalate
84-74-2
20
30
Dibenzo(a,h) Anthracene
53703
0.00012
0.00013
Dichlorobromomethane A
75274
0.95
27
Dieldrin
60571
0.0000012
0.0000012
Diethyl Phthalate
84662
600
600
Dimethyl Phthalate
131113
2000
2000
Dinitrophenols
25550587
10
1000
Endosulfan Sulfate
1031078
20
40
Cyanide A
NUMERIC CRITERIA TABLES
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WATER QUALITY STANDARDS
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Pollutant
CAS Number
Water + Organism (µg/L) J
Organism Only (µg/L) J
Endrin
72208
0.03
0.03
Endrin Aldehyde A
7421934
1
1
Ethylbenzene A
100414
68
130
Fluoranthene
206440
20
20
Fluorene
86737
50
70
Gamma-BHC (HCH); Lindane A
58899
4.2
4.4
Heptachlor A
76448
0.0000059
0.0000059
Heptachlor Epoxide A
1024573
0.000032
0.000032
Hexachlorobenzene A
118741
0.000079
0.000079
Hexachlorobutadiene A
87683
0.01
0.01
Hexachlorocyclohexane (HCH) Technical
608731
0.0066
0.010
Hexachlorocyclopentadiene A,B
77474
4
4
Hexachloroethane
67721
0.1
0.1
Indeno(1,2,3-cd) Pyrene
193395
0.0012
0.0013
Isophorone
78591
34
1800
Manganese B,C,G,E
7439965
50
100
Methoxychlor A
72435
0.02
0.02
Methyl Bromide
74839
100
10000
Methylene Chloride A
75092
20
1000
Methylmercury C,H
22967926
N/A
0.3 mg/Kg
NUMERIC CRITERIA TABLES
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WATER QUALITY STANDARDS
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Pollutant
CAS Number
Water + Organism (µg/L) J
Organism Only (µg/L) J
Microcystin K
101043-37-2
8
--
N-Nitrosodi-n-Propylamine C
621647
0.0050
0.51
N-Nitrosodimethylamine C
62-75-9
0.00069
3.0
N-Nitrosodiphenylamine C
86306
3.3
6.0
Nickel C,D
7440020
610
4600
Nitrates A,C,E
14797558
10000
--
Nitrobenzene B
98953
10
600
Nitrosamines C
70-25-7
0.0008
1.24
Nitrosodibutylamine C
924-16-3
0.0063
0.22
Nitrosodiethylamine C
55-18-5
0.0008
1.24
Nitrosopyrrolidine C
930-55-2
0.016
34
Pentachlorobenzene
608935
0.1
0.1
Pentachlorophenol (PCP) A,B
87865
0.03
0.04
pH C,E
-
5-9
--
Phenol B
108952
4000
300000
Polychlorinated Biphenyls (PCBs)
1336-36-3
0.000064
0.000064
A,C,I
Pyrene
129000
20
30
Selenium A,C
7782492
170
4200
-
250000
--
127184
10
29
Solids Dissolved and Salinity C,E
Tetrachloroethylene A
NUMERIC CRITERIA TABLES
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WATER QUALITY STANDARDS
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Pollutant
CAS Number
Water + Organism (µg/L) J
Organism Only (µg/L) J
Thallium
7440280
0.24
0.47
Toluene A
108883
57
520
Toxaphene A
8001352
0.00070
0.00071
Trichloroethylene A
79016
0.6
7
Vinyl Chloride A
75014
0.022
1.6
Zinc B,C
7440666
7400
26000
Footnotes for Numerical Criteria for Human Health:
A. Epa has issued a Maximum Contaminant Level (MCL) for this chemical which may be more stringent.
See EPA's National Primary Drinking Water Regulations.
B. The criterion for organoleptic (taste and odor) effects may be more stringent. See National
Recommended Water Quality Criteria - Organoleptic Effects.
C. EPA's National Recommended Human Health Water Quality Criteria for this pollutant were not
updated in 2015.
D. This criterion was revised to reflect EPA's q1* or RfD as contained in the Integrated Risk Information
System (IRIS) as of May 17, 2002. The fish tissue bioconcentration factor (BCF) is from the 1980
Ambient Water Quality Criteria document.
E. Criteria for these pollutants are from the National Recommended Water Quality Criteria - Human
Health Criteria Table. They are not calculated based on this table's inputs for fish consumption rate
and cancer risk level.
F. This human health criterion is the same as originally published in the Quality Criteria for Water, 1976
("Red Book") which predates the 1980 methodology and did not utilize the fish ingestion BCF
approach. This same criterion value is published in the Quality Criteria for Water, 1986 ("Gold
Book").
G. The Human Health for the consumption of Water + Organism criterion for manganese is not based on
toxic effects, but rather is intended to minimize objectionable qualities such as laundry stains and
objectionable tastes in beverages.
H. This fish tissue residue criterion for methylmercury is based on the total fish consumption rate of
0.0175 kg/day.
I. This criterion applies to total PCBs (e.g., the sum of all congener or all isomer or homolog or Aroclor
analyses).
J. Criteria duration: instantaneous. Criteria frequency: Not to be exceeded.
K. This criterion is valid for implementation with a duration of ‘1 sampling event within any 10-day
assessment period across a recreational season’ and an exceedance frequency not to exceed 3
excursions in a recreational season in more than one year. An excursion is defined as a 10-day
assessment period with any toxin concentration higher than the recommended criteria magnitude.
When more than three excursions occur within a recreational season and that pattern reoccurs in more
than one year, it is an indication the water quality has been or is becoming degraded and is not
supporting its recreational use. Methods for sampling, data management, and assessment are included
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WATER QUALITY STANDARDS
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in an EPA-approved Quality Assurance Program Plan (QAPP). Should they be necessary, public
advisories will be drafted by EPD, reviewed and approved by Tribal governance, and distributed via
the Tribe’s electronic information services.
10 WATER QUALITY STANDARDS FOR WETLANDS
All tribal waters that are wetlands, unless a constructed wetland, shall be subject to the level of protection as
defined by the designated uses assigned to the river or stream segment to which they are hydraulically
connected. Wetlands shall be presumed to provide habitat capable of supporting aquatic biota (e.g., fish,
macroinvertebrates, amphibians, or hydrophytic vegetation) on a regular or periodic basis. It shall be a goal
of the Tribe to maintain the water quality, functions, and values of wetlands at naturally occurring levels,
within the natural range of variation for the individual wetland. The functions and values that shall be
maintained include, but are not limited to, the following:
1. Storm and flood water storage and retention and the moderation of water level fluctuation extremes;
2. Filtration or storage of sediments, nutrients or toxic substances that would otherwise adversely impact
the quality of other waters of the Tribe;
3. Shoreline protection against erosion through the dissipation of wave energy and water velocity and
anchoring of sediments;
4. Habitat for aquatic organisms in the food web including, but not limited to, fish, crustaceans, mollusks,
insects, annelids, planktonic organisms and the plants and animals upon which these aquatic organisms
feed and depend upon for their development in all life stages;
5. Habitat for resident and transient wildlife species, including mammals, birds, reptiles and amphibians
for breeding, resting, nesting, escape cover, travel corridors and food; and
6. Recreational, culturally significant wetland plant species, educational, scientific and natural scenic
beauty values and uses.
Wetlands shall be subject to narrative criteria, numeric criteria, and applicable antidegradation provisions.
For substances that are not naturally occurring, water quality requirements shall be based on protecting
designated uses of the wetland consistent with antidegradation requirements, the Tribe’s narrative water
quality criteria, narrative biological criteria, criteria assigned to hydraulically-connected surface waters, or
appropriate criteria guidance issued by EPA. The Tribe recognizes and expects that certain parameters may
exceed applicable numeric criteria in wetlands due to natural forces and variability. Wetlands, except for
constructed wetlands, shall not be permitted as repositories or treatment systems for wastes from human
sources.
11 OUTSTANDING TRIBAL RESOURCE WATERS
Outstanding Tribal Resource Water (OTRW) means a segment that has been classified as an OTRW pursuant
to the provisions of these water quality standards and any procedures the Tribe adopts specific to OTRW.
The intent of OTRW classification is to provide enhanced protection for certain waters. OTRW segments may
include, but are not limited to, waters that have outstanding water quality, unique aquatic ecology, or
recreational, cultural, ceremonial or aesthetic characteristics that qualify them for such classification by the
Tribe. In addition to the numeric and narrative criteria for other applicable designated uses, waters classified
as an OTRW shall be subject to the water quality requirements specified below and to tier 3 review under the
Tribe’s antidegradation review policies and procedures.
WATER QUALITY STANDARDS FOR WETLANDS
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WATER QUALITY STANDARDS
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1. To qualify as an OTRW, following nomination from a member of the public or tribal personnel, the
Tribal Council must make a finding that a tribal water is a unique tribal resource based upon one of
the following criteria:
a. The tribal water is of exceptional recreational or ecological significance because of its unique
attributes including, but not limited to, those related to cultural values, geology, flora, water
quality, aesthetic value, or its wilderness characteristics.
b. Threatened or endangered species are known to be associated with the tribal water. The
existing water quality is essential to the maintenance and propagation of a threatened or
endangered species or provides critical habitat. Threatened and endangered species can be
those identified under the Endangered Species Act, ones listed by the State of Colorado, or
any additional species status designated by the Tribe.
2. The disclosure to the public of the existence and location of waters that qualify as an OTRW may
result in visitation and impacts that are not consistent with the objectives of OTRW classification.
Accordingly, the Tribe may, in the interest of protection of these waters, limit the public disclosure of
any OTRW classification, the information supporting such classification, and the basis of the decision.
The Tribe will develop procedures and policies to govern the confidential classification and
administration of such waters, and the OTRW classifications will be made available to interested
parties upon request in accordance with these procedures and policies.
3. The following water quality requirements apply to each OTRW, regardless of whether it is
confidential. These water quality requirements are supplemental to the narrative and numeric water
quality criteria associated with all other applicable designated uses for the water body.
Table 22. These water quality requirements apply to all Outstanding Tribal Resource Waters.
Constituent
Standard
Dissolved oxygen
No observable change caused by discharge
pH
No observable change caused by discharge
Temperature
No observable change caused by discharge
Total dissolved solids
No observable change caused by discharge
Total nitrogen
No observable change caused by discharge
Total phosphorus
No observable change caused by discharge
All numerical criteria
No observable change caused by discharge
The water quality requirement of “No observable change caused by discharge” will be implemented
through the antidegradation review process and through incorporation into applicable NPDES permits
for point source discharges and through required, enforceable BMPs for nonpoint sources.
4. The Tribe may adopt site-specific water quality standards to maintain and protect water quality in
OTRWs.
OUTSTANDING TRIBAL RESOURCE WATERS
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WATER QUALITY STANDARDS
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12 ANALYTICAL METHODS
All methods of analysis used to measure the water quality of surface waters for purposes of determining
compliance with these standards shall be in accordance with procedures prescribed in the current 40 C.F.R.
part 136.
13 ANTIDEGRADATION REVIEW POLICIES AND PROCEDURES
13.1 ANTIDEGRADATION POLICY
Antidegradation refers to the mechanism to review the potential water quality impacts of existing or
proposed activities; then to take actions that ensure that existing uses and water quality will be maintained or
improved or ensure public notification and comment before allowing any degradation to occur. The Tribe’s
Antidegradation Policy is based on the three-tiered federal antidegradation policy found in 40 C.F.R. Section
131.12. The antidegradation policy applicable to all tribal waters is as follows:
Tier 1 - Existing uses and the level of water quality necessary to protect the existing uses shall be
maintained and protected.
Tier 2 - Where the quality of the waters exceeds a level of quality necessary to support propagation
of fish, shellfish, and wildlife and recreation in and on the water, that quality shall be maintained and
protected unless the Tribe finds, after appropriate intergovernmental coordination and public
participation, that allowing lower water quality is necessary to accommodate important economic or
social development in the area in which the waters are located. In allowing such degradation or lower
water quality, the Tribe shall assure water quality adequate to protect existing uses fully. Further, the
Tribe shall assure that there shall be achieved the highest statutory and regulatory requirements for
all new and existing point sources and all cost-effective and reasonable best management practices
for nonpoint source water pollution control.
Before allowing any degradation of water quality, pursuant to 40 C.F.R. Section 131.12 (a)(2), the
Tribe will find, after an analysis of alternatives, that such a lowering is necessary to accommodate
important economic or social development in the area in which the waters are located. The analysis of
alternatives will evaluate a range of practicable alternatives that would prevent or lessen the
degradation associated with the proposed activity. When the analysis of alternatives identifies one or
more practicable alternatives, the Tribe will only find that a lowering is necessary if one such
alternative is selected for implementation.
Tier 3 - Where a tribal water has been classified an OTRW, that water quality shall be maintained
and protected.
In those cases where potential water quality impairment associated with a thermal discharge is involved, the
antidegradation policy and implementing method shall be consistent with CWA Section 316, 33 U.S.C. Section
1326. Among other things, Section 316 requires effluent limits for thermal discharges and any interacting
pollutants that assure the protection and propagation of a balanced, indigenous population of fish and
wildlife.
ANALYTICAL METHODS
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WATER QUALITY STANDARDS
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13.2 ANTIDEGRADATION IMPLEMENTATION PROCEDURES
See Appendix A, Antidegradation Implementation Procedures, for specific procedures governing tribal review
and approval of a proposed regulated activity that may have some effect on surface water quality and
Antidegradation Review Worksheet for a worksheet intended to facilitate each antidegradation review.
14 VARIANCES FROM WATER QUALITY STANDARDS
A variance is a short-term exemption from meeting certain otherwise applicable components of these water
quality standards. EPA authorizes tribes to include variances in their water quality standards for CWA
purposes. See 40 C.F.R. Section 131.13. The Tribe has adopted these variance policies and procedures to
avoid the potential for unreasonable consequences where a water quality standard may not be attainable on
a near-term basis, yet it represents an attainable goal. The Tribe’s intent is to encourage maintenance of
adopted standards as goals as an alternative to removing or putting in place a standard that represents a
lesser goal than can reasonably be attained should conditions change (e.g., technological improvements allow
for improved treatment of a particular discharge at a reasonable cost). Therefore, the objective of this policy
and procedure is (1) to provide for the proper issuance of variances when information demonstrates that such
unreasonable consequences may arise, (2) to limit the possibility that a variance will be inappropriately relied
upon when a current standard is reasonably achievable, and (3) to ensure the highest level of water quality
achievable during the term of any variance that is granted.
Because a variance is a revision to these water quality standards that may involve temporarily removing a
designated use as it relates to a particular discharge or activity, the procedures for issuing a variance involve
the same substantive and procedural requirements as removing a designated use, including public notice and
opportunity for public comment (Section 14). Variances may be justified under any of the factors listed at 40
C.F.R. Section 131.10(g) for which removing a use may be considered. But unlike removing a use, a variance is
specific to a particular discharge or regulated activity, is specific to one or more particular pollutants, is timelimited, and does not remove the currently designated use as a goal. Like all revisions to the Tribe’s water
quality standards, EPA review and approval is required of any variance before it becomes the applicable
water quality standard under the CWA. Variances are also subject to review at least every three years,
including during subsequent triennial reviews of these water quality standards by the Tribe. A variance to
these water quality standards must meet all applicable requirements at 40 C.F.R. Section 131.14.
14.1 APPLICATION
If it is not feasible for a discharge or regulated activity to comply with a component of these water quality
standards, a variance may be granted according to the requirements of this section and any other applicable
provision of these water quality standards and 40 C.F.R. 131.14. A variance temporarily modifies one or
more of the four components of these water quality standards for a specific water body (i.e., a designated
use, a numeric or narrative water quality criterion, an anti-degradation requirement, or a general policy
adopted in these water quality standards). A variance shall include an expiration date and any interim
standards that are to be effective for the duration of the variance in lieu of any otherwise applicable
standards. All other components of the water quality standards that are not modified by the variance shall
remain in effect. Any variances that are issued will be incorporated into the Tribe’s water quality standards
document as an appendix.
VARIANCES FROM WATER QUALITY STANDARDS
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WATER QUALITY STANDARDS
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14.2 REQUIREMENTS FOR A VARIANCE
1. All variances must be supported by a technical analysis demonstrating why the proposed level of
treatment for a discharge or activity is expected to cause non-compliance with one or more
components of these water quality standards (e.g., an analysis demonstrating that the attainment of a
use or criterion is not feasible), must provide for protection of the highest attainable use and water
quality condition that can be met and the most protective criteria reasonably achievable to protect
that use and water quality condition (i.e., as close to the underlying use and numeric criteria as is
achievable), and must be approved by the Tribe and EPA. In many cases, this will require the
collection and submission of site-specific water quality data sufficient to characterize conditions in
each water body that may be affected by the discharge or activity.
2. A variance for a designated use may be adopted where existing uses are protected and one or more
of the following conditions precluding the attainment of the designated use are shown to be
applicable to a specific discharge or activity:
a. naturally occurring pollutant concentrations prevent the attainment of the use;
b. natural, ephemeral, intermittent, or low-flow conditions or water levels prevent the attainment
of the use, unless these conditions may be compensated for by the discharge of sufficient
volume of effluent discharges without violating water conservation requirements to enable uses
to be met;
c. human caused conditions or sources of pollutants prevent the attainment of the use and cannot
be remedied or would cause more environmental damage to correct than to leave in place;
d. dams, diversions or other types of hydrologic modifications preclude the attainment of the use,
and it is not feasible to restore the water body to its original condition or to operate such
modification in a way that would result in the attainment of the use;
e. physical conditions related to the natural features of the water body, such as the lack of a
proper substrate, cover, flow, depth, pools, riffles, and the like, unrelated to water quality,
preclude attainment of aquatic life protection uses;
f. controls more stringent than those required by sections 301(b) and 306 of the CWA would
result in substantial and widespread economic and social impact.
g. actions necessary to facilitate lake, wetland or stream restoration through dam removal or
other significant reconfiguration activities preclude attainment of the designated use and
criterion while the actions are being implemented.
A variance to otherwise applicable water quality criteria, antidegradation requirements, or other
policies of these water quality standards must be supported with an analysis consistent with all
provisions governing those components of these water quality standards.
3. The written justification for a variance must include documentation that all reasonable alternatives to
the proposed activity or discharge and all reasonable potential controls have been evaluated to
conclude there is no reasonable alternative or control available that can be used to achieve
compliance with the otherwise applicable water quality standards during the variance term. In
particular, the proponent of a variance must evaluate treatment more advanced than that required to
meet technology based effluent limits under CWA Sections 301(b) and 306 and alternative effluent
control strategies. The justification must also include a plan to gather additional information and/or
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complete activities to remedy the conditions that preclude the attainment of designated uses, including
completing and implementing a watershed restoration plan where warranted.
4. All variances shall have an expiration date. The date shall be based upon the amount of time it is
reasonably expected will be needed to implement reasonable controls or to remedy the water
quality problem precluding compliance with the otherwise applicable water quality standards. Upon
expiration, the original, otherwise applicable water quality standards shall apply.
5. All variances shall identify interim water quality standards that are the most protective standards
reasonably achievable.
6. For variances applicable to facilities with NPDES permits, such permits should include two sets of
permit limits. One set should be at a level sufficient to achieve the interim standards, and one set
should be at a level to achieve the underlying standards upon expiration of the variance. Permit limits
for facilities for which a variance has been obtained should also be set to achieve all applicable
technology-based controls.
7. Variances and the water quality of affected water bodies shall be reviewed at least every three
years. Prior to expiration, a proponent may request that the variance be extended (through a new
variance being adopted). The Tribe shall only grant a new variance if (a) the variance is still justified
pursuant to the requirements of this section; (b) the request for a new variance meets all applicable
requirements at 40 C.F.R. 131.14; and (c) the proponent can demonstrate that it has ensured
achievement of the highest level of water quality achievable during the term of the variance and that
it has made reasonable progress to comply with the otherwise applicable water quality standards.
This shall include re-evaluating all reasonable alternatives to the activity or discharge and all
reasonable potential controls (e.g., new, or improved treatment technologies).
8. Any party requesting a variance must provide the proposed terms of the variance, any required
technical analyses, and any other information reasonably required by the Tribe to evaluate the
request. Regardless of whether the request is ultimately successful, the Tribe may require a proponent
to pay a fee to reimburse the Tribe for its staff time and reasonable expenses incurred to evaluate
and adopt a proposed variance. Those expenses may include costs to hire a third-party expert to
evaluate the proposed variance or extension.
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APPENDIX A ANTIDEGRADATION IMPLEMENTATION
PROCEDURES
ANTIDEGRADATION IMPLEMENTATION PROCEDURES
(1) Introduction
Implementation of tribal antidegradation requirements serves to promote the maintenance and
protection of existing surface water quality. Under this program, all tribal waters are provided one of
three different levels of protection. The level of protection that is provided to a specific segment
depends upon a number of factors discussed below. At a minimum, all waters are subject to a base level
of protection referred to as tier 1 or existing use protection; some waters may qualify only for this level
of protection. Antidegradation reviews are triggered whenever a regulated activity is proposed that
may have some effect on surface water quality. Such activities are reviewed to determine, based on the
level of antidegradation protection afforded to the affected water body segment, whether the
proposed activity should be authorized and under what conditions. All information, correspondence and
notifications regarding antidegradation reviews are to be directed to the Water Quality and
Remediation Division Head, Environmental Programs Department, Southern Ute Indian Tribe, P.O. Box
737 #81, 71 Mike Frost Way, Ignacio, Colorado 81137.
(a)
Scope
The Tribe will conduct some level of antidegradation review for all “regulated activities” (see definition in
Section I.7) that have the potential to affect existing water quality. The specifics of the review will
depend upon the water body segment that would be affected, the tier of antidegradation applicable to
that water body segment, and the extent to which existing water quality would be degraded.
The sequence of steps to be completed in conducting an antidegradation review is summarized in Figure
1. In conducting an antidegradation review, the first task is to determine which tier of antidegradation
applies. This is accomplished, as described in detail below, based on whether an OTRW designation has
been assigned to the segment (i.e., subject to tier 3) and whether the existing quality of the segment is
better than necessary to support aquatic life and/or recreation uses (i.e., subject to tier 2). The Tribe then
determines whether authorizing the proposed activity would be consistent with tribal antidegradation
requirements. The major conclusions of the review are documented using the antidegradation worksheet
found in Appendix B. Based upon the review findings, a preliminary decision is made by the Tribe and
subjected to intergovernmental coordination and public participation. Public participation occurs
regardless of the outcome of the preliminary decision (i.e., whether the proposed activity would be
authorized or denied). The Tribe then considers public comments and reaches a final decision regarding
whether to authorize the proposed activity pursuant to the antidegradation requirements. The substance
and basis of the final decision by the Tribe are documented in the administrative record.
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(b)
Information Required from Applicants
The applicant will be required to provide information, including monitoring data, sufficient to evaluate
the potential effects of the proposed activity on water quality and complete the antidegradation review
process. The information that will be required in a given situation will be identified on a case-by-case
basis by the Tribe. Such information may include recent ambient chemical, physical, and biological
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monitoring data sufficient to characterize, during the appropriate critical condition(s), the existing uses
and the spatial and temporal variability of existing quality of the segment for the parameters that
would be affected by the proposed regulated activity, as well as the water quality that would result if
the proposed activity were authorized. Approaches and procedures similar to those used in watershedscale cleanup or restoration plans may be the basis for identifying needed information, interpreting
available data, or for characterizing existing water quality and projecting future water quality.
(2)
TIER 3 PROCEDURES
(a)
Direct Sources to OTRWs: Prohibition on New or Expanded Sources
Any proposed activity that would result in a permanent new or expanded direct source of pollutants to
any segment which has been designated as an OTRW is prohibited. This prohibition applies to new
sources, expansion of existing sources in which treatment levels are maintained, and expansion of
existing sources in which treatment levels are increased to maintain existing pollutant loading levels.
Regardless of effluent quality, any new or expanded direct source is prohibited.
(b)
Sources Upstream of OTRWs
(i)
No Change in Water Quality Allowed
Any proposed activity that would result in a permanent new or expanded indirect source of pollutants
(i.e., an upstream source) to an OTRW segment is prohibited except where such source would have no
effect on the existing quality of the OTRW segment. Effects on OTRW water quality resulting from
upstream sources will be determined based on appropriate techniques and best professional judgment.
Factors that may be considered include: (a) percent change in ambient concentrations predicted at the
appropriate critical condition(s), (b) percent change in loadings (i.e., the new or expanded loadings
compared to total existing loadings to the segment), (c) percent reduction in available assimilative
capacity, (d) nature, persistence, and potential effects of the parameter, (e) potential for cumulative
effects, and (f) degree of confidence in the various components of any modeling technique utilized (e.g.,
associated with the predicted effluent variability).
(ii)
Trading
A proposed activity that will result in a new or expanded upstream source may be allowed where the
applicant agrees to implement or finance upstream controls of point or nonpoint sources sufficient to
offset the water quality effects of the proposed activity. Where such trading occurs upstream of an
OTRW segment, tier 3 requirements will be considered satisfied where the applicant can show that
water quality at all points within the study area will be either maintained or improved. The applicant
and Tribe must document a technical rationale for the trade that ensures a margin of safety sufficient to
offset any uncertainties (e.g., in loading reductions or effluent quality). This may be addressed using
approaches similar to those used to prepare watershed cleanup or restoration plans.
(c)
Temporary and Limited Effects
A direct or upstream source that would result in a temporary and limited effect on OTRW water quality
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may be authorized. The decision regarding whether effects will be temporary and limited will be
handled on a case-by-case basis. As a non-binding rule of thumb, activities with durations less than one
month and resulting in less than a 5% change in ambient concentration will be deemed to have
temporary and limited effects. Decisions on individual proposed activities may be based on the following
factors: (a) length of time during which water quality will be lowered, (b) percent change in ambient
concentrations, (c) parameters affected, (d) likelihood for long term water quality benefits to the
segment (e.g., as may result from dredging of contaminated sediments), (e) degree to which achieving
applicable water quality standards during the proposed activity may be at risk, and (f) potential for
any residual long term influences on existing uses.
(3)
TIER 2 PROCEDURES
(a)
Waters Qualifying for Tier 2 Protection
(i)
Qualification Criteria
The Tribe will determine whether a segment qualifies for tier 2 protection within 30 days of receiving a
complete application for a regulated activity that triggers an antidegradation review. Such decisions will
be based on all relevant information including any ambient water quality (i.e., physical, chemical,
biological) data submitted by the applicant. The criteria that will be used in identifying high quality tier
2 waters are described below.
Decisions regarding whether a water body is high quality and subject to tier 2 protection requirements
will be based on a best professional judgment of the overall quality and value of the segment. In
general, waters with existing quality that is better than necessary to support aquatic life and/or
recreation uses will be considered high quality and subject to tier 2 requirements. The factors that may
be considered in determining whether a segment satisfies the high quality test include the following: (a)
existing aquatic life uses, (b) existing recreational, cultural or aesthetic uses, (c) existing water quality for
all parameters (i.e., subject to the availability of monitoring data or other information for the segment,
upstream segments, or for comparable segments), and (d) the overall value of the segment from an
ecological and public use perspective. Note that attainment of both aquatic life (fishable) and
recreational (swimmable) uses is not required in order to qualify for tier 2 protection.
(ii)
Presumptive Applicability
In general, it is presumed that a majority of tribal waters qualify for tier 2 protection. However, there
may be some tribal waters where aquatic life and recreation goal uses are not attained. It is the intent
of these procedures to apply only existing use (tier 1) protection to such waters. There also may be tribal
waters where one or both of the goal uses are attained, but existing water quality is not “better than
necessary” to support the goal uses (i.e. assimilative capacity does not exist for a number of
parameters). It is the intent of these procedures to apply only existing use (tier 1) protection to such
waters provided that there is no assimilative capacity for each of the parameters to be affected by the
proposed activity.
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(iii)
Criteria Exceedances
Exceedances of one or more narrative or numeric water quality criteria may constitute nonattainment
sufficient to preclude tier 2 protection. For waters where exceedances have occurred and continue to
occur for one or more parameters, a judgment will be made based on the factors identified above and
in consideration of information submitted by the applicant and by the public. As a general rule, tier 2
protection will be applied even where the criteria for some parameters are not always satisfied.
(iv)
Characterizing Existing Quality
The Tribe will use available water quality data. This water quality data should be no more than 5 years
in age or the most recent available data. Characterization of existing quality will appropriately consider
spatial and temporal variability. Assimilative capacity will be identified for the appropriate critical
condition which, depending on the situation, may be at high or low flow.
(b)
Significant Degradation
(i)
Significance Factors
Once it is determined that tier 2 protection applies to a water body, the next step in the review process
is to determine whether the degradation that will result from the proposed activity is significant enough
to warrant further review. The likelihood that a proposed activity will pose significant degradation will
be judged by the Tribe for all water quality parameters that would be affected by the proposed
activity. Such significance judgments will be made on a parameter-by-parameter basis. The Tribe will
identify and eliminate from further review only those proposed activities that present insignificant threats
to water quality. Proposed activities will be considered significant and subject to tier 2 requirements
where significant degradation is projected for one or more water quality parameters. Because
determinations of significant degradation are most appropriately made based on case-specific
information, these procedures do not provide rigid decision criteria for judging significant changes in
water quality. Rather, significant degradation may be demonstrated with respect to any one (or a
combination) of the following factors: (a) percent change in ambient concentrations predicted at the
appropriate critical condition(s), (b) the difference, if any, between existing ambient quality and ambient
quality that would exist if all point sources were discharging at permitted loading rates, (c) percent
change in loadings (i.e., the new or expanded loadings compared to total existing loadings to the
segment or, for existing facilities only, the proposed permitted loadings compared to the existing
permitted loadings), (d) percent reduction in available assimilative capacity, (e) nature, persistence, and
potential effects of the parameter, (f) potential for cumulative effects, (g) predicted impacts to aquatic
biota, (h) degree of confidence in any modeling techniques utilized, (i) the difference, if any, between
permitted and existing effluent quality, and (j) the duration of the proposed activity or the expected
water quality changes.
1.
Required Analyses. Based on one or more of the significance factors identified above, the
Tribe may make determinations of significant degradation based on appropriate modeling
techniques coupled with detailed characterization of the existing background water quality.
However, determinations of significance need not be complicated, data-intensive, or resource
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intensive. It is not the intent of these procedures to require detailed analyses to address each of
the factors identified above. Where appropriate, determinations of significance may be based
on simple analyses. For example, proposed activities may be judged as insignificant where: (a)
available dilution exceeds 100:1, (b) the proposed activity would not result in a significant
increase of loadings for any parameter, (c) there is a reasonable expectation and substantial
potential for the proposed activity to result in a net long-term water quality benefit to the
segment, or (d) the projected water quality changes are temporary and limited. Likewise, a
significant increase in loading for any given parameter may be the basis for concluding that
significant degradation will occur.
2.
Persistent Toxics. The significance of proposed new or expanded sources of
bioaccumulative or other persistent toxic substances will be judged depending upon, for
example, existing loadings of the substances to the segment from all sources. The Tribe’s
interpretation of monitoring data or other information indicating fish tissue or sediment
accumulation in the watershed will be considered with respect to judging the significance of new
or expanded sources of persistent toxic substances.
(ii)
General Guidelines
As a non-binding rule of thumb, proposed activities that would lower ambient quality of any parameter
by more than 5%, reduce the available assimilative capacity by more than 5%, or increase pollutant
loadings to a segment by more than 5% will be presumed to pose significant degradation. The intent of
this guideline is to establish a de minimis test of significance and to eliminate from further review only
those proposed activities that will result in truly minor changes in water quality. Regardless of other
considerations, any proposed activity or activities that will cumulatively lower a water quality
parameter, lead to a reduction in assimilative capacity, or increase in pollutant loading greater than
10% shall be considered significant degradation.
(iii)
By-passing the Significance Test
Where available information clearly indicates that practicable non-degrading or less-degrading
alternatives to lowering existing water quality exist, the Tribe may by-pass the significant degradation
requirements and direct the applicant to demonstrate the necessity of the degradation pursuant to
section (4)(c) below.
(iv)
Trading
The Tribe may also conclude that a proposed activity will not pose significant degradation based upon
the specifics of any upstream/downstream trading that has been agreed to by the project applicant. The
applicant and Tribe must document a technical rationale for the trade that ensures a margin of safety
sufficient to offset any uncertainties (e.g., in loading reductions or effluent quality). This may be
addressed using approaches similar to those used to prepare watershed cleanup or restoration plans.
(v)
Determine Significance of Proposed Activity
Proposed regulated activities determined to be significant by the Tribe shall be subject to the tier 2
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review requirements described below. If the Tribe determines that an activity will not pose significant
degradation for any parameter, no further antidegradation tier 2 requirements shall apply; however,
such activities must still meet all technology or water quality-based control requirements or conditions of
the permit or the water quality certification.
(c)
Evaluation of Alternatives to Lower Water Quality
(i)
Role of the Tribe
The primary emphasis of the Tribe’s tier 2 antidegradation reviews will be to determine whether
practicable non-degrading or less-degrading alternatives to allowing the proposed activity are
available. The Tribe will first evaluate any alternatives analysis submitted by the applicant for
consistency with the minimum requirements described below. If an acceptable analysis of alternatives
was completed and submitted to the Tribe as part of the initial project proposal, no further evaluation of
alternatives will be required of the applicant. If an acceptable alternatives analysis has not been
completed, the Tribe will work with the project applicant to ensure that an acceptable alternatives
analysis is developed.
(ii)
Role of the Applicant
The applicant of any proposed activity that would significantly lower water quality in a tier 2 segment is
required to prepare an evaluation of alternatives. The evaluation is required, at a minimum, to provide
substantive information pertaining to the costs and environmental impacts associated with the following
alternatives: (a) pollution prevention measures; (b) reduction in scale of the project, (c) water recycle or
reuse, (d) process changes, (e) innovative treatment technology, (f) advanced treatment technology, (g)
seasonal or controlled discharge options to avoid critical water quality periods, (h) improved operation
and maintenance of existing treatment system, and (i) alternative discharge locations.
(iii)
Preliminary Determination
Once the Tribe has determined that feasible alternatives to allowing the degradation have been
adequately evaluated, the Tribe shall make a preliminary determination regarding whether practicable
non-degrading or less-degrading alternatives are available. This determination will be based primarily
on the alternatives analysis developed by the project applicant, but may be supplemented with other
information or data. If the Tribe determines that practicable alternatives to allowing the degradation do
not exist, the Tribe shall continue with the tier 2 review and document the substance and basis for that
preliminary determination using the antidegradation review worksheet.
(iv)
If Practicable Alternatives Exist
If the Tribe makes a preliminary determination that one or more practicable alternatives to allowing the
degradation exists, the Tribe will work with the project applicant to revise the project design. If a
mutually-acceptable resolution cannot be reached, the Tribe will document the alternatives analysis
findings and provide public notice of a preliminary decision, based on antidegradation tier 2
requirements, to deny the activity.
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(v)
Role of Public
Based upon comments and information received during the public comment period, the Tribe may reverse
its preliminary determination regarding the availability of practicable alternatives to allowing the
degradation.
(d)
Determination of Socio-Economic Importance
(i)
Role of the Applicant
The applicant is required to demonstrate the social and economic importance of the proposed activity.
The factors to be addressed in such a demonstration may include, but are not limited to, the following:
(a) employment (i.e., increasing, maintaining, or avoiding a reduction in employment), (b) increased
production, (c) improved community tax base, (d) housing, and (e) correction of environmental or public
health concern.
(ii)
Role of the Tribe
Prior to authorizing any proposed activity that would significantly lower the water quality of a tier 2
water, the Tribe shall ensure that the proposed activity will provide important social or economic
development in the area in which the waters are located. In making a preliminary determination, the
Tribe will rely primarily on the demonstration made by the applicant. However, the Tribe may weigh the
applicant’s demonstration against counterbalancing socio-economic costs associated with the proposed
activity, such as projected negative socio-economic effects on the community and projected environmental
effects (i.e., those determined in the significance or alternatives analysis decision processes).
(iii)
Additional Information Requirements
If information available to the Tribe is not sufficient to make a preliminary determination regarding the
socio-economic costs or benefits associated with the proposed activity, the Tribe may require the project
applicant to submit specific items of information needed to support a determination of importance. The
types of information required of the applicant will be determined on a case-by-case basis, but may
include: (a) information pertaining to current aquatic life, recreational, or other water body uses, (b)
information necessary to determine the environmental impacts that may result from the proposed activity,
(c) facts pertaining to the current state of economic development in the area (e.g., population, area
employment, area income, major employers, types of businesses), (d) government fiscal base, and (e)
land use in the areas surrounding the proposed activity.
(iv)
Mitigation
The applicant may voluntarily submit a proposal to mitigate the adverse environmental effects of the
proposed activity (e.g., in-stream habitat improvement, bank stabilization/upgraded riparian
vegetation). Such mitigation plans should describe the proposed mitigation measures and the costs of such
mitigation. Such a mitigation plan will not release the Tribe from its obligation to require any practicable
non-degrading or less-degrading alternative under this procedure, nor should such plans have any effect
on the effluent limitations to be included in any NPDES permit (except possibly where a previously-
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completed mitigation project has resulted in an improvement in background water quality that affects the
water quality-based limit). Such mitigation plans will be developed and implemented by the applicant
as a means to further minimize the environmental effects of the proposed activity and to increase its
socio-economic importance. It is anticipated that an effective mitigation plan may, in some cases, allow
the Tribe to conclude “importance” and to authorize proposed activities that could otherwise not be
authorized pursuant to the Tribe’s antidegradation requirements. Mitigation plans should include criteria
for determining success of the mitigation, legal commitment for follow-up monitoring and additional work
if necessary, and where practicable, a commitment to implement the mitigation before the project and
water quality degradation are allowed.
(v)
Preliminary Determination
Once the tribe has reviewed available information pertaining to the socio-economic importance of the
proposed activity, the Tribe shall make a preliminary determination regarding importance. If the Tribe
determines that the proposed activity has social or economic importance in the area in which the affected
waters are located, the Tribe shall continue with the tier 2 review and document the substance and basis
for that preliminary determination using the antidegradation review worksheet.
(vi)
If Importance is Found Lacking
If the Tribe makes a preliminary determination that the proposed activity does not have social or
economic importance in the area in which the affected water is located, the Tribe will document that
antidegradation review finding and provide public notice of a preliminary decision, based upon
antidegradation tier 2 requirements, to deny the proposed activity.
(vii)
Role of Public
Because the socio-economic importance of a proposed activity is a question best addressed by local
interests, the Tribe will give particular weight to the comments submitted by local governments, land use
planning authorities, and other local interests in determining whether the balancing of benefits and costs
were an appropriate basis for the Tribe’s preliminary decision. Based upon comments and information
received during the public comment period, the Tribe may reverse its preliminary decision regarding the
social or economic importance of a proposed activity.
(e)
Ensure Full Protection of Existing Uses
Prior to authorizing any proposed activity that would significantly degrade a tier 2 water, the Tribe shall
ensure that existing uses will be fully protected consistent with the tier 1 implementation procedures
provided below.
(f)
Ensure Implementation of Tribe-Required Point and Nonpoint Source Controls
(i)
Role of Tribe
Prior to authorizing a regulated activity that would significantly degrade a tier 2 water, the Tribe shall
determine that compliance with required controls on all point and nonpoint sources in the zone of
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influence has been assured. This requirement is intended to ensure that regulated activities that will result
in water quality degradation for a particular parameter will not be authorized where there are existing
unresolved compliance problems involving the same parameter in the zone of influence of the proposed
activity. The “zone of influence” is determined as appropriate for the parameter of concern, the
characteristics of the receiving water body (e.g., lake versus river, etc.), and other relevant factors.
Where available, a watershed-scale restoration plan may be the basis for identifying the appropriate
zone of influence. The Tribe may conclude that such compliance has not been assured where facilities are
in noncompliance with their NPDES permit limits. However, the existence of schedules of compliance for
purposes of NPDES permit requirements will be taken into consideration in such cases. Where there are
nonpoint sources that are regulated activities, the Tribe shall determine that any Tribe-required controls
or BMPs have been achieved or that a plan that assures such compliance has been developed. In other
words, required controls on existing regulated sources in the area need not be finally achieved prior to
authorizing a proposed activity provided there is reasonable assurance of future compliance.
(ii)
Preliminary Determination
Based upon available data or other information, the Tribe will make a preliminary determination
regarding whether compliance with required controls on point and nonpoint sources in the zone of
influence has been assured. If the preliminary determination is that such compliance has been assured,
the Tribe shall continue with the tier 2 review and document the substance and basis for that preliminary
determination using the antidegradation review worksheet.
(iii)
Controls have not been Assured
If the Tribe makes a preliminary determination that compliance with required point and nonpoint source
controls has not been assured, the Tribe shall document that antidegradation review finding and provide
public notice of a preliminary decision based upon tier 2 requirements, to deny the proposed activity.
(iv)
Role of Public
Based upon comments and information received during the public comment period, the Tribe may reverse
its preliminary decision regarding the degree to which compliance with required point and nonpoint
source controls has been assured.
(4)
TIER 1 PROCEDURES
(a) Waters Subject to Tier 1 Requirements
All tribal waters are subject to tier 1 protection. Those which are only subject to tier 1 protection are
those waters that have not been classified as an OTRW and that do not currently possess the overall
water quality or value necessary to meet the tier 2 applicability test. In general, tier 1-only waters are
those segments where fishable and swimmable goal uses are not attained, or where assimilative
capacity does not exist for any of the parameters that would be affected by the proposed activity.
(b)
Two-Part Requirement: Protect Water Quality and Uses
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The tribal antidegradation policy requires that existing uses, and the water quality necessary to protect
existing uses, shall be maintained and protected.
(c)
Ensure Water Quality Necessary to Maintain and Protect Existing Uses
(i)
Confirm that Designated Uses Address Existing Uses
Prior to authorizing any proposed activity, the Tribe shall ensure that water quality sufficient to protect
existing uses fully will be achieved. The Tribe must decide whether the water body currently supports, or
has supported since November 28, 1975, an existing use that has more stringent water quality
requirements than the currently designated uses. In making this decision, the Tribe will focus on whether a
higher designated use (i.e., based on the tribal use designations) should be assigned to the water body
to reflect an existing use. Where the Tribe determines that the currently designated uses appropriately
reflect the existing water body uses, the Tribe shall document that preliminary determination using the
antidegradation review worksheet. In such cases, the water quality control requirements necessary to
protect designated uses will be presumed to also fully protect existing uses.
Where the designated uses are found to be appropriate but there is clear and convincing evidence that
the numeric criteria adopted would not adequately protect existing uses, the Tribe may either app
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