SOUTHERN UTE INDIAN TRIBE (2026)

SOUTHERN UTE INDIAN TRIBE

AIR QUALITY DIVISION

ANNUAL NETWORK REVIEW

Calendar Year 2026

Prepared For:

United States Environmental Protection Agency

Region VIII

1595 Wynkoop Street

Denver, Colorado 80202

Prepared By:

Southern Ute Indian Tribe

Environmental Programs Department

Air Quality Division

P.O. Box 737, MS#84

Ignacio, Colorado 81137

(970) 563-4705

July 6th, 2026

Contents

1.0

Introduction ........................................................................................................................ 4

1.1

Overview .......................................................................................................................... 4

1.2

Personnel .......................................................................................................................... 4

1.3

Overview of Monitored Parameters – Criteria Pollutants ................................................ 5

2.0

Monitoring Objectives ....................................................................................................... 6

3.0

Air Monitoring Network ................................................................................................... 7

3.1.

Ute 1 Air Monitoring Station ........................................................................................... 9

3.1.1

3.2.

Recommendations for Ute 1 .................................................................................... 11

Ute 3 (Bondad) Monitoring Station ............................................................................... 12

3.2.2

3.3.

Recommendations for Ute 3 .................................................................................... 13

Lake Capote (MMS) Monitoring Station ...................................................................... 14

3.3.1

Recommendations for MMS .................................................................................... 16

4.0

Quality Assurance ............................................................................................................ 16

5.0

Summary........................................................................................................................... 17

6.0

Final Comments ............................................................................................................... 17

Appendices

Appendix A – Population Demographics and Areas Served

Appendix B – 2025 Regulatory Air Monitoring Data

Appendix C – 2026 Equipment List – Southern Ute Indian Tribe Air Monitoring Stations

SUIT AIR QUALITY DIVISION – CY2026 NETWORK REVIEW

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List of Tables

TABLE 1. MONITORING STATION IDENTIFICATION..................................................................................... 8

TABLE 2. UTE 1 CY2025 MEASURED AMBIENT CONCENTRATIONS IN COMPARISON TO THE NAAQS ......................... 10

TABLE 3. UTE 3 CY2025 MEASURED AMBIENT CONCENTRATIONS IN COMPARISON TO THE NAAQS ......................... 13

TABLE 4. MMS CY2025 MEASURED AMBIENT CONCENTRATIONS IN COMPARISON TO THE NAAQS. ......................... 15

List of Figures

FIGURE 1 - MAP OF SOUTHERN UTE RESERVATION WITH LOCATION OF AIR MONITORING STATIONS ..................7

FIGURE 2 - NORTHWESTERN VIEW OF THE UTE 1 STATION ..........................................................................................................9

FIGURE 3 – UTE 1 METEOROLOGICAL TOWER AND WEATHER RESISTANT, SURGE PROTECTED ENCLOSURE BOX (LEFT). THE THIRTY-FOOT

METEOROLOGICAL TOWER (RIGHT). ............................................................................................................................. 11

FIGURE 4 – NORTHERN VIEW OF UTE 3 MONITORING STATION ..................................................................................................12

FIGURE 5 - MOBILE MONITORING STATION ...........................................................................................................................14

SUIT AIR QUALITY DIVISION – CY2026 NETWORK REVIEW

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ACRONYMS AND ABBREVIATIONS

AQI

AQD

BCF

CAA

CFR

CH4

CO

EPA

FEM

FRM

MET

MMS

NAAQS

NIST

NMHC

NO2

NO

NOx

NPAP

O3

PM2.5

PM10

PPB

PPM

QAPP

SLAMS

SO2

SOP

SPMS

SRM

SUIT

ug/m3

VOC

Air Quality Index

Air Quality Division

Billion Cubic Feet

Clean Air Act

Code of Federal Regulations

Methane

Carbon Monoxide

Environmental Protection Agency

Federal Equivalent Methods

Federal Reference Method

Meteorological

Mobile Monitoring Station

National Ambient Air Quality Standards

National Institute of Standards and Technology

Non-methane Hydrocarbon

Nitrogen Dioxide

Nitric Oxide

Oxides of Nitrogen

National Performance Audit Program

Ozone

Particulate Matter less than or equal to 2.5 microns

Particulate Matter less than or equal to 10 microns

Parts per Billion

Parts per Million

Quality Assurance Project Plan

State and Local Air Monitoring Stations

Sulfur Dioxide

Standard Operating Procedure

Special Purpose Monitoring Station

Standard Reference Method

Southern Ute Indian Tribe

Micrograms per cubic meter

Volatile Organic Compound

SUIT AIR QUALITY DIVISION – CY2026 NETWORK REVIEW

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CY2026 Network Review

Air Monitoring Program

Southern Ute Indian Tribe

July 2026

1.0

Introduction

The purpose of this Annual Network Review (ANR) document is to provide information concerning the operation of the ambient air monitoring network by the Southern Ute Indian Tribe’s (SUIT)

Air Quality Division (AQD) in calendar Year 2026.

In October 2006, US EPA issued final regulations concerning state and local agency ambient air

monitoring networks. Under 40 CFR, Part 58, Subpart B, applicable tribes are required to submit

an annual monitoring network review to the Environmental Protection Agency (EPA) regional

office. This network review is required to provide the framework for establishment and maintenance of an air quality surveillance system. This network plan is required to list any changes that

are proposed to take place to the current network during the following year. The annual monitoring

network review must be made available for public review for at least 30 days prior to submission

to EPA.

1.1

Overview

Located in southwestern Colorado, the SUIT AQD regulates air quality through implementation

of Clean Air Act programs to protect public health and the environment on the Southern Ute Indian

Reservation (Reservation). Air monitoring data are used (1) to determine compliance with U.S.

EPA’s National Ambient Air Quality Standards (NAAQS) and (2) for generation of real-time EPA

Air Quality Index (AQI) air quality forecasts and public health notifications, (3) identification of

localized air quality related health risk concerns, and (4) tracking long-term trends in air quality.

1.2

Personnel

In 2025, all air quality monitoring activities were conducted by the Tribe’s Environmental Programs Department – AQD staff. The Air Quality Division Head directs and provides managerial

direction to the air quality programs. The Air Quality Program Manager provides managerial and

technical direction to the ambient monitoring program and verifies data quality. The day-to-day

activities of the ambient monitoring program are implemented by the Air Quality Specialist.

SUIT AIR QUALITY DIVISION – CY2026 NETWORK REVIEW

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1.3

Overview of Monitored Parameters – Criteria Pollutants

Nitrogen Dioxide

Nitrogen Dioxide (NO2) is a reddish-brown gas that is a respiratory irritant that causes eye and

sinus irritation. It is created primarily during fuel combustion from industrial sources and vehicles.

It can react in the atmosphere to form nitrate aerosols that block sunlight and reduce visibility. Of

most interest to the AQD, NO2 is a precursor pollutant in the photochemical reaction between

nitrogen oxides and volatile organic compounds (VOCs) and sunlight which is responsible for

ground-level ozone formation. Monitoring this pollutant could help the AQD estimate the influence of anthropogenic NO2 emissions in the formation of ozone on the Reservation.

Ozone

Ground-level ozone (O3), a constituent of photochemical smog, is not emitted into the atmosphere

directly, but rather is formed by the reactions of other pollutants. The primary precursor pollutants

involved in this reaction are VOCs and oxides of nitrogen. These precursors form O3 in the presence of sunlight. O3 is a strong irritant of the upper respiratory system and causes damage to crops.

Ozone is a pollutant of concern on the Reservation, as historically, O3 concentrations on the Reservation have been relatively near the 2015 ozone NAAQS of 70 parts per billion (ppb)

Fine Particulate Matter

The occurrence of fine particulate matter with a diameter of 2.5 microns or less (PM2.5) on the

Reservation is a result of exceptional events such as forest fires events and dust storms, and in

some occurrences, prescribed forest burns. These particles can travel deep into the lungs. Exposure

to particle pollution is linked to a variety of significant health problems ranging from aggravated

asthma to premature death in people with heart and lung disease. PM2.5 is of particular concern and

interest of the AQD, due to the frequent occurrence of high PM2.5 concentrations during local and

regional forest fire events and dust storms. Because the events that contribute to PM2.5 concentrations on the Reservation are primarily exceptional events, outside of the control of the AQD, the

monitoring of this pollutant is non-regulatory, and for the purpose of informing the public of unhealthy air quality in real-time, and not for the purpose of evaluating compliance with the NAAQS.

Particulate Matter

The occurrence of particulate matter with a diameter of 10 microns or less (PM10) on the Reservation is, like PM2.5, a result of exceptional events such as forest fires events and dust storms, and in

some occurrences, prescribed forest burns. Exposure to PM10 can induce tissue damage, and lung

inflammation. PM10 is of great concern and interest of the AQD, due to the frequent occurrence of

high PM10concentrations during local and regional forest fire events and dust storms. Because the

events that contribute to PM10concentrations on the Reservation are primarily exceptional events,

outside of the control of the AQD, the monitoring of this pollutant is non-regulatory, and for the

purpose of informing the public of unhealthy air quality in real-time, and not for the purpose of

evaluating compliance with the NAAQS.

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2.0

Monitoring Objectives

The monitoring program has been designed to respond to the needs of the Reservation, while adhering to strict EPA specifications and regulations, including the monitoring objectives of Appendix D of 40 CFR Part 58, Section 2. General Monitoring Requirements as required by 40 CFR Part

58.10. Monitoring is conducted to:

•

•

•

•

•

Continuously collect ambient air pollutant and meteorological data according to the quality

assurance requirements of the Code of Federal Regulations, particularly, but not limited,

to appendix A in 40 CFR Part 58.

Submit all quality assurance reviewed data to the EPA Air Quality Systems (AQS) database for use by the federal agencies, the State of Colorado, the Tribe or other outside agencies for air quality studies and air quality planning.

Demonstrate compliance with the National Ambient Air Quality Standards (NAAQS).

Help protect the health and welfare of all residents within the exterior boundaries of the

Reservation through population of real-time air pollution monitoring data and corresponding EPA Air Quality Index (AQI) health alerts on the Tribe’s website.

Identify localized health concerns and track long-term trends in air quality.

Although the Reservation does not meet the requirement of a Metropolitan Statistical Area with a

population greater than 350,000 in 40 CFR Part 58.50 Air Quality Index (AQI) requirements, the

AQD participates in AirNow. Data from all three monitoring stations is uploaded and available

online, allowing the public to view the AQI for the Reservation.

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3.0

Air Monitoring Network

The AQD has established three State and Local Air Monitoring Stations (SLAMS). The Ute 1

station is located in the town of Ignacio, the Ute 3 station is located on the central-western portion

of the Reservation near Bondad, and the Mobile Monitoring Station (MMS) is currently located

toward the northeastern corner of the Reservation, near Lake Capote. The AQD monitors four of

the six NAAQS criteria pollutants, however, the AQD’s PM monitoring is non-regulatory. The

regulatorily pollutants monitored are: NO2 and O3. The non-regulatorily pollutants that are monitored for informing tribal members and the public of air quality health issues are: (PM10 and PM2.5).

(Table 1.) Carbon monoxide (CO), and Sulfur Dioxide (SO2) are not monitored because the AQD

has monitored these pollutants in the past and determined that levels are far below the NAAQS

and not likely to increase due to any identified anthropogenic (human caused) emissions sources.

Carbon monoxide monitoring was discontinued in CY2024 and the justification for discontinuing

monitoring of this pollutant was described in the ANR prepared for that year. SO2 monitoring was

discontinued in CY2023, and the justification for discontinuing monitoring of this pollutant was

described in the ANR prepared for that year. The Tribe does not monitor Lead as the Reservation

currently does not meet the criteria for monitoring this pollutant under the requirements of §4.1

Lead (Pb) Design Criteria and § 10(a)(4) of 40 CFR 58. Meteorological (MET) parameters are

obtained at all three of the monitoring stations per §§1.2(c) of 40 CFR 58, Appendix D.

Figure 1 - Map of Southern Ute Reservation with Location of Air Monitoring Stations

SUIT AIR QUALITY DIVISION – CY2026 NETWORK REVIEW

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All three monitoring stations are equipped with an Agilaire 8872 data acquisition system connected

to the gaseous analyzers, meteorological (sensors, and other diagnostic sensors. Gas analyzers are

challenged regularly during automated calibration events that make use of Teledyne T700 calibrators, T701 Zero Air Generators, and National Institute of Standards and Technology (NIST) traceable calibration gas cylinders with known concentrations of each species. Continuous data for all

parameters is recorded locally at each individual station and centrally on a main server located in

Ignacio, Colorado. All historical data is stored on the central server and can be retrieved at will.

This type of set-up has enabled the AQD to collect data with increased accuracy and precision and

has reduced errors and system faults as they are now identified and corrected with minimal downtime.

The NetAssess2025 app, which was developed by the EPA’s Office of Air Quality Planning and

Standards (NetAsess 2025 Application)is used to determine the demographics and area served for

the two SLAMS, the Ute 1 and Ute 3 stations and the one Special Purpose Monitoring Station

(SPMS), the MMS. This data is in each station’s respective section and Appendix A.

In CY2024 the AQD was awarded the Section 60105 Inflation Reduction Act (IRA) Air Monitoring Grant. The intent of the IRA grant is for the replacement of aging or outdated air monitoring

instrumentation, sensors, and equipment. In CY2025, the AQD utilized funding from the IRA grant

to purchase new gas analyzers and calibrators for all three of the AQD’s stations. The Thermo

Scientific 49i O3 and 42i NO/NO2/NOx gaseous analyzers were replaced with Teledyne Model

T400 O3 and Model T200 NO/NO2/NOx gaseous analyzers and the Teledyne T700 Dynamic Dilution Calibrators were replaced with new T700 calibrators. A new Teledyne Model T640 Particulate Mass Monitor was also installed at the Ute 3 station. All new instrumentation was put into

operation in May of 2025. The new instruments have remote access capabilities, through Teledyne

NumaView software, making off-site maintenance and calibrations accessible. A set of the Thermo

42i and 48i analyzers were saved for any instances when the Teledyne instruments become inoperable or are in need of repair.

Site identification information for each monitoring station is listed below in Table 1.

Table 1. Monitoring Station Identification

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SUIT Site

Designation

EPA-AQS

Number

Ute 1

08-067-7001

Ute 3

08-067-7003

MMS

08-007-7004

3.1.

Type

Street Address

Geographic

Coordinates

CY2025 Air

Pollutants

Monitored

SLAM

1 MI. NE of

Ignacio, County RD. 517.

Ignacio, CO 81137

37.13678, 107.62863

NOx, O3,

PM2.5, PM10

SLAM

7571 Hwy. 550.

Ignacio, CO 81137

37.10258, 107.870219

NOx, O3,

PM2.5, PM10,

Visibility

SPM

398 CO-151,

Pagosa Springs, CO

81147

37.205717, 107.254234

NOx, O3

Ute 1 (Ignacio) Monitoring Station

The Ute 1 station is located approximately one mile north of Ignacio,

Colorado. The station is situated in

the Pine River Valley, the most

densely populated area of the Reservation (Figure 1).

The Ute 1 station meets all siting

criteria for an urban SLAMS for

measuring typical pollutant concentration in an area of high population

density area, as outlined by §§

1.1.1.(b) & 1.2.(b)(4) of 40 CFR 58,

Appendix D.

Ute 1 station serves a population of

approximately 9,262 and an area of Figure 2 - Northwestern view of the Ute 1 station

283 mi2 (733km2) for NO2 and O3.

Demographics of this area are calculated in EPA’s NetAssess 2025 application and are included

in Appendix A.

This station is in a secured area within the Southern Ute Indian Tribe Forestry complex.

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The Ute 1 station (Figure 2) is thought by AQD to be representative of the air quality in and around

the Ignacio community and is likely to be affected by local activities such as vehicle traffic, ongoing building and road construction, and winter residential wood and coal burning. Residential

burning and traffic are the most influential local sources that directly impact the air quality around

the Ignacio community. The Ute 1 station serves a valuable purpose of providing real-time air

pollutant concentrations and corresponding EPA AQI health advisories to residents of Ignacio on

the Tribe’s website. The town of Ignacio is frequently impacted by high particulate concentrations

from local, regional, and western forest fires and dust storms. Additionally, the region, at times,

experiences elevated O3 values. Ozone and NO2 data collected at the Ute 1 station is designated as

regulatory data and is used for determining compliance with the NAAQS.

40 CFR 58.10(a)(5)(i) outlines the requirement for NO2 monitoring. The AQD utilizes a Teledyne

Model T200 NO/NO2/NOx analyzer following EPA Federal Reference Method (FRM) RFNA1194-099 to monitor NO2, NOx, and NO. The AQD monitors this pollutant to help the AQD estimate the influence of anthropogenic NO2 emissions in the formation of ozone on the Reservation

as well as determining regulatory compliance with the NO2 NAAQS.

40 CFR 58.10(a)(9) outlines the requirement for O3 monitoring. The AQD utilizes a Teledyne

Model T400 Photometric O3 Analyzer following EPA FRM EAOA-0992-087 to monitor for regulatory compliance with the O3 NAAQS.

A Teledyne T640 PM Mass Monitor sampler using EPA FRM EQPM-0516-240 collects continuous non-regulatory measurements of PM2.5 and PM10 for the purpose of helping inform individual

decision making that will lead to reduced PM exposure in the region from wildfire smoke and dust

storms. Because occurrences of high PM concentrations on the Reservation are solely a result of

exceptional events, the PM sampling data at Ute 1 station is designated as non-regulatory and not

used for NAAQS compliance determinations.

The criteria air pollutants measured at the Ute 1 station for the purpose of NAAQS compliance

determinations are listed in Table 2. All criteria pollutants monitored by the AQD in the most

recent complete year of data, CY2025, have remained below the current NAAQS.

Table 2. Ute 1 CY2025 Measured Ambient Concentrations in Comparison to the NAAQS

Instrument Type**

Reference

Method

Parameter

Teledyne Model

T200 NO/NO2/NOx

RFNA-1194-099

and

EQOA-0880-047

NO2

NAAQS

CY2025 *

Concentrations

53 ppb (annual)

3.56

ppb

100 ppb (1-hour)

15.2

ppb

SUIT AIR QUALITY DIVISION – CY2026 NETWORK REVIEW

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analyzer and

Thermo 42i

Teledyne Model

EAOA-0992-087

T400 Photometric

and

O3

0.070 ppm (8-hour)

0.066 ppm

O3 Analyzer and

EQOA-0880-047

Thermo 49i

* CY25 data is included in this document because it is the most current full year of data collected at the Ute

1 station. 2026 data is not complete or certified by the date of this review.

** The Thermo Instruments were operating from January to May 19th before being replaced with Teledyne

Gas Analyzers

The Ute 1 station continues to collect meteorological data for the following parameters: solar radiation, wind speed, wind direction, ambient temperature, humidity, and precipitation. A new meteorological tower was installed in June of CY2025 that utilizes a wench system to lower and raise

the tower. The wench system and new tower are more accessible to raise and lower making maintenance, verification, and calibration of meteorological instruments safer and more consistent. All

the meteorological instruments, except for the precipitation gauge, are located on the 30-foot tiltover aluminum met tower. The peripherals of the meteorological instruments are housed in a

weather-resistant, surge protected enclosure box affixed to the base of the tower (Figure 3).

Figure 3 – Ute 1. Meteorological tower and weather resistant, surge protected enclosure box (left).

The thirty-foot meteorological tower (right).

3.1.1 2026 Recommendations for Ute 1

At the Ute 1 station, the AQD recommends continuation of monitoring for NO2, O3, PM10 , PM2.5

and meteorological parameters. In CY2026 and CY2027, the AQD recommends using any addi-

SUIT AIR QUALITY DIVISION – CY2026 NETWORK REVIEW

11

tional funding for upgrading and replacement of meteorological instruments, and zero air generator.

3.2.

Ute 3 (Bondad) Monitoring Station

The Ute 3 station is located approximately twenty miles west of

Ignacio, near Bondad, Colorado.

The Ute 3 station meets all siting

criteria for an urban SLAMS for

measuring typical pollutant concentration in an area of high population density area, as outlined

by §§ 1.1.1.(b) & 1.2.(b)(4) of 40

CFR 58, Appendix D.

The Ute 3 station serves a population of approximately 50,993 and

an area of 2,889mi2 (7,482km2)

for NO2, and an area of 1,138mi2

(2,947km2) with a population of

approximately 41,942 for O3.

Figure 4 – Northern view of Ute 3 monitoring station

Although Ute 3 does not serve Ignacio, Colorado because of the Ute 1 station being located in

Ignacio, due to the scarcity of SLAMS in western Colorado. Demographics of this area were calculated in EPA’s NetAssess 2025 application and are included in Appendix A.

The Ute 3 station is located on Tribal land within a locked perimeter fence and the area is regularly

patrolled by Southern Ute Tribal Rangers.

The Ute 3 station is situated along the eastern rim of the Animas River Valley near Highway 550,

a major roadway that connects southwestern Colorado with northwestern New Mexico (Figure

1.).

The Ute 3 station (Figure 4) is likely to be affected by activities such as highway vehicle traffic,

road construction, agricultural activities, and oil and gas production sites.

40 CFR 58.10(a)(5)(i) outlines the requirement for nitrogen dioxide monitoring. The AQD utilizes

a Teledyne Model T200 NO/NO2/NOx analyzer following EPA FRM RFNA-1194-099 to monitor

NO2, NOx, and NO. The AQD monitors this pollutant to estimate the influence of anthropogenic

SUIT AIR QUALITY DIVISION – CY2026 NETWORK REVIEW

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NO2 emissions in the formation of ozone on the Reservation as well as determining regulatory

compliance with the NO2 NAAQS.

40 CFR 58.10(a)(9) outlines the requirement for O3 monitoring. The AQD utilizes a Teledyne

Model T400 Photometric O3 Analyzer following EPA FRM EAOA-0992-087 to monitor for regulatory compliance with the O3 NAAQS.

A Teledyne T640 PM Mass Monitor using EPA FRM EQPM-0516-240 collects continuous nonregulatory measurements of PM2.5 and PM10 for the purpose of helping inform individual decision

making that will lead to reduced PM exposure in the region from wildfire smoke and dust storms.

The criteria air pollutants measured at the Ute 3 station for the purpose of NAAQS compliance

determinations are listed in Table 3. All criteria pollutants monitored by the AQD in the most

recent complete year of data, CY2025, have remained below the current NAAQS.

Table 3. Ute 3 CY2025 Measured Ambient Concentrations in Comparison to the NAAQS

Instrument Type**

Reference

Method

Parameter

NAAQS

CY2025 *

Concentrations

Teledyne Model

53 ppb (annual)

3.77 ppb

RFNA-1194-099

T200 NO/NO2/NOx

and

NO2

analyzer and

100 ppb (1-hour)

16.5 ppb

EQOA-0880-047

Thermo 42i

Teledyne Model

EAOA-0992-087

T400 Photometric

and

O3

0.070 ppm (8-hour)

0.066 ppm

O3 Analyzer and

EQOA-0880-047

Thermo 49i

* CY25 data is included in this document because it is the most current full year of data collected at the Ute

3 station. 2026 data is not complete or certified by the date of this review

** The Thermo Instruments were operated from January to May 19th before being replaced with Teledyne

Gas Analyzers

The Ute 3 station continues to collect meteorological data for the following parameters: solar radiation, wind speed, wind direction, ambient temperature, humidity, and precipitation. A new

meteorological tower was installed in June of CY2025 that utilizes a wench system to lower the

tower. The wench system and new tower are more accessible to raise and lower making maintenance, verification, and calibration of meteorological instruments safer and more consistent. All

the meteorological instruments, except for the precipitation gauge, are located on the 30-foot tiltover aluminum met tower. The peripherals of the meteorological instruments are housed in a

weather-resistant, surge protected enclosure box affixed to the base of the tower (Figure 3).

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3.2.1 2026 Recommendations for Ute 3

At the Ute 3 station the AQD recommends the continuation of monitoring for NO2, O3, PM10,

PM2.5, visibility and meteorological parameters. In CY2026 and CY2027, the AQD recommends

using any additional funding for upgrading and replacement of the AQD’s aging meteorological

instruments, visibility monitor, and the zero air generator.

3.3.

Mobile Monitoring Station (MMS)

The Mobile Monitoring Station (MMS)

is located on the northeastern portion of

the Reservation near Lake Capote (Figure 1).

Figure 5 - Mobile Monitoring Station

The current location of the MMS meets

all siting criteria for an urban SLAMS for

measuring typical pollutant concentration in an area of high population density

area, as outlined by §§ 1.1.1.(b) &

1.2.(b)(4) of 40 CFR 58, Appendix D.

While the siting criteria for a SLAMS is

met at the current location, the station is

operated as a Special Purpose Monitoring

Station (SPMS) given its nature of being

mobile.

The MMS is located on the least populated area of the Reservation yet serves a population of

approximately 76,275 and an area of 15,204 mi2 (39,378 km2) for NO2 and an area of 4,754mi2

(12,313km2) with a population of approximately 44,621 for O3. Due to the scarcity of SLAMS in

western Colorado, the EPA’s NetAssess2025 app includes Pagosa Springs, Alamosa, some parts

of Northern New Mexico, and the Jicarilla Apache Nation Reservation within the areas served.

Demographics of this area were calculated in EPA’s NetAssess 2025 application and are included

in Appendix A

The Lake Capote MMS site (Figure 5) is located within a locked perimeter fence and the area is

regularly patrolled by Southern Ute Tribal Rangers as well as Tribal staff who live on the Lake

Capote recreation area grounds.

The purpose of the MMS has been to assess pre-oil and gas development and ambient air quality

conditions in the eastern portion of the Reservation and is likely to be affected by activities such

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14

as highway vehicle traffic and road construction. After completing an initial three-year background

monitoring campaign from 2017 to 2020, the MMS has remained “stationed” at its current location

at Lake Capote, but it could be moved in the future for special purpose monitoring projects or

source surveillance.

40 CFR 58.10(a)(5)(i) outlines the requirement for NO2 monitoring. The AQD utilizes a Teledyne

Model T200 NO/NO2/NOx analyzer following EPA FRM RFNA-1194-099 to monitor NO2, NOx,

and NO. The AQD monitors this pollutant to help estimate the influence of anthropogenic NO2

emissions in the formation of ozone on the Reservation as well as determining regulatory compliance with the NO2 NAAQS.

40 CFR 58.10(a)(9) outlines the requirement for O3 monitoring. The AQD utilizes a Teledyne

Model T400 Photometric O3 analyzer following EPA FRM EAOA-0992-087 to monitor for regulatory compliance with the O3 NAAQS.

The MMS continues to collect meteorological data for the following parameters: wind speed, wind

direction, ambient temperature, and humidity. All the meteorological sensors are located on an

aluminum tower affixed to the station roof. The data collected at the MMS is designated as nonregulatory for the purposes of NAAQS compliance determinations; however, the data collected at

MMS follows all quality assurance requirements for regulatory quality data collection. Criteria air

pollutants currently measured at the MMS are listed in Table 4. All measured criteria pollutant

values have remained below the current NAAQS.

Table 4. MMS CY2025 Measured Ambient Concentrations in Comparison to the NAAQS.

Instrument Type**

Reference

Method

Parameter

NAAQS

CY2025 *

Concentrations

Teledyne Model

53 ppb (annual)

2.71 ppb

RFNA-1194-099

T200 NO/NO2/NOx

and

NO2

analyzer and

100 ppb (1-hour)

15 ppb

EQOA-0880-047

Thermo 42i

Teledyne Model

EAOA-0992-087

T400 Photometric

and

O3

0.070 ppm (8-hour)

0.064 ppm

O3 Analyzer and

EQOA-0880-047

Thermo 49i

* CY25 data is included in this document because it is the most current full year of data collected at the

MMS. CY26 data is not complete and certified by the date of this review

** The Thermo Instruments were operated from January to May 19th before being replaced with Teledyne

Gas Analyzers

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3.3.1 2026 Recommendations for MMS

At the MMS the AQD recommends the continuation of monitoring for NO2, O3, and meteorological parameters. In CY2026 and CY2027, the AQD recommends using any additional funding for

upgrading and replacement of meteorological instruments, and the zero air generator.

4.0

Quality Assurance

Continuous Monitors

The AQD staff regularly assesses gaseous analyzer automated performance checks including:

Zero, Span, and Precision checks. Calibrations are performed as needed or once per quarter to

maintain accuracy, precision, and bias goals defined in the AQD’s Quality Assurance Project Plan

(QAPP). During these internal audits and checks, gas analyzers are challenged with NIST-certified

gas cylinders containing known concentrations of the applicable pollutant gases, diluted with zero

air using mass flow controllers. Every quarter, a third-party contractor performs system audits on

all the gaseous analyzers and PM instruments.

The EPA’s National Performance Audit Program (NPAP) is one of the major components in the

quality assurance of the Nation's air monitoring program. Annually the EPA performs an NPAP

audit at one of the ambient air monitoring stations. The most recent was conducted at Ute 1 station

on August 19, 2025. The NPAP audit for CY2026 has yet to be scheduled.

Particulate Monitors

Verification checks of the continuous particulate matter monitors have occurred monthly from

AQD staff and semi-annually by a 3rd party contractor and consist of calibrated flow rate checks,

as well as temperature, pressure, leak rate and flow rate verification checks.

Meteorological Monitors

Semi-annual calibrations and audit checks are performed by a third-party contractor on the meteorological equipment to determine proper alignment and operation of the sensors. The details and

minimum standards for this program are set out in the Code of Federal Regulations (Part 58 Ambient Air Quality Surveillance).

Quality Assurance Project Plan

A complete description of the quality assurance procedures completed for data collection at the

AQD’s three monitoring stations is contained in AQD’s Quality Assurance Project Plan (QAPP)

and the results are available from the AQD or through the national EPA AQS database.

EPA Technical System Audits

SUIT AIR QUALITY DIVISION – CY2026 NETWORK REVIEW

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The U.S. EPA Region VIII performs a Technical Systems audit on the Southern Ute Indian Tribe’s

Air Monitoring Network every three years. The most recent was in September 2025. AQD staff

conduct quality control checks at least once per week, and calibrations once every calendar quarter.

The details and minimum standards for this program are set out in the Code of Federal Regulations

(Part 58 Ambient Air Quality Surveillance).

5.0

Summary

The Southern Ute Reservation is located primarily within La Plata County with approximately

30% of the land located within Archuleta County.

Oil and gas is the predominant industry and contributor to ozone precursor emissions within the

Reservation boundaries. Due to the large quantity of oil and gas wells and facilities within the

Reservation boundaries, and the Tribe’s efforts to maintain good air quality on the Reservation

through administration of AQD’s Clean Air Act permitting programs, AQD plans to continue operating the three air monitoring stations.

6.0

Final Comments

The AQD continuously compares the ambient air quality data collected by the AQD monitoring

network to the NAAQS and local and regional air quality trends and uses this information to determine which pollutants should be monitoring on the Reservation. The AQD has determined that

all data pertaining to the AQD monitoring network for the 2025 calendar year meets all QA requirements for data submittal to AQS, the AQD 2026 QAPP, and tribal standard operating procedures, and that these findings will carry over into CY2027.

A draft of this document was made available to the public on June 3, 2026, at https://www.southernute-nsn.gov/government/departments/epd/public-comments/. Any comments pertaining to this

document should be sent to the following email address: airquality@southernute-nsn.gov.

For any questions on this document, you may contact any of the following AQD staff members:

Danny Powers

Southern Ute Indian Tribe

Air Quality Division Head

P.O. Box 737 MS# 84

Ignacio, Colorado 81137

970-563-2265

dpowers@southernute-nsn.gov

Andrew Switzer

Southern Ute Indian Tribe

Air Quality Program Manager

P.O. Box 737 MS# 84

Ignacio, Colorado 81137

970-563-2214

aswitzer@southernute-nsn.gov

SUIT AIR QUALITY DIVISION – CY2026 NETWORK REVIEW

Patricia Peña

Southern Ute Indian Tribe

Air Quality Specialist

P.O. Box 737 MS# 84

Ignacio, Colorado 81137

970-563-2221

ppena@southernute-nsn.gov

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