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Community Water System · PWS MT0000187

Cooke City Water District

Cooke City, Montana 59020 - drinking water served from groundwater sources to 300 people, tracked in EPA SDWIS and UCMR5.

300
People served
941
EPA violations
43
Health-based
Untested
UCMR5 result

The verdict

EPA records 941 drinking-water violations at Cooke City Water District, 5% of them health-based - above the Montana per-system average.

941
Total EPA violations on record
5%
Health-based (MCL / treatment failure)
300
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Cooke City Water District

Cooke City Water District is a local-owned community water system that delivers drinking water to 300 residents in Cooke City, Montana (Park County) through 98 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 941 total violations for this system , of which 43 (5%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 875 monitoring and reporting violations are on file. The most recent violation on record dates to 2025.

The most frequently cited contaminant at this system is Coliform (TCR), recorded in 35 violations (MCL, health-based). This system has not yet been sampled under EPA's UCMR5 PFAS monitoring program, so no PFAS detection data is available here.

Across Montana, EPA tracks 2,263 public water systems serving 1,112,267 people, with 297,270 cumulative violations and 25,922 health-based violations on record. About 95% of systems in the state carry at least one violation, and state-wide the average per system is 131.4 violations. Statewide, 28 of 45 UCMR5-tested systems have reported PFAS detections (62.2%).

Cooke City Water District's 941 violations sit above the Montana average.

All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.

Population Served
300
Total Violations
941
Health-Based Violations
43
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Local
Connections
98
County
Park
School/Daycare
No
MCL Violations
35
Monitoring Violations
875
Treatment Tech Violations
8

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Coliform (TCR) MCL 35 2009
DICHLOROMETHANE MR 27 2020
1,2-Dichloroethane MR 27 2020
1,1,1-Trichloroethane MR 27 2020
1,2-Dichloropropane MR 27 2020
Tetrachloroethylene MR 27 2020
Benzene MR 27 2020
Toluene MR 27 2020
Styrene MR 27 2020
Xylenes, Total MR 27 2020
o-Dichlorobenzene MR 27 2020
p-Dichlorobenzene MR 27 2020
1,1-Dichloroethylene MR 27 2020
Trichloroethylene MR 27 2020
CHLOROBENZENE MR 27 2020
Ethylbenzene MR 27 2020
1,2,4-Trichlorobenzene MR 27 2020
cis-1,2-Dichloroethylene MR 27 2020
Vinyl chloride MR 27 2020
trans-1,2-Dichloroethylene MR 27 2020
Carbon tetrachloride MR 27 2020
1,1,2-Trichloroethane MR 27 2020
Revised Total Coliform Rule MON 25 2023
Consumer Confidence Rule Other 20 2025
Coliform (TCR) MR 19 2014
Lead and Copper Rule MR 16 2014
Di(2-ethylhexyl) phthalate MR 13 2021
Nitrate-Nitrite MR 10 2020
Thallium, Total MR 9 2005
Nickel MR 9 2005

Verify This Water System

The figures above are aggregated from EPA's public databases. To verify the underlying records, or to file a complaint, request a Consumer Confidence Report, or check current monitoring status, go directly to the federal and state regulators that enforce the Safe Drinking Water Act for Cooke City Water District.

Federal Source of Truth

EPA SDWIS, Federal Reports

EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:

View PWS ID MT0000187 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

Montana Drinking Water Authority

Montana's primacy agency administers the Safe Drinking Water Act locally. Search EPA SDWIS for the current state contact, or use the state's public health or environment department portal.

Find MT regulator via EPA SDWIS

Violation Timeline

Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.

Year (latest) Contaminant Category Count EPA Record
2025 Consumer Confidence Rule Other 20 SDWIS / MT0000187 / 7000
2023 Revised Total Coliform Rule MON 25 SDWIS / MT0000187 / 8000
2021 Di(2-ethylhexyl) phthalate MR 13 SDWIS / MT0000187 / 2039
2020 DICHLOROMETHANE MR 27 SDWIS / MT0000187 / 2964
2020 1,2-Dichloroethane MR 27 SDWIS / MT0000187 / 2980
2020 1,1,1-Trichloroethane MR 27 SDWIS / MT0000187 / 2981
2020 1,2-Dichloropropane MR 27 SDWIS / MT0000187 / 2983
2020 Tetrachloroethylene MR 27 SDWIS / MT0000187 / 2987
2020 Benzene MR 27 SDWIS / MT0000187 / 2990
2020 Toluene MR 27 SDWIS / MT0000187 / 2991
2020 Styrene MR 27 SDWIS / MT0000187 / 2996
2020 Xylenes, Total MR 27 SDWIS / MT0000187 / 2955
2020 o-Dichlorobenzene MR 27 SDWIS / MT0000187 / 2968
2020 p-Dichlorobenzene MR 27 SDWIS / MT0000187 / 2969
2020 1,1-Dichloroethylene MR 27 SDWIS / MT0000187 / 2977

How Cooke City Water District Compares

Cross-reference this system's record against state averages and the federal MCL framework for context.

Metric Cooke City Water District Montana avg Federal benchmark
Total violations 941 131.4 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 43 11.5 Indicates a contaminant exceeded a federal MCL
PFAS detection None 62.2% EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 300 492 Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 2,263 regulated public water systems in Montana.

Federal MCL reference, Safe Drinking Water Act thresholds ▼
Contaminant Federal MCL / Action Level Note
Lead 0 mg/L (Action Level: 0.015 mg/L) Lead and Copper Rule treatment technique
Arsenic 0.010 mg/L (10 ppb) Health-based MCL since 2006
Total Coliform Treatment technique (RTCR) Indicator organism, monitoring trigger
PFOA / PFOS (PFAS) 4.0 ppt each (final 2024 rule) Compliance deadline 2029 (EPA proposed extending to 2031, not yet final as of May 2026)
Nitrate (as N) 10 mg/L Acute health risk for infants

Frequently Asked Questions

Is Cooke City Water District water safe to drink? ▼
Cooke City Water District (PWS ID: MT0000187) has 941 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 300 people using Groundwater sources.
How many people does Cooke City Water District serve? ▼
Cooke City Water District serves 300 people in Cooke City, Montana. It is a Local-owned system using Groundwater water sources with 98 service connections.
What type of violations does Cooke City Water District have? ▼
Cooke City Water District has 941 total violations: 43 health-based violations (MCL exceedances or treatment failures), 875 monitoring/reporting violations, and 8 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Cooke City Water District water? ▼
No PFAS testing data is available for Cooke City Water District under the EPA's UCMR5 monitoring program.
What water source does Cooke City Water District use? ▼
Cooke City Water District uses Groundwater as its primary water source. It is classified as a Community Water System (CWS), serving residential populations year-round.
Where does this data come from? ▼
All data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS tracks compliance for all public water systems regulated under the Safe Drinking Water Act.
Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025. This data is provided for informational purposes only.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This system's figures are rendered directly from EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.