Non-Transient Non-Community Water System · PWS MT0000953
East Decker Coal Mine
Decker, Montana 59025 - drinking water served from groundwater sources to 28 people, tracked in EPA SDWIS and UCMR5.
- 28
- People served
- 31
- EPA violations
- 0
- Health-based
- Untested
- UCMR5 result
The verdict
EPA records 31 drinking-water violations at East Decker Coal Mine - below the Montana per-system average.
- 31
- Total EPA violations on record
- 0%
- Health-based (MCL / treatment failure)
- 28
- People served by this system
- N/A
- PFAS compounds detected (UCMR5)
Water Quality Snapshot: East Decker Coal Mine
East Decker Coal Mine is a private-owned non-transient non-community water system that delivers drinking water to 28 residents in Decker, Montana (Big Horn County) through 3 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 31 total violations for this system , of which 0 (0%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 31 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 Groundwater Rule, recorded in 11 violations (MR). 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%).
East Decker Coal Mine's 31 violations sit below 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.
System Details
- System Type
- Non-Transient Non-Community
- Owner Type
- Private
- Connections
- 3
- County
- Big Horn
- School/Daycare
- No
- MCL Violations
- 0
- Monitoring Violations
- 31
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Groundwater Rule | MR | 11 | 2025 |
| Lead and Copper Rule | MR | 5 | 2023 |
| TTHM | MR | 3 | 2004 |
| Revised Total Coliform Rule | MON | 3 | 2021 |
| Total Haloacetic Acids (HAA5) | MR | 3 | 2004 |
| OXAMYL | MR | 1 | 1996 |
| Nitrate | MR | 1 | 1981 |
| Carbofuran | MR | 1 | 1996 |
| Aldicarb sulfoxide | MR | 1 | 1996 |
| Aldicarb | MR | 1 | 1996 |
| Aldicarb sulfone | MR | 1 | 1996 |
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 East Decker Coal Mine.
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 MT0000953 on SDWISSource: EPA SDWIS Federal Reports Search
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 SDWISViolation 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 | Groundwater Rule | MR | 11 | SDWIS / MT0000953 / 0700 |
| 2023 | Lead and Copper Rule | MR | 5 | SDWIS / MT0000953 / 5000 |
| 2021 | Revised Total Coliform Rule | MON | 3 | SDWIS / MT0000953 / 8000 |
| 2004 | TTHM | MR | 3 | SDWIS / MT0000953 / 2950 |
| 2004 | Total Haloacetic Acids (HAA5) | MR | 3 | SDWIS / MT0000953 / 2456 |
| 1996 | OXAMYL | MR | 1 | SDWIS / MT0000953 / 2036 |
| 1996 | Carbofuran | MR | 1 | SDWIS / MT0000953 / 2046 |
| 1996 | Aldicarb sulfoxide | MR | 1 | SDWIS / MT0000953 / 2043 |
| 1996 | Aldicarb | MR | 1 | SDWIS / MT0000953 / 2047 |
| 1996 | Aldicarb sulfone | MR | 1 | SDWIS / MT0000953 / 2044 |
| 1981 | Nitrate | MR | 1 | SDWIS / MT0000953 / 1040 |
How East Decker Coal Mine Compares
Cross-reference this system's record against state averages and the federal MCL framework for context.
| Metric | East Decker Coal Mine | Montana avg | Federal benchmark |
|---|---|---|---|
| Total violations | 31 | 131.4 | SDWA compliance, any non-zero count is a recorded breach |
| Health-based violations | 0 | 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 | 28 | 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 East Decker Coal Mine water safe to drink? ▼
How many people does East Decker Coal Mine serve? ▼
What type of violations does East Decker Coal Mine have? ▼
Has PFAS been detected in East Decker Coal Mine water? ▼
What water source does East Decker Coal Mine use? ▼
Where does this data come from? ▼
Read our methodology - how this data is sourced, computed, and verified.
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.