Public water system · MT0000953
ActiveEast Decker Coal Mine
At a glance
East Decker Coal Mine (PWSID MT0000953) is an active non-transient non-community water system in Big Horn County, Montana. It reports serving 28 people through 3 service connections. Its primary water source is groundwater, and EPA lists it as privately owned. Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in June 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
28
Service connections
3
Primary source
GW
Groundwater
System type
NTNCWS
Non-transient non-community water system
System record
How does East Decker Coal Mine compare with other water systems in Big Horn County?
By EPA's size categories, East Decker Coal Mine is a very small system (500 people or fewer). Big Horn County has 23 active public water systems. Its population served is well below the county average of 449 people per system, and accounts for 0.3% of the 10,335 people reported by systems filed under the county. Across Montana, the 2,378 active systems average 489 people each. Nationally, the average active non-transient non-community water system reports serving 430 people, so East Decker Coal Mine is well below that figure.
What does “non-transient non-community water system” mean?
A non-transient non-community water system regularly serves at least 25 of the same people for more than six months a year, but not where they live. Schools, factories, office buildings and hospitals with their own supply are typical examples. Montana has 319 active non-transient non-community water systems, 13% of the state's 2,378 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 1,994 Montana systems (84%) list groundwater as their primary source.
Who owns and regulates East Decker Coal Mine?
EPA lists East Decker Coal Mine as privately owned. The MT state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 11 of the 23 active systems in Big Horn County (48%) are also privately owned.
Does East Decker Coal Mine have drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in June 2025. The violations listed here began between January 1996 and June 2025. By type: 11 monitoring and reporting and 1 monitoring. The contaminant or rule involved most often is Groundwater Rule (3 of them). EPA lists 12 as resolved. Resolved means at least one resolving action is on record: the system returned to compliance, the rule no longer applies, or no further action was needed.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2025-06-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Unfilt/GWR) · code 31 | Groundwater Rulecode 0700 | No | Resolved |
| 2025-03-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Unfilt/GWR) · code 31 | Groundwater Rulecode 0700 | No | Resolved |
| 2023-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2023-07-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Unfilt/GWR) · code 31 | Groundwater Rulecode 0700 | No | Resolved |
| 2021-10-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2010-01-01 | Monitoring and reportingLead Consumer Notice · code 66 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2004-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2004-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 1996-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Aldicarb sulfonecode 2044 | No | Resolved |
| 1996-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Aldicarbcode 2047 | No | Resolved |
| 1996-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Oxamylcode 2036 | No | Resolved |
| 1996-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Carbofurancode 2046 | No | Resolved |
The 12 most recent violations in EPA's records, newest first.Labels and codes come from EPA's SDWIS reference tables. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found. "Health-based" marks violations of a legal limit or required treatment.
East Decker Coal Mine: frequently asked questions
Who runs East Decker Coal Mine?
East Decker Coal Mine (PWSID MT0000953) is a non-transient non-community water system privately owned. It is regulated by the MT state drinking water program.
How many people does East Decker Coal Mine serve?
East Decker Coal Mine reports serving 28 people through 3 service connections in Big Horn County, Montana.
Where does East Decker Coal Mine get its water?
EPA SDWIS lists this system's primary water source as groundwater. Groundwater means the system draws its water from wells or springs fed by underground aquifers.
Does East Decker Coal Mine have any drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in June 2025. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found.
Is East Decker Coal Mine's water safe to drink?
AquaCensus shows EPA compliance records, not current water test results, so it cannot say whether the water is safe at a given moment. Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in June 2025. For current results, consult EPA ECHO, or the MT state drinking water program.
Where can I find East Decker Coal Mine's water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. East Decker Coal Mine is a non-transient non-community water system, so it is not required to publish one; like every public water system, it must notify the people it serves about violations under EPA's public notification rules.
Other water systems in Big Horn County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Hardin City of | Big Horn | 3,500 | Community | Surface water |
| Little Bighorn Battlefield Nm | Big Horn | 2,020 | Non-transient non-community | Groundwater |
| Hardin Eastbound Rest Area | Big Horn | 877 | Transient non-community | Groundwater |
| Hardin Westbound Rest Area | Big Horn | 715 | Transient non-community | Groundwater |
| Lodge Grass Town of | Big Horn | 480 | Community | Groundwater |
| Fort Smith Water and Sewer District | Big Horn | 450 | Community | Groundwater |
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About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “East Decker Coal Mine, PWSID MT0000953, Montana”, https://aquacensus.com/water-systems/montana/east-decker-coal-mine-mt0000953 (data as of October 1, 2026).