Public water system · MT0000180
ActiveColstrip City of
At a glance
City of Colstrip (PWSID MT0000180) is an active community water system in Rosebud County, Montana. It reports serving 2,350 people through 913 service connections. Its primary water source is surface water, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, 2 are health-based, and the most recent began in July 2024.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
2,350
Service connections
913
Primary source
SW
Surface water
System type
CWS
Community water system
System record
How does City of Colstrip compare with other water systems in Rosebud County?
By EPA's size categories, City of Colstrip is a small system (501 to 3,300 people). Rosebud County has 15 active public water systems, and City of Colstrip is the largest of them by population served. Its population served is about 4.8 times the county average of 494 people per system, and accounts for 32% of the 7,415 people reported by systems filed under the county. Across Montana, the 2,378 active systems average 489 people each. Nationally, the average active community water system reports serving 6,703 people, so City of Colstrip is about 65% below that figure.
What does “community water system” mean?
A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. Montana has 853 active community water systems, 36% of the state's 2,378 active systems. Surface water means the system draws its water from rivers, lakes, streams or reservoirs. 60 Montana systems (2.5%) list surface water as their primary source.
Who owns and regulates City of Colstrip?
EPA lists City of Colstrip as owned by a local government. 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. 4 of the 15 active systems in Rosebud County (27%) are also owned by a local government.
Does City of Colstrip have drinking water violations?
Of the 12 most recent violations in EPA's records, 2 are health-based, and the most recent began in July 2024. The violations listed here began between July 2004 and July 2024. By type: 9 monitoring and reporting, 1 contaminant level above the legal limit, 1 required treatment not met and 1 monitoring. The contaminant or rule involved most often is Surface Water Treatment Rule (4 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 |
|---|---|---|---|---|
| 2024-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02 | Total trihalomethanes (TTHM)code 2950 | Yes | Resolved |
| 2024-07-01 | Required treatment not metTreatment Technique (SWTR and GWR) · code 41 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 2024-01-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Filter) · code 36 | Surface Water Treatment Rulecode 0200 | No | Resolved |
| 2024-01-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Filter) · code 36 | Surface Water Treatment Rulecode 0200 | No | Resolved |
| 2024-01-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Filter) · code 36 | Surface Water Treatment Rulecode 0200 | No | Resolved |
| 2023-07-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2023-07-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2022-05-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2011-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Asbestoscode 1094 | No | Resolved |
| 2008-08-01 | Monitoring and reportingMonitoring, Repeat Minor (TCR) · code 26 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2007-09-01 | Monitoring and reportingMonitoring, Routine Major (TCR) · code 23 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2004-07-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Carbon, totalcode 2920 | 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.
City of Colstrip: frequently asked questions
Who runs City of Colstrip?
City of Colstrip (PWSID MT0000180) is a community water system owned by a local government. It is regulated by the MT state drinking water program.
How many people does City of Colstrip serve?
City of Colstrip reports serving 2,350 people through 913 service connections in Rosebud County, Montana.
Where does City of Colstrip get its water?
EPA SDWIS lists this system's primary water source as surface water. Surface water means the system draws its water from rivers, lakes, streams or reservoirs.
Does City of Colstrip have any drinking water violations?
Of the 12 most recent violations in EPA's records, 2 are health-based, and the most recent began in July 2024. 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 City of Colstrip'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, 2 are health-based, and the most recent began in July 2024. For current results, consult the system's annual water quality report, EPA ECHO, or the MT state drinking water program.
Where can I find City of Colstrip's water quality report?
As a community water system, City of Colstrip must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1 each year, covering the previous calendar year. The system can provide a copy on request.
Other water systems in Rosebud County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Forsyth City of | Rosebud | 2,260 | Community | Surface water |
| St Labre Indian School | Rosebud | 650 | Community | Groundwater |
| East Bound Hathaway Rest Area | Rosebud | 600 | Transient non-community | Groundwater |
| Wb Hathaway Rest Area | Rosebud | 600 | Transient non-community | Groundwater |
| Ashland Water and Sewer Dist | Rosebud | 400 | Community | Groundwater |
| Western Energy Company | Rosebud | 200 | Non-transient non-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, “Colstrip City of, PWSID MT0000180, Montana”, https://aquacensus.com/water-systems/montana/colstrip-city-of-mt0000180 (data as of October 1, 2026).