Public water system · MT0000158
ActiveBoulder City of
At a glance
City of Boulder (PWSID MT0000158) is an active community water system in Jefferson County, Montana. It reports serving 1,400 people through 563 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in January 2024.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
1,400
Service connections
563
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does City of Boulder compare with other water systems in Jefferson County?
By EPA's size categories, City of Boulder is a small system (501 to 3,300 people). Jefferson County has 41 active public water systems, and City of Boulder is the 2nd-largest of them by population served. Its population served is about 5.8 times the county average of 241 people per system, and accounts for 14% of the 9,886 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 Boulder is well 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. 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 City of Boulder?
EPA lists City of Boulder 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 41 active systems in Jefferson County (9.8%) are also owned by a local government.
Does City of Boulder have drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in January 2024. The violations listed here began between January 2011 and January 2024. By type: 10 monitoring and reporting, 1 required treatment not met and 1 monitoring. The contaminant or rule involved most often is Total trihalomethanes (TTHM) (2 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 |
|---|---|---|---|---|
| 2024-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2024-01-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2022-07-01 | Required treatment not metFailure to Filter (SWTR) · code 42 | Surface Water Treatment Rulecode 0200 | Yes | Resolved |
| 2018-09-01 | MonitoringMonitoring, Routine (RTCR) · code 3A | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 2014-09-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2014-09-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2011-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Seleniumcode 1045 | No | Resolved |
| 2011-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nickelcode 1036 | No | Resolved |
| 2011-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Mercurycode 1035 | No | Resolved |
| 2011-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Thalliumcode 1085 | No | Resolved |
| 2011-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Fluoridecode 1025 | No | Resolved |
| 2011-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Berylliumcode 1075 | 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 Boulder: frequently asked questions
Who runs City of Boulder?
City of Boulder (PWSID MT0000158) 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 Boulder serve?
City of Boulder reports serving 1,400 people through 563 service connections in Jefferson County, Montana.
Where does City of Boulder 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 City of Boulder have any drinking water violations?
Of the 12 most recent violations in EPA's records, one is health-based, and the most recent began in January 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 Boulder'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, one is health-based, and the most recent began in January 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 Boulder's water quality report?
As a community water system, City of Boulder 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 Jefferson County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Whitehall Town of | Jefferson | 1,500 | Community | Groundwater |
| Jefferson Hills Wua | Jefferson | 780 | Community | Groundwater |
| Lewis and Clark Caverns Visitor Center | Jefferson | 615 | Transient non-community | Groundwater under influence of surface water |
| Jefferson City South Rest Stop | Jefferson | 600 | Transient non-community | Groundwater |
| Montana City School Dist 27 | Jefferson | 534 | Non-transient non-community | Groundwater |
| Saddle Mountain Corp Clancy | Jefferson | 350 | 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, “Boulder City of, PWSID MT0000158, Montana”, https://aquacensus.com/water-systems/montana/boulder-city-of-mt0000158 (data as of October 1, 2026).