Public water system · MT0000235
ActiveHardin City of
At a glance
City of Hardin (PWSID MT0000235) is an active community water system in Big Horn County, Montana. It reports serving 3,500 people through 1,307 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, none is health-based, and the most recent began in April 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
3,500
Service connections
1,307
Primary source
SW
Surface water
System type
CWS
Community water system
System record
How does City of Hardin compare with other water systems in Big Horn County?
By EPA's size categories, City of Hardin is a medium system (3,301 to 10,000 people). Big Horn County has 23 active public water systems, and City of Hardin is the largest of them by population served. Its population served is about 7.8 times the county average of 449 people per system, and accounts for 34% 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 community water system reports serving 6,703 people, so City of Hardin is about half of 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 Hardin?
EPA lists City of Hardin 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 23 active systems in Big Horn County (17%) are also owned by a local government.
Does City of Hardin have drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in April 2025. The violations listed here began between July 2004 and April 2025. By type: 8 monitoring and reporting and 4 public notice, recordkeeping or other. The contaminant or rule involved most often is Consumer Confidence 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 |
|---|---|---|---|---|
| 2025-04-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2025-04-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2020-09-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2020-09-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2014-01-01 | Monitoring and reportingLead Consumer Notice · code 66 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2013-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2012-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2010-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2006-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2004-07-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Carbon, totalcode 2920 | No | Resolved |
| 2004-07-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Carbon, totalcode 2920 | 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 Hardin: frequently asked questions
Who runs City of Hardin?
City of Hardin (PWSID MT0000235) 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 Hardin serve?
City of Hardin reports serving 3,500 people through 1,307 service connections in Big Horn County, Montana.
Where does City of Hardin 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 Hardin 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 April 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 City of Hardin'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 April 2025. 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 Hardin's water quality report?
As a community water system, City of Hardin 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 Big Horn County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| 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 |
| Tongue River Campers Point | Big Horn | 305 | 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, “Hardin City of, PWSID MT0000235, Montana”, https://aquacensus.com/water-systems/montana/hardin-city-of-mt0000235 (data as of October 1, 2026).