Public water system · MT0003374
ActiveHidden Lake Yellowstone County W and S D
At a glance
Hidden Lake Yellowstone County W and S D (PWSID MT0003374) is an active community water system in Yellowstone County, Montana. It reports serving 350 people through 113 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, none is health-based, and the most recent began in November 2023.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
350
Service connections
113
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Hidden Lake Yellowstone County W and S D compare with other water systems in Yellowstone County?
By EPA's size categories, Hidden Lake Yellowstone County W and S D is a very small system (500 people or fewer). Yellowstone County has 119 active public water systems. Its population served is well below the county average of 1,422 people per system, and accounts for 0.2% of the 169,240 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 Hidden Lake Yellowstone County W and S D 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 Hidden Lake Yellowstone County W and S D?
EPA lists Hidden Lake Yellowstone County W and S D 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. 15 of the 119 active systems in Yellowstone County (13%) are also owned by a local government.
Does Hidden Lake Yellowstone County W and S D have drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in November 2023. The violations listed here began between January 2020 and November 2023. By type: 12 monitoring and reporting. 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 |
|---|---|---|---|---|
| 2023-11-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Unfilt/GWR) · code 31 | Groundwater Rulecode 0700 | No | Resolved |
| 2021-08-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Unfilt/GWR) · code 31 | Groundwater Rulecode 0700 | No | Resolved |
| 2020-04-01 | Monitoring and reportingMonitoring of Treatment (SWTR-Unfilt/GWR) · code 31 | Groundwater Rulecode 0700 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,1,2-Trichloroethanecode 2985 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,2-Dichloroethanecode 2980 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Carbon tetrachloridecode 2982 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,2-Dichloropropanecode 2983 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,2,4-Trichlorobenzenecode 2378 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | cis-1,2-Dichloroethylenecode 2380 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | p-Dichlorobenzenecode 2969 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | o-Dichlorobenzenecode 2968 | No | Resolved |
| 2020-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Vinyl chloridecode 2976 | 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.
Hidden Lake Yellowstone County W and S D: frequently asked questions
Who runs Hidden Lake Yellowstone County W and S D?
Hidden Lake Yellowstone County W and S D (PWSID MT0003374) is a community water system owned by a local government. It is regulated by the MT state drinking water program.
How many people does Hidden Lake Yellowstone County W and S D serve?
Hidden Lake Yellowstone County W and S D reports serving 350 people through 113 service connections in Yellowstone County, Montana.
Where does Hidden Lake Yellowstone County W and S D 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 Hidden Lake Yellowstone County W and S D 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 November 2023. 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 Hidden Lake Yellowstone County W and S D'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 November 2023. For current results, consult the system's annual water quality report, EPA ECHO, or the MT state drinking water program.
Where can I find Hidden Lake Yellowstone County W and S D's water quality report?
As a community water system, Hidden Lake Yellowstone County W and S D 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 Yellowstone County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Billings City of | Yellowstone | 114,000 | Community | Surface water |
| Billings Heights Co Water Dist of | Yellowstone | 12,000 | Community | Purchased surface water |
| Laurel Municipal Water System | Yellowstone | 6,339 | Community | Surface water |
| Lockwood Water and Sewer District | Yellowstone | 5,900 | Community | Surface water |
| Rocky Mountain College | Yellowstone | 5,700 | Non-transient non-community | Purchased surface water |
| Montana State University Billings | Yellowstone | 2,999 | Non-transient non-community | Purchased surface water |
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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, “Hidden Lake Yellowstone County W and S D, PWSID MT0003374, Montana”, https://aquacensus.com/water-systems/montana/hidden-lake-yellowstone-county-w-and-s-d-mt0003374 (data as of October 1, 2026).