Public water system · MT0042406
ActiveThompson Falls Mt State Park
At a glance
Thompson Falls Mt State Park (PWSID MT0042406) is an active transient non-community water system in Sanders County, Montana. It reports serving 42 people through 15 service connections. Its primary water source is groundwater, and EPA lists it as owned by a state government. EPA's records list 3 violations for this system; 2 are health-based, and the most recent began in May 2020.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
42
Service connections
15
Primary source
GW
Groundwater
System type
TNCWS
Transient non-community water system
System record
How does Thompson Falls Mt State Park compare with other water systems in Sanders County?
By EPA's size categories, Thompson Falls Mt State Park is a very small system (500 people or fewer). Sanders County has 44 active public water systems. Its population served is well below the county average of 209 people per system, and accounts for 0.5% of the 9,212 people reported by systems filed under the county. Across Montana, the 2,378 active systems average 489 people each. Nationally, the average active transient non-community water system reports serving 144 people, so Thompson Falls Mt State Park is well below that figure.
What does “transient non-community water system” mean?
A transient non-community water system serves places where people do not stay long, such as gas stations and campgrounds, and regularly serves at least 25 people a day for at least 60 days a year. Montana has 1,206 active transient non-community water systems, 51% 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 Thompson Falls Mt State Park?
EPA lists Thompson Falls Mt State Park as owned by a state 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. 1 of the 44 active systems in Sanders County (2.3%) are also owned by a state government.
Does Thompson Falls Mt State Park have drinking water violations?
EPA's records list 3 violations for this system; 2 are health-based, and the most recent began in May 2020. The violations listed here began between August 1994 and May 2020. By type: 2 contaminant level above the legal limit and 1 reporting. The contaminant or rule involved most often is Total coliform bacteria (TCR) (2 of them). EPA lists 3 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 |
|---|---|---|---|---|
| 2020-05-02 | ReportingReport Startup Procedures Cert Form (RTCR) · code 4C | Revised Total Coliform Rulecode 8000 | No | Resolved |
| 1998-07-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1994-08-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
All 3 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.
Thompson Falls Mt State Park: frequently asked questions
Who runs Thompson Falls Mt State Park?
Thompson Falls Mt State Park (PWSID MT0042406) is a transient non-community water system owned by a state government. It is regulated by the MT state drinking water program.
How many people does Thompson Falls Mt State Park serve?
Thompson Falls Mt State Park reports serving 42 people through 15 service connections in Sanders County, Montana.
Where does Thompson Falls Mt State Park 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 Thompson Falls Mt State Park have any drinking water violations?
EPA's records list 3 violations for this system; 2 are health-based, and the most recent began in May 2020. 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 Thompson Falls Mt State Park'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. EPA's records list 3 violations for this system; 2 are health-based, and the most recent began in May 2020. For current results, consult EPA ECHO, or the MT state drinking water program.
Where can I find Thompson Falls Mt State Park's water quality report?
The annual Consumer Confidence Report requirement applies to community water systems. Thompson Falls Mt State Park is a 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 Sanders County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Thompson Falls City of | Sanders | 1,950 | Community | Groundwater |
| Plains Town of | Sanders | 1,700 | Community | Groundwater |
| Hot Springs Municipal Water | Sanders | 600 | Community | Groundwater |
| One Stop | Sanders | 500 | Transient non-community | Groundwater |
| Sanders County Harvest Foods | Sanders | 445 | Non-transient non-community | Groundwater |
| Water Service Inc. Trout Creek | Sanders | 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, “Thompson Falls Mt State Park, PWSID MT0042406, Montana”, https://aquacensus.com/water-systems/montana/thompson-falls-mt-state-park-mt0042406 (data as of October 1, 2026).