Public water system · MT0004563
ActiveGranite Park Water Association
At a glance
Granite Park Water Association (PWSID MT0004563) is an active community water system in Yellowstone County, Montana. It reports serving 250 people through 120 service connections. Its primary water source is groundwater, and EPA lists it as privately owned. 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
250
Service connections
120
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Granite Park Water Association compare with other water systems in Yellowstone County?
By EPA's size categories, Granite Park Water Association 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 0.1% 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 Granite Park Water Association 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 Granite Park Water Association?
EPA lists Granite Park Water Association as privately owned. 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. 97 of the 119 active systems in Yellowstone County (82%) are also privately owned.
Does Granite Park Water Association 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 2009 and January 2024. By type: 10 monitoring and reporting, 1 contaminant level above the legal limit and 1 public notice, recordkeeping or other. The contaminant or rule involved most often is Nitrate-Nitrite (3 of them). EPA lists 11 as resolved and 1 as archived. 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. Archived means the violation was not marked resolved but is more than five years past the end of the noncompliance period, so it no longer counts toward current compliance status.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2024-01-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Single Sample · code 01 | Nitrate-Nitritecode 1038 | Yes | Archived |
| 2023-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2023-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitrate-Nitritecode 1038 | No | Resolved |
| 2020-09-07 | Monitoring and reportingMonitoring, Source Water (GWR) · code 34 | E. colicode 3014 | No | Resolved |
| 2018-09-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Total trihalomethanes (TTHM)code 2950 | No | Resolved |
| 2018-09-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Haloacetic acids (HAA5)code 2456 | No | Resolved |
| 2016-11-03 | Monitoring and reportingMonitoring, Source Water (GWR) · code 34 | E. colicode 3014 | No | Resolved |
| 2015-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Di(2-ethylhexyl) phthalatecode 2039 | No | Resolved |
| 2014-12-30 | Monitoring and reportingLead Consumer Notice · code 66 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2013-07-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Chlorinecode 0999 | No | Resolved |
| 2009-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Gross alpha (excluding radon and uranium)code 4000 | No | Resolved |
| 2009-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitrate-Nitritecode 1038 | 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.
Granite Park Water Association: frequently asked questions
Who runs Granite Park Water Association?
Granite Park Water Association (PWSID MT0004563) is a community water system privately owned. It is regulated by the MT state drinking water program.
How many people does Granite Park Water Association serve?
Granite Park Water Association reports serving 250 people through 120 service connections in Yellowstone County, Montana.
Where does Granite Park Water Association 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 Granite Park Water Association 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 Granite Park Water Association'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 Granite Park Water Association's water quality report?
As a community water system, Granite Park Water Association 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, “Granite Park Water Association, PWSID MT0004563, Montana”, https://aquacensus.com/water-systems/montana/granite-park-water-association-mt0004563 (data as of October 1, 2026).