Public water system · 083090031
ActiveSt Ignatius (Mission) So.Side
At a glance
St Ignatius (Mission) So.Side (PWSID 083090031) is an active community water system in Montana. It reports serving 356 people through 148 service connections. Its primary water source is groundwater, and EPA lists it as Native American-owned. Of the 12 most recent violations in EPA's records, 5 are health-based, and the most recent began in December 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
356
Service connections
148
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does St Ignatius (Mission) So.Side compare with other water systems in Montana?
By EPA's size categories, St Ignatius (Mission) So.Side is a very small system (500 people or fewer). Across Montana, the 2,378 active systems average 489 people each. Nationally, the average active community water system reports serving 6,703 people, so St Ignatius (Mission) So.Side 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 St Ignatius (Mission) So.Side?
EPA lists St Ignatius (Mission) So.Side as Native American-owned. The EPA Region 08 is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act.
Does St Ignatius (Mission) So.Side have drinking water violations?
Of the 12 most recent violations in EPA's records, 5 are health-based, and the most recent began in December 2025. The violations listed here began between June 1976 and December 2025. By type: 7 monitoring and reporting and 5 contaminant level above the legal limit. The contaminant or rule involved most often is Total coliform bacteria (TCR) (9 of them). EPA lists 9 as archived and 3 as resolved. 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. 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 |
|---|---|---|---|---|
| 2025-12-01 | Monitoring and reportingMonitoring and Reporting (DBP) · code 27 | Chlorinecode 0999 | No | Resolved |
| 2023-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
| 2008-05-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1992-09-01 | Monitoring and reportingMonitoring, Repeat Minor (TCR) · code 26 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1992-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1992-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1992-09-01 | Monitoring and reportingMonitoring, Repeat Minor (TCR) · code 26 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1992-09-01 | Monitoring and reportingMonitoring, Repeat Minor (TCR) · code 26 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1992-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1992-09-01 | Monitoring and reportingMonitoring, Repeat Minor (TCR) · code 26 | Total coliform bacteria (TCR)code 3100 | No | Archived |
| 1992-09-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Archived |
| 1976-06-01 | Monitoring and reportingMonitoring, Regular · code 03 | Combined Radium (-226 and -228)code 4010 | No | Archived |
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.
St Ignatius (Mission) So.Side: frequently asked questions
Who runs St Ignatius (Mission) So.Side?
St Ignatius (Mission) So.Side (PWSID 083090031) is a community water system Native American-owned. It is regulated by the EPA Region 08.
How many people does St Ignatius (Mission) So.Side serve?
St Ignatius (Mission) So.Side reports serving 356 people through 148 service connections in Montana.
Where does St Ignatius (Mission) So.Side 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 St Ignatius (Mission) So.Side have any drinking water violations?
Of the 12 most recent violations in EPA's records, 5 are health-based, and the most recent began in December 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 St Ignatius (Mission) So.Side'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, 5 are health-based, and the most recent began in December 2025. For current results, consult the system's annual water quality report, EPA ECHO, or the EPA Region 08.
Where can I find St Ignatius (Mission) So.Side's water quality report?
As a community water system, St Ignatius (Mission) So.Side 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 Montana
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Billings City of | Yellowstone | 114,000 | Community | Surface water |
| Missoula Water | Missoula | 68,200 | Community | Groundwater |
| Great Falls City of | Cascade | 60,000 | Community | Surface water |
| Bozeman City of | Gallatin | 56,000 | Community | Surface water |
| Butte Silverbow Water Dept | Silver Bow | 33,000 | Community | Surface water |
| Helena Water System | Lewis and Clark | 32,091 | Community | 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, “St Ignatius (Mission) So.Side, PWSID 083090031, Montana”, https://aquacensus.com/water-systems/montana/st-ignatius-mission-so-side-083090031 (data as of October 1, 2026).