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Community Water System · PWS MT0000582

Angel Island Subdivision

Troy, Montana 59935 - drinking water served from groundwater sources to 150 people, tracked in EPA SDWIS and UCMR5.

150
People served
17
EPA violations
0
Health-based
Untested
UCMR5 result

The verdict

EPA records 17 drinking-water violations at Angel Island Subdivision - below the Montana per-system average.

17
Total EPA violations on record
0%
Health-based (MCL / treatment failure)
150
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Angel Island Subdivision

Angel Island Subdivision is a private-owned community water system that delivers drinking water to 150 residents in Troy, Montana (Lincoln County) through 184 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 17 total violations for this system , of which 0 (0%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 16 monitoring and reporting violations are on file. The most recent violation on record dates to 2003.

The most frequently cited contaminant at this system is Beryllium, Total, recorded in 4 violations (MR). This system has not yet been sampled under EPA's UCMR5 PFAS monitoring program, so no PFAS detection data is available here.

Across Montana, EPA tracks 2,263 public water systems serving 1,112,267 people, with 297,270 cumulative violations and 25,922 health-based violations on record. About 95% of systems in the state carry at least one violation, and state-wide the average per system is 131.4 violations. Statewide, 28 of 45 UCMR5-tested systems have reported PFAS detections (62.2%).

Angel Island Subdivision's 17 violations sit below the Montana average.

All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.

Population Served
150
Total Violations
17
Health-Based Violations
0
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Private
Connections
184
County
Lincoln
School/Daycare
No
MCL Violations
0
Monitoring Violations
16
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Beryllium, Total MR 4 1999
Coliform (TCR) MR 3 2003
Nitrate MR 2 1996
Chromium MR 1 1981
Selenium MR 1 1981
Fluoride MR 1 1981
Mercury MR 1 1981
Cadmium MR 1 1981
Barium MR 1 1981
Arsenic MR 1 1981

Verify This Water System

The figures above are aggregated from EPA's public databases. To verify the underlying records, or to file a complaint, request a Consumer Confidence Report, or check current monitoring status, go directly to the federal and state regulators that enforce the Safe Drinking Water Act for Angel Island Subdivision.

Federal Source of Truth

EPA SDWIS, Federal Reports

EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:

View PWS ID MT0000582 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

Montana Drinking Water Authority

Montana's primacy agency administers the Safe Drinking Water Act locally. Search EPA SDWIS for the current state contact, or use the state's public health or environment department portal.

Find MT regulator via EPA SDWIS

Violation Timeline

Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.

Year (latest) Contaminant Category Count EPA Record
2003 Coliform (TCR) MR 3 SDWIS / MT0000582 / 3100
1999 Beryllium, Total MR 4 SDWIS / MT0000582 / 1075
1996 Nitrate MR 2 SDWIS / MT0000582 / 1040
1981 Chromium MR 1 SDWIS / MT0000582 / 1020
1981 Selenium MR 1 SDWIS / MT0000582 / 1045
1981 Fluoride MR 1 SDWIS / MT0000582 / 1025
1981 Mercury MR 1 SDWIS / MT0000582 / 1035
1981 Cadmium MR 1 SDWIS / MT0000582 / 1015
1981 Barium MR 1 SDWIS / MT0000582 / 1010
1981 Arsenic MR 1 SDWIS / MT0000582 / 1005

How Angel Island Subdivision Compares

Cross-reference this system's record against state averages and the federal MCL framework for context.

Metric Angel Island Subdivision Montana avg Federal benchmark
Total violations 17 131.4 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 0 11.5 Indicates a contaminant exceeded a federal MCL
PFAS detection None 62.2% EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 150 492 Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 2,263 regulated public water systems in Montana.

Federal MCL reference, Safe Drinking Water Act thresholds ▼
Contaminant Federal MCL / Action Level Note
Lead 0 mg/L (Action Level: 0.015 mg/L) Lead and Copper Rule treatment technique
Arsenic 0.010 mg/L (10 ppb) Health-based MCL since 2006
Total Coliform Treatment technique (RTCR) Indicator organism, monitoring trigger
PFOA / PFOS (PFAS) 4.0 ppt each (final 2024 rule) Compliance deadline 2029 (EPA proposed extending to 2031, not yet final as of May 2026)
Nitrate (as N) 10 mg/L Acute health risk for infants

Frequently Asked Questions

Is Angel Island Subdivision water safe to drink? ▼
Angel Island Subdivision (PWS ID: MT0000582) has 17 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 150 people using Groundwater sources.
How many people does Angel Island Subdivision serve? ▼
Angel Island Subdivision serves 150 people in Troy, Montana. It is a Private-owned system using Groundwater water sources with 184 service connections.
What type of violations does Angel Island Subdivision have? ▼
Angel Island Subdivision has 17 total violations: 0 health-based violations (MCL exceedances or treatment failures), 16 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Angel Island Subdivision water? ▼
No PFAS testing data is available for Angel Island Subdivision under the EPA's UCMR5 monitoring program.
What water source does Angel Island Subdivision use? ▼
Angel Island Subdivision uses Groundwater as its primary water source. It is classified as a Community Water System (CWS), serving residential populations year-round.
Where does this data come from? ▼
All data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS tracks compliance for all public water systems regulated under the Safe Drinking Water Act.
Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025. This data is provided for informational purposes only.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This system's figures are rendered directly from EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.