PlainWater
States → Montana

Community Water System · PWS MT0003374

Hidden Lake Yellowstone County W and S D

Billings, Montana 59105 - drinking water served from groundwater sources to 350 people, tracked in EPA SDWIS and UCMR5.

350
People served
643
EPA violations
12
Health-based
Untested
UCMR5 result

The verdict

EPA records 643 drinking-water violations at Hidden Lake Yellowstone County W and S D, 2% of them health-based - above the Montana per-system average.

643
Total EPA violations on record
2%
Health-based (MCL / treatment failure)
350
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Hidden Lake Yellowstone County W and S D

Hidden Lake Yellowstone County W and S D is a local-owned community water system that delivers drinking water to 350 residents in Billings, Montana (Yellowstone County) through 113 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 643 total violations for this system , of which 12 (2%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 597 monitoring and reporting violations are on file. The most recent violation on record dates to 2023.

The most frequently cited contaminant at this system is Coliform (TCR), recorded in 42 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%).

Hidden Lake Yellowstone County W and S D's 643 violations sit above 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
350
Total Violations
643
Health-Based Violations
12
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Local
Connections
113
County
Yellowstone
School/Daycare
No
MCL Violations
12
Monitoring Violations
597
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Coliform (TCR) MR 42 2007
1,2,4-Trichlorobenzene MR 21 2020
DICHLOROMETHANE MR 21 2020
p-Dichlorobenzene MR 21 2020
Vinyl chloride MR 21 2020
1,2-Dichloroethane MR 21 2020
1,2-Dichloropropane MR 21 2020
Trichloroethylene MR 21 2020
1,1,2-Trichloroethane MR 21 2020
CHLOROBENZENE MR 21 2020
Benzene MR 21 2020
Toluene MR 21 2020
Xylenes, Total MR 21 2020
1,1,1-Trichloroethane MR 21 2020
o-Dichlorobenzene MR 21 2020
Styrene MR 21 2020
trans-1,2-Dichloroethylene MR 21 2020
1,1-Dichloroethylene MR 21 2020
Ethylbenzene MR 21 2020
Carbon tetrachloride MR 21 2020
Tetrachloroethylene MR 21 2020
cis-1,2-Dichloroethylene MR 21 2020
Groundwater Rule MR 16 2023
Lead and Copper Rule MR 13 2014
Coliform (TCR) MCL 12 2015
Nitrate MR 8 1998
Chlorine MR 4 2012
Nitrate-Nitrite MR 3 2004
Consumer Confidence Rule Other 2 2017
Benzo(a)pyrene MR 2 1996

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 Hidden Lake Yellowstone County W and S D.

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 MT0003374 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
2023 Groundwater Rule MR 16 SDWIS / MT0003374 / 0700
2020 1,2,4-Trichlorobenzene MR 21 SDWIS / MT0003374 / 2378
2020 DICHLOROMETHANE MR 21 SDWIS / MT0003374 / 2964
2020 p-Dichlorobenzene MR 21 SDWIS / MT0003374 / 2969
2020 Vinyl chloride MR 21 SDWIS / MT0003374 / 2976
2020 1,2-Dichloroethane MR 21 SDWIS / MT0003374 / 2980
2020 1,2-Dichloropropane MR 21 SDWIS / MT0003374 / 2983
2020 Trichloroethylene MR 21 SDWIS / MT0003374 / 2984
2020 1,1,2-Trichloroethane MR 21 SDWIS / MT0003374 / 2985
2020 CHLOROBENZENE MR 21 SDWIS / MT0003374 / 2989
2020 Benzene MR 21 SDWIS / MT0003374 / 2990
2020 Toluene MR 21 SDWIS / MT0003374 / 2991
2020 Xylenes, Total MR 21 SDWIS / MT0003374 / 2955
2020 1,1,1-Trichloroethane MR 21 SDWIS / MT0003374 / 2981
2020 o-Dichlorobenzene MR 21 SDWIS / MT0003374 / 2968

How Hidden Lake Yellowstone County W and S D Compares

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

Metric Hidden Lake Yellowstone County W and S D Montana avg Federal benchmark
Total violations 643 131.4 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 12 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 350 492 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 Hidden Lake Yellowstone County W and S D water safe to drink? ▼
Hidden Lake Yellowstone County W and S D (PWS ID: MT0003374) has 643 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 350 people using Groundwater sources.
How many people does Hidden Lake Yellowstone County W and S D serve? ▼
Hidden Lake Yellowstone County W and S D serves 350 people in Billings, Montana. It is a Local-owned system using Groundwater water sources with 113 service connections.
What type of violations does Hidden Lake Yellowstone County W and S D have? ▼
Hidden Lake Yellowstone County W and S D has 643 total violations: 12 health-based violations (MCL exceedances or treatment failures), 597 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Hidden Lake Yellowstone County W and S D water? ▼
No PFAS testing data is available for Hidden Lake Yellowstone County W and S D under the EPA's UCMR5 monitoring program.
What water source does Hidden Lake Yellowstone County W and S D use? ▼
Hidden Lake Yellowstone County W and S D 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.