PlainWater
States → Montana

Non-Transient Non-Community Water System · PWS MT0001820

Lone Mountain Guest Ranch

Big Sky, Montana 59716 - drinking water served from groundwater sources to 75 people, tracked in EPA SDWIS and UCMR5.

75
People served
1,115
EPA violations
5
Health-based
Untested
UCMR5 result

The verdict

EPA records 1,115 drinking-water violations at Lone Mountain Guest Ranch - above the Montana per-system average.

1,115
Total EPA violations on record
0%
Health-based (MCL / treatment failure)
75
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Lone Mountain Guest Ranch

Lone Mountain Guest Ranch is a private-owned non-transient non-community water system that delivers drinking water to 75 residents in Big Sky, Montana (Gallatin County) through 25 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 1,115 total violations for this system , of which 5 (0%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 1,108 monitoring and reporting violations are on file. The most recent violation on record dates to 2024.

The most frequently cited contaminant at this system is Coliform (TCR), recorded in 28 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, 5 of 45 UCMR5-tested systems have reported PFAS detections (11.1%).

Lone Mountain Guest Ranch's 1,115 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
75
Total Violations
1,115
Health-Based Violations
5
Water Source
Groundwater

System Details

System Type
Non-Transient Non-Community
Owner Type
Private
Connections
25
County
Gallatin
School/Daycare
No
MCL Violations
5
Monitoring Violations
1,108
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Coliform (TCR) MR 28 2007
cis-1,2-Dichloroethylene MR 26 2020
DICHLOROMETHANE MR 26 2020
o-Dichlorobenzene MR 26 2020
Vinyl chloride MR 26 2020
Carbon tetrachloride MR 26 2020
1,2-Dichloropropane MR 26 2020
1,1,2-Trichloroethane MR 26 2020
Tetrachloroethylene MR 26 2020
Benzene MR 26 2020
Ethylbenzene MR 26 2020
1,2,4-Trichlorobenzene MR 26 2020
Xylenes, Total MR 26 2020
p-Dichlorobenzene MR 26 2020
1,1-Dichloroethylene MR 26 2020
1,1,1-Trichloroethane MR 26 2020
Trichloroethylene MR 26 2020
CHLOROBENZENE MR 26 2020
Toluene MR 26 2020
1,2-Dichloroethane MR 26 2020
Styrene MR 26 2020
trans-1,2-Dichloroethylene MR 26 2020
Endrin MR 21 2020
BHC-GAMMA MR 21 2020
Methoxychlor MR 21 2020
Toxaphene MR 21 2020
Dalapon MR 21 2020
Di(2-ethylhexyl) adipate MR 21 2020
Picloram MR 21 2020
Dinoseb MR 21 2020

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 Lone Mountain Guest Ranch.

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 MT0001820 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
2024 Lead and Copper Rule MR 10 SDWIS / MT0001820 / 5000
2022 Groundwater Rule MR 8 SDWIS / MT0001820 / 0700
2020 cis-1,2-Dichloroethylene MR 26 SDWIS / MT0001820 / 2380
2020 DICHLOROMETHANE MR 26 SDWIS / MT0001820 / 2964
2020 o-Dichlorobenzene MR 26 SDWIS / MT0001820 / 2968
2020 Vinyl chloride MR 26 SDWIS / MT0001820 / 2976
2020 Carbon tetrachloride MR 26 SDWIS / MT0001820 / 2982
2020 1,2-Dichloropropane MR 26 SDWIS / MT0001820 / 2983
2020 1,1,2-Trichloroethane MR 26 SDWIS / MT0001820 / 2985
2020 Tetrachloroethylene MR 26 SDWIS / MT0001820 / 2987
2020 Benzene MR 26 SDWIS / MT0001820 / 2990
2020 Ethylbenzene MR 26 SDWIS / MT0001820 / 2992
2020 1,2,4-Trichlorobenzene MR 26 SDWIS / MT0001820 / 2378
2020 Xylenes, Total MR 26 SDWIS / MT0001820 / 2955
2020 p-Dichlorobenzene MR 26 SDWIS / MT0001820 / 2969

How Lone Mountain Guest Ranch Compares

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

Metric Lone Mountain Guest Ranch Montana avg Federal benchmark
Total violations 1,115 131.4 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 5 11.5 Indicates a contaminant exceeded a federal MCL
PFAS detection None 11.1% EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 75 492 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 Lone Mountain Guest Ranch water safe to drink? ▼
Lone Mountain Guest Ranch (PWS ID: MT0001820) has 1115 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 75 people using Groundwater sources.
How many people does Lone Mountain Guest Ranch serve? ▼
Lone Mountain Guest Ranch serves 75 people in Big Sky, Montana. It is a Private-owned system using Groundwater water sources with 25 service connections.
What type of violations does Lone Mountain Guest Ranch have? ▼
Lone Mountain Guest Ranch has 1,115 total violations: 5 health-based violations (MCL exceedances or treatment failures), 1,108 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Lone Mountain Guest Ranch water? ▼
No PFAS testing data is available for Lone Mountain Guest Ranch under the EPA's UCMR5 monitoring program.
What water source does Lone Mountain Guest Ranch use? ▼
Lone Mountain Guest Ranch uses Groundwater as its primary water source. It is classified as a Non-Transient Non-Community Water System, serving the same people for at least 6 months per year.
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.