What was found in Big Sky's water
The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Nitrate-Nitrite | 3045 µg/L 30% of the EPA limit 10000 µg/L Main supplier: BIG SKY COUNTY WATER AND SEWER DIST 363 · 4,132 people · 2019 | 8/10 | SYR4 |
| Fluoride | 680 µg/L 17% of the EPA limit 4000 µg/L Main supplier: BIG SKY COUNTY WATER AND SEWER DIST 363 · 4,132 people · 2019
Highest in the city: 1680 µg/L — RAMSHORN VIEW ESTATES · 185 people · 2019 | 9/10 | SYR4 |
| Copper | 186.75 µg/L 14% of the EPA limit 1300 µg/L Main supplier: BIG SKY COUNTY WATER AND SEWER DIST 363 · 4,132 people · 2019
Highest in the city: 1020 µg/L — FIRELIGHT MEADOWS LLC · 350 people · 2017 | 10/10 | SYR4 |
| Barium | 205 µg/L 10% of the EPA limit 2000 µg/L Main supplier: BIG SKY COUNTY WATER AND SEWER DIST 363 · 4,132 people · 2019 | 6/10 | SYR4 |
| Arsenic | 18.45 µg/L 185% of the EPA limit, at the 95th percentile of samples — 10 µg/L Main supplier: BIG SKY COUNTY WATER AND SEWER DIST 363 · 4,132 people · 2019 | 6/10 | SYR4 |
| Lead | 10.95 µg/L 73% of the EPA limit 15 µg/L Main supplier: BIG SKY COUNTY WATER AND SEWER DIST 363 · 4,132 people · 2019
Highest in the city: 17.6 µg/L — LOWER PIONEER MOUNTAIN WATER SYSTEM · 350 people · 2017 | 8/10 | SYR4 |
| Gross Alpha, Excl. Radon And U | 6.1 pCi/L 41% of the EPA limit 15 pCi/L Main supplier: BIG SKY COUNTY WATER AND SEWER DIST 363 · 4,132 people · 2013
Highest in the city: 9.9 pCi/L — ANTLER RIDGE HOMEOWNERS ASSOCIATION · 50 people · 2019 | 8/10 | SYR4 |
| Total Haloacetic Acids (HAA5) | 8.9 µg/L 15% of the EPA limit 60 µg/L Highest in the city: MT MOONLIGHT BASIN · 355 people · 2017 | 2/10 | SYR4 |
| TTHM | 7.66 µg/L 9.6% of the EPA limit 80 µg/L Highest in the city: FIRELIGHT MEADOWS LLC · 350 people · 2018 | 3/10 | SYR4 |
| Dichloroacetic Acid | 6.3 µg/L No EPA limit set Highest in the city: MT MOONLIGHT BASIN · 355 people · 2017 | 2/10 | SYR4 |
| Combined Radium (-226 And -228) | 5.02 pCi/L 100% of the EPA limit, at the 95th percentile of samples — 5 pCi/L Highest in the city: LONE VIEW RIDGE WATER SYSTEM · 37 people · 2019 | 5/10 | SYR4 |
| Combined Uranium | 1 µg/L 3.3% of the EPA limit 30 µg/L Main supplier: BIG SKY COUNTY WATER AND SEWER DIST 363 · 4,132 people · 2013
Highest in the city: 5 µg/L — ANTLER RIDGE HOMEOWNERS ASSOCIATION · 50 people · 2019 | 4/10 | SYR4 |
| Chloroform | 4.5 µg/L No EPA limit set Highest in the city: MT MOONLIGHT BASIN · 355 people · 2018 | 3/10 | SYR4 |
| Selenium | 2 µg/L 4% of the EPA limit 50 µg/L Main supplier: BIG SKY COUNTY WATER AND SEWER DIST 363 · 4,132 people · 2019
Highest in the city: 3 µg/L — RAMSHORN VIEW ESTATES · 185 people · 2019 | 4/10 | SYR4 |
| Antimony, Total | 2.95 µg/L 49% of the EPA limit 6 µg/L Main supplier: BIG SKY COUNTY WATER AND SEWER DIST 363 · 4,132 people · 2019 | 1/10 | SYR4 |
| Bromodichloromethane | 2.76 µg/L No EPA limit set Highest in the city: FIRELIGHT MEADOWS LLC · 350 people · 2018 | 1/10 | SYR4 |
| Chromium | 2.6 µg/L 2.6% of the EPA limit 100 µg/L Highest in the city: SPANISH PEAKS MOUNTAIN CLUB · 40 people · 2019 | 1/10 | SYR4 |
| Dibromochloromethane | 1.7 µg/L No EPA limit set Highest in the city: FIRELIGHT MEADOWS LLC · 350 people · 2018 | 1/10 | SYR4 |
| Dibromoacetic Acid | 1.5 µg/L No EPA limit set Highest in the city: MT MOONLIGHT BASIN · 355 people · 2017 | 2/10 | SYR4 |
| Gross Beta Particle Activity | 1.1 pCi/L No EPA limit set Highest in the city: ANTLER RIDGE HOMEOWNERS ASSOCIATION · 50 people · 2014 | 1/10 | SYR4 |
| Xylenes, Total | 1.1 µg/L 0% of the EPA limit 10000 µg/L Main supplier: BIG SKY COUNTY WATER AND SEWER DIST 363 · 4,132 people · 2019 | 1/10 | SYR4 |
| Trichloroacetic Acid | 1 µg/L No EPA limit set Highest in the city: MT MOONLIGHT BASIN · 355 people · 2017 | 2/10 | SYR4 |
| Lead | 0.0048 mg/L 32% of the EPA limit 0.0150 mg/L Main supplier: BIG SKY COUNTY WATER AND SEWER DIST 363 · 4,132 people · 2025
Highest in the city: 0.0120 mg/L — ENCAMPMENT TRAIL · 100 people · 2026 | 10/10 | LCR |
| PFBS | 0.0031 µg/L No EPA limit set Main supplier: BIG SKY COUNTY WATER AND SEWER DIST 363 · 4,132 people · 2025 | 1/10 | UCMR-5 |
Each bar shows the measured level as a share of the EPA limit: green is
well under, amber is close to it, red is over. For lead and copper the
limit applies to exactly the 90th-percentile figure shown, so red there
means a real exceedance. For everything else the limit applies to a
running annual average while the figure is the 95th percentile of the
system's samples — over 100% is worth reading, but is not by itself a
violation.
Formal violations are listed separately.
These are the utilities' own EPA-reported results, not a city-wide
average. A detection means the lab measured the
substance — it isn't the same as exceeding a legal limit. Hover a source
tag to see the EPA program and years behind each figure.
Water suppliers serving Big Sky
| Supplier | Population served |
|---|---|
| BIG SKY COUNTY WATER AND SEWER DIST 363 | 4,132 |
| ANDESITE RIDGE WATER SYSTEM | 450 |
| MT MOONLIGHT BASIN | 355 |
| LOWER PIONEER MOUNTAIN WATER SYSTEM | 350 |
| FIRELIGHT MEADOWS LLC | 350 |
| RAMSHORN VIEW ESTATES | 185 |
| ENCAMPMENT TRAIL | 100 |
| ANTLER RIDGE HOMEOWNERS ASSOCIATION | 50 |
| SPANISH PEAKS MOUNTAIN CLUB | 40 |
| LONE VIEW RIDGE WATER SYSTEM | 37 |
Frequently asked questions about Big Sky tap water
Is Big Sky tap water safe to drink?
EPA testing detected 24 contaminants in the water serving Big Sky. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.
How many water suppliers serve Big Sky?
10 public water suppliers report drinking-water monitoring for Big Sky, Montana to the EPA. Each is listed above with its population served.
What contaminants are in Big Sky's water?
The contaminants EPA monitoring detected in Big Sky include Nitrate-Nitrite, Fluoride, Copper, Barium, Arsenic. The full list, with the level at the main supplier and the data source, is in the table above.
Where does this data come from?
Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.