Is Lewistown, MT Tap Water Safe? Quality & Contaminants

What was found in Lewistown'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	190 µg/L 1.9% of the EPA limit 10000 µg/L Main supplier: LEWISTOWN CITY OF · 5,923 people · 2019 Highest in the city: 17035 µg/L — KING RANCH COLONY · 56 people · 2019	4/5	SYR4
Fluoride	595 µg/L 15% of the EPA limit 4000 µg/L Main supplier: LEWISTOWN CITY OF · 5,923 people · 2017 Highest in the city: 1490 µg/L — SPRING CREEK COLONY LEWISTOWN · 48 people · 2017	4/5	SYR4
Copper	91.6 µg/L 7% of the EPA limit 1300 µg/L Main supplier: LEWISTOWN CITY OF · 5,923 people · 2019 Highest in the city: 121.8 µg/L — KING RANCH COLONY · 56 people · 2016	5/5	SYR4
Barium	80 µg/L 4% of the EPA limit 2000 µg/L Highest in the city: KING RANCH COLONY · 56 people · 2012	1/5	SYR4
Lead	1.9 µg/L 13% of the EPA limit 15 µg/L Main supplier: LEWISTOWN CITY OF · 5,923 people · 2019 Highest in the city: 10.8 µg/L — MOUNTAIN ACRES MB HM PK · 320 people · 2019	3/5	SYR4
Gross Alpha, Excl. Radon And U	6.2 pCi/L 41% of the EPA limit 15 pCi/L Highest in the city: DEERFIELD HUTTERITE COLONY · 51 people · 2013	2/5	SYR4
Combined Radium (-226 And -228)	2 pCi/L 40% of the EPA limit 5 pCi/L Highest in the city: DEERFIELD HUTTERITE COLONY · 51 people · 2013	1/5	SYR4
Combined Uranium	1 µg/L 3.3% of the EPA limit 30 µg/L Highest in the city: KING RANCH COLONY · 56 people · 2012	1/5	SYR4
Selenium	1 µg/L 2% of the EPA limit 50 µg/L Highest in the city: KING RANCH COLONY · 56 people · 2012	1/5	SYR4
Lead	0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: LEWISTOWN CITY OF · 5,923 people · 2025	5/5	LCR

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 Lewistown

Supplier	Population served
LEWISTOWN CITY OF	5,923
MOUNTAIN ACRES MB HM PK	320
KING RANCH COLONY	56
DEERFIELD HUTTERITE COLONY	51
SPRING CREEK COLONY LEWISTOWN	48

Frequently asked questions about Lewistown tap water

Is Lewistown tap water safe to drink?

EPA testing detected 10 contaminants in the water serving Lewistown. 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 Lewistown?

5 public water suppliers report drinking-water monitoring for Lewistown, Montana to the EPA. Each is listed above with its population served.

What contaminants are in Lewistown's water?

The contaminants EPA monitoring detected in Lewistown include Nitrate-Nitrite, Fluoride, Copper, Barium, Lead. 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.