Arsenic violations in Montana
33 active public water systems in Montana had a Arsenic violation in the past three years. What Arsenic is and why it matters.
Health effects: Long-term arsenic exposure increases risk of bladder, lung, and skin cancers. It is also associated with cardiovascular disease, type 2 diabetes, and developmental effects in children. Arsenic is classified as a Group A human carcinogen by the EPA.
Systems with a Arsenic violation
Latest quarter first, then largest first| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
Montana State Prison Deer Lodge · Powell County |
2,100 | 8 | 1 | |
|
Crow Agency Water System County |
2,057 | 7 | 2 | |
|
Tiber County Water District Conrad · Pondera County |
750 | 5 | 0 | |
|
Montana State Hospital Complex Warm Springs · Deer Lodge County |
721 | 5 | 1 | |
|
Sheridan Town of Sheridan · Madison County |
632 | 5 | 0 | |
|
Frenchtown High School Frenchtown · Missoula County |
550 | 5 | 0 | |
|
Wibaux Town of Wibaux · Wibaux County |
550 | 8 | 0 | |
|
Box Elder School District 13g Box Elder · Hill County |
500 | 7 | 0 | |
|
Eagleman Community Water County |
400 | 3 | 0 | |
|
Clyde Park Water Dept Clyde Park · Park County |
300 | 6 | 0 | |
|
Wyola Water System County |
281 | 10 | 1 | |
|
Winifred Town of Winifred · Fergus County |
274 | 7 | 1 | |
|
Fort Peck Town of Fort Peck · Valley County |
240 | 3 | 0 | |
|
Anderson School Bozeman · Gallatin County |
220 | 7 | 1 | |
|
Cskt Division of Fire Management County |
190 | 7 | 1 | |
|
Winnett Town of Winnett · Petroleum County |
187 | 8 | 1 | |
|
Bitterroot Gateway MB PK Lolo Lolo · Missoula County |
130 | 6 | 0 | |
|
New Miami Colony Conrad · Pondera County |
130 | 1 | 0 | |
|
Country Haven Estates Whispering Pines Columbus · Stillwater County |
100 | 4 | 0 | |
|
Riders Trailer Court Manhattan · Gallatin County |
100 | 4 | 0 | |
|
Spring Tree Ridge Great Falls · Cascade County |
80 | 4 | 2 | |
|
Swlo and Main Office Missoula · Missoula County |
75 | 7 | 0 | |
|
Hartland Colony Havre · Blaine County |
73 | 5 | 1 | |
|
Barnett Water Users System Helena · Lewis and Clark County |
70 | 6 | 0 | |
|
Milford Colony INC Wolf Creek · Lewis and Clark County |
67 | 7 | 0 | |
|
Thomson Mobile Home Park Belgrade · Gallatin County |
65 | 1 | 0 | |
|
Cardwell School Dist 16 and 31 Cardwell · Jefferson County |
63 | 3 | 1 | |
|
Water Resources Division Missoula · Missoula County |
60 | 8 | 1 | |
|
Beaverhead Jackson Water and Sewer Dist Jackson · Beaverhead County |
58 | 4 | 2 | |
|
Houle Villa Water System County |
50 | 2 | 0 | |
|
Turner Colony Turner · Blaine County |
50 | 7 | 2 | |
|
Hillside Homes Lakeside · Flathead County |
35 | 1 | 0 | |
|
Fishermans Village Subdivision West Yellowstone · Gallatin County |
25 | 9 | 1 |
About this data
A system is counted once if any of its violations in the past three years involved Arsenic, including monitoring and reporting lapses. Rules violated and status in the table are for the whole system, not Arsenic alone.
Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The Montana records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet.