Cyanide violations in Montana
9 active public water systems in Montana had a Cyanide violation in the past three years. What Cyanide is and why it matters.
Health effects: Acute high-dose cyanide exposure interferes with cellular oxygen use and can cause rapid deterioration of the central nervous system, including headache, dizziness, and in severe cases, loss of consciousness. Chronic exposure at lower levels is associated with thyroid dysfunction and nerve damage. Most drinking water violations pose chronic rather than acute risk.
Systems with a Cyanide violation
Latest quarter first, then largest first| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
Crow Agency Water System County |
2,057 | 7 | 2 | |
|
Wyola Water System County |
281 | 10 | 1 | |
|
Curious Minds Montessori Preschool Stevensville · Ravalli County |
205 | 4 | 1 | |
|
Cskt Division of Fire Management County |
190 | 7 | 1 | |
|
Bucks T4 Big Sky · Gallatin County |
153 | 2 | 0 | |
|
Cmrwa Musselshell Judith Rural Water Sys Harlowton · Wheatland County |
100 | 2 | 0 | |
|
All West Business Park Lot 3 Bozeman · Gallatin County |
70 | 4 | 0 | |
|
Houle Villa Water System County |
50 | 2 | 0 | |
|
Silver Run School Carbon County |
50 | 3 | 0 |
About this data
A system is counted once if any of its violations in the past three years involved Cyanide, including monitoring and reporting lapses. Rules violated and status in the table are for the whole system, not Cyanide 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.