Tapcensus

Cyanide violations in California

6 active public water systems in California 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
SystemServesStatusRules violated, 3 yrUnresolved
Quechan Casino Resort
County 		2,950 6 0
Tuolumne Black Oak Casino
County 		2,600 2 0
Coyote Valley System
County 		850 5 0
Havasu Water Company
County 		361 11 4
Pit River Montgomery Creek Rancheria
Montgomery Creek Rancheria · County 		90 11 0
Old Sugar Mill Winery
Yolo County 		25 2 1
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 California 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. Retrieved from ECHO on Oct 11, 2026.