Selenium violations in California
29 active public water systems in California had a Selenium violation in the past three years, 3 of them still unresolved. What Selenium is and why it matters.
Systems with a Selenium violation
Unresolved first, then largest first| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
Halcyon Water System San Luis Obispo County |
110 | 3 | 1 | |
|
Resthaven Mobile Home Park San Luis Obispo County |
99 | 1 | 0 | |
|
Ken Mar Gardens San Luis Obispo County |
84 | 2 | 0 | |
|
Corona, City of Corona · Riverside County |
169,380 | 6 | 0 | |
|
City of Sunnyvale Sunnyvale · Santa Clara County |
157,566 | 5 | 0 | |
|
Norco, City of Norco · Riverside County |
25,068 | 5 | 0 | |
|
Quechan Casino Resort County |
2,950 | 6 | 0 | |
|
Richgrove Community Services District Tulare County |
1,617 | 8 | 3 | |
|
Lakeside Park Association El Dorado County |
924 | 5 | 1 | |
|
Madison Service Dist Yolo County |
876 | 8 | 1 | |
|
Madera MH & RV Park Madera County |
450 | 5 | 0 | |
|
Havasu Water Company County |
361 | 11 | 4 | |
|
Sharondale Mesa HOA Riverside County |
340 | 3 | 0 | |
|
Cacheville Service Dist Yolo County |
239 | 8 | 1 | |
|
Saticoy Country Club-City of Ventura Ventura · Ventura County |
196 | 1 | 0 | |
|
Pauma Valley Water Company San Diego County |
185 | 5 | 2 | |
|
Melody Woods Water Company Santa Clara County |
168 | 3 | 0 | |
|
Foster Road Mutual Water Company Santa Barbara County |
150 | 4 | 0 | |
|
Kinecta Fcu Santa Barbara County |
104 | 4 | 0 | |
|
Round Valley Admin. Complex County |
100 | 6 | 1 | |
|
Pit River Montgomery Creek Rancheria Montgomery Creek Rancheria · County |
90 | 11 | 0 | |
|
John Hovannisian Water System Madera County |
80 | 8 | 1 | |
|
Vista Hills Mutual Water Company Santa Barbara County |
75 | 2 | 0 | |
|
Gold Rock Ranch Imperial County |
45 | 5 | 0 | |
|
Sws Land Development INC Madera County |
35 | 4 | 0 | |
|
Kyburz Mutual Water Company El Dorado County |
30 | 5 | 0 | |
|
Moreton Bay Professional Plaza Santa Barbara County |
25 | 6 | 1 | |
|
Santa Ynez Roblar Mobile Home Park Santa Barbara County |
25 | 4 | 0 | |
|
Silverfork School El Dorado County |
25 | 8 | 0 |
About this data
A system is counted once if any of its violations in the past three years involved Selenium, including monitoring and reporting lapses. Rules violated and status in the table are for the whole system, not Selenium 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.