2,4-D violations in California
28 active public water systems in California had a 2,4-D violation in the past three years, 1 of them in the latest quarter of EPA's data. What 2,4-D is and why it matters.
Systems with a 2,4-D violation
Latest quarter first, then largest first| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
South Campo County |
63 | 5 | 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 | |
|
Chemehuevi Water County |
2,200 | 4 | 0 | |
|
Sierra Tahoe Main Lodge El Dorado County |
1,900 | 5 | 0 | |
|
Richgrove Community Services District Tulare County |
1,617 | 8 | 3 | |
|
Madison Service Dist Yolo County |
876 | 8 | 1 | |
|
Madera MH & RV Park Madera County |
450 | 5 | 0 | |
|
Round Valley Piner County |
409 | 5 | 1 | |
|
Havasu Water Company County |
361 | 11 | 4 | |
|
Cacheville Service Dist Yolo County |
239 | 8 | 1 | |
|
Foster Road Mutual Water Company Santa Barbara County |
150 | 4 | 0 | |
|
Round Valley Hidden Oaks Casino and Restaurant County |
137 | 6 | 2 | |
|
Gold Beach Park El Dorado County |
134 | 2 | 0 | |
|
Acton Conservation Camp #11 Los Angeles County |
90 | 4 | 0 | |
|
Pit River Montgomery Creek Rancheria Montgomery Creek Rancheria · County |
90 | 11 | 0 | |
|
San Joaquin Wine Company Madera County |
90 | 2 | 0 | |
|
Resource Center Santa Barbara · Santa Barbara County |
85 | 2 | 0 | |
|
Round Valley Agency County |
84 | 7 | 1 | |
|
John Hovannisian Water System Madera County |
80 | 8 | 1 | |
|
Sans End RV Park County |
77 | 5 | 0 | |
|
Rancho Villanueva LLC County |
68 | 5 | 1 | |
|
Brookside MHP San Bernardino County |
65 | 7 | 3 | |
|
Madera Irrigation District Madera County |
50 | 4 | 2 | |
|
Kyburz Mutual Water Company El Dorado County |
30 | 5 | 0 | |
|
Moreton Bay Professional Plaza Santa Barbara County |
25 | 6 | 1 | |
|
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 2,4-D, including monitoring and reporting lapses. Rules violated and status in the table are for the whole system, not 2,4-D 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.