Groundwater Rule (GWR) violations in California
31 active public water systems in California had a Groundwater Rule (GWR) violation in the past three years, 33 of them in the latest quarter of EPA's data. What Groundwater Rule (GWR) is and why it matters.
Systems with a Groundwater Rule (GWR) violation
Latest quarter first, then largest first| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
Pala North County |
14,280 | 3 | 1 | |
|
California Institution for Men San Bernardino County |
10,667 | 1 | 1 | |
|
Big River Development Big River · County |
3,550 | 9 | 4 | |
|
Santa Clara Valley Medical Center Santa Clara County |
3,000 | 3 | 2 | |
|
Tule River Reservation Main Tule River Reservation · County |
2,560 | 9 | 2 | |
|
Little Bear Water Company Monterey County |
2,327 | 1 | 1 | |
|
Csp-Andrew Molera State Reserve Monterey County |
1,005 | 2 | 2 | |
|
Middletown Rancheria Community Water System County |
487 | 4 | 3 | |
|
Round Valley Piner County |
409 | 5 | 1 | |
|
Big Sandy Rancheria Big Sandy Rancheria · County |
408 | 5 | 2 | |
|
Pala South County |
360 | 1 | 1 | |
|
Aha Quin County |
315 | 3 | 2 | |
|
DD Mobile Home Park County |
275 | 9 | 3 | |
|
DI Giorgio School Water System Kern County |
268 | 3 | 0 | |
|
Washoe Tribe Woodfords Woodfords · County |
250 | 2 | 1 | |
|
Del Oro California Pines District Tulare County |
249 | 1 | 1 | |
|
Table Bluff (new) Reservation County |
230 | 4 | 1 | |
|
Utu Utu Gwaitu Paiute Tribe Benton Paiute Reservation · County |
222 | 4 | 3 | |
|
Yurok Requa County |
215 | 7 | 2 | |
|
James Court Water System Sonoma County |
208 | 1 | 1 | |
|
Redwood Valley Rancheria County |
152 | 4 | 1 | |
|
Round Valley Hidden Oaks Casino and Restaurant County |
137 | 6 | 2 | |
|
Round Valley Health Clinic County |
119 | 7 | 3 | |
|
Round Valley Agency County |
84 | 7 | 1 | |
|
Yurok Kepel County |
76 | 7 | 1 | |
|
Toledo MHP County |
68 | 5 | 3 | |
|
Big Bend Big Bend Rv Park · County |
50 | 4 | 2 | |
|
Avi Kwa Ame Farms North County |
40 | 4 | 3 | |
|
North Coast Wine Co. Sonoma County |
39 | 1 | 1 | |
|
Inyo County Pwd Lone Pine Inyo County |
1,835 | 4 | 1 | |
|
Six Acres Water Company Sonoma County |
66 | 2 | 1 |
About this data
A system is counted once if any of its violations in the past three years involved Groundwater Rule (GWR), including monitoring and reporting lapses. Rules violated and status in the table are for the whole system, not Groundwater Rule (GWR) 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.