California County Water Quality Reports

Alameda County, CA: Lead Above EPA Limits — 69/100 (2026)

2026 report: Alameda County, CA scores 69/100 (Grade C). 75 ZIP codes analyzed. 100 EPA violations found. Lead above EPA limits. Free report with contam...

Alpine County, CA: 1 Violation — 62/100 (2026)

2026 report: Alpine County, CA scores 62/100 (Grade C). 5 ZIP codes analyzed. 1 EPA violation found. Free report with contaminant data and filter picks.

Amador County, CA: Lead Above EPA Limits — 62/100 (2026)

2026 report: Amador County, CA scores 62/100 (Grade C). 18 ZIP codes analyzed. 19 EPA violations found. Lead above EPA limits. Free report with contamin...

Butte County, CA: 30 Health Violations — 78/100 (2026)

2026 report: Butte County, CA scores 78/100 (Grade B). 29 ZIP codes analyzed. 62 EPA violations found. Free report with contaminant data and filter picks.

Calaveras County, CA: 9 Health Violations — 63/100 (2026)

2026 report: Calaveras County, CA scores 63/100 (Grade C). 16 ZIP codes analyzed. 11 EPA violations found. Free report with contaminant data and filter ...

Colusa County, CA: 1 Health Violation — 80/100 (2026)

2026 report: Colusa County, CA scores 80/100 (Grade B). 5 ZIP codes analyzed. 9 EPA violations found. Free report with contaminant data and filter picks.

Contra Costa County, CA: 88 Health Violations — 68/100

2026 report: Contra Costa County, CA scores 68/100 (Grade C). 35 ZIP codes analyzed. 143 EPA violations found. Free report with contaminant data and fil...

Del Norte County, CA: 3 Health Violations — 84/100 (2026)

2026 report: Del Norte County, CA scores 84/100 (Grade B). 9 ZIP codes analyzed. 10 EPA violations found. Free report with contaminant data and filter p...

El Dorado County, CA: Lead Above EPA Limits — 70/100 (2026)

2026 report: El Dorado County, CA scores 70/100 (Grade B). 24 ZIP codes analyzed. 53 EPA violations found. Lead above EPA limits. Free report with conta...

Fresno County, CA: 150 Health Violations — 70/100 (2026)

2026 report: Fresno County, CA scores 70/100 (Grade B). 102 ZIP codes analyzed. 380 EPA violations found. Free report with contaminant data and filter p...

Glenn County, CA: 2 Violations — 81/100 (2026)

2026 report: Glenn County, CA scores 81/100 (Grade B). 12 ZIP codes analyzed. 2 EPA violations found. Free report with contaminant data and filter picks.

Humboldt County, CA: Lead Above EPA Limits — 82/100 (2026)

2026 report: Humboldt County, CA scores 82/100 (Grade B). 41 ZIP codes analyzed. 84 EPA violations found. Lead above EPA limits. Free report with contam...

Imperial County, CA: 30 Health Violations — 80/100 (2026)

2026 report: Imperial County, CA scores 80/100 (Grade B). 22 ZIP codes analyzed. 75 EPA violations found. Free report with contaminant data and filter p...

Inyo County, CA: 8 Health Violations — 59/100 (2026)

2026 report: Inyo County, CA scores 59/100 (Grade C). 42 ZIP codes analyzed. 36 EPA violations found. Free report with contaminant data and filter picks.

Kern County, CA: Lead Above EPA Limits — 65/100 (2026)

2026 report: Kern County, CA scores 65/100 (Grade C). 102 ZIP codes analyzed. 356 EPA violations found. Lead above EPA limits. Free report with contamin...

Kings County, CA: 45 Health Violations — 75/100 (2026)

2026 report: Kings County, CA scores 75/100 (Grade B). 9 ZIP codes analyzed. 61 EPA violations found. Free report with contaminant data and filter picks.

Lake County, CA: 15 Health Violations — 75/100 (2026)

2026 report: Lake County, CA scores 75/100 (Grade B). 21 ZIP codes analyzed. 25 EPA violations found. Free report with contaminant data and filter picks.

Lassen County, CA Water Safety: 75/100 (2026)

2026 report: Lassen County, CA scores 75/100 (Grade B). 18 ZIP codes analyzed. No EPA violations. Free report with contaminant data and filter picks.

Los Angeles County, CA: 454 Health Violations — 72/100

2026 report: Los Angeles County, CA scores 72/100 (Grade B). 459 ZIP codes analyzed. 1342 EPA violations found. Free report with contaminant data and fi...

Madera County, CA: 46 Health Violations — 60/100 (2026)

2026 report: Madera County, CA scores 60/100 (Grade C). 16 ZIP codes analyzed. 63 EPA violations found. Free report with contaminant data and filter picks.

Marin County, CA: 24 Health Violations — 74/100 (2026)

2026 report: Marin County, CA scores 74/100 (Grade B). 33 ZIP codes analyzed. 37 EPA violations found. Free report with contaminant data and filter picks.

Mariposa County, CA: 1 Violation — 58/100 (2026)

2026 report: Mariposa County, CA scores 58/100 (Grade C). 6 ZIP codes analyzed. 1 EPA violation found. Free report with contaminant data and filter picks.

Mendocino County, CA: Lead Above EPA Limits — 74/100 (2026)

2026 report: Mendocino County, CA scores 74/100 (Grade B). 29 ZIP codes analyzed. 32 EPA violations found. Lead above EPA limits. Free report with conta...

Merced County, CA: 39 Health Violations — 77/100 (2026)

2026 report: Merced County, CA scores 77/100 (Grade B). 22 ZIP codes analyzed. 70 EPA violations found. Free report with contaminant data and filter picks.

Modoc County, CA: 4 Health Violations — 78/100 (2026)

2026 report: Modoc County, CA scores 78/100 (Grade B). 9 ZIP codes analyzed. 11 EPA violations found. Free report with contaminant data and filter picks.

Mono County, CA: 9 Health Violations — 68/100 (2026)

2026 report: Mono County, CA scores 68/100 (Grade C). 6 ZIP codes analyzed. 20 EPA violations found. Free report with contaminant data and filter picks.

Monterey County, CA: 55 Health Violations — 71/100 (2026)

2026 report: Monterey County, CA scores 71/100 (Grade B). 36 ZIP codes analyzed. 146 EPA violations found. Free report with contaminant data and filter ...

Napa County, CA: Lead Above EPA Limits — 71/100 (2026)

2026 report: Napa County, CA scores 71/100 (Grade B). 13 ZIP codes analyzed. 19 EPA violations found. Lead above EPA limits. Free report with contaminan...

Nevada County, CA: Lead Above EPA Limits — 68/100 (2026)

2026 report: Nevada County, CA scores 68/100 (Grade C). 14 ZIP codes analyzed. 9 EPA violations found. Lead above EPA limits. Free report with contamina...

Orange County, CA: 74 Health Violations — 87/100 (2026)

2026 report: Orange County, CA scores 87/100 (Grade A). 143 ZIP codes analyzed. 299 EPA violations found. Free report with contaminant data and filter p...

Placer County, CA: Lead Above EPA Limits — 69/100 (2026)

2026 report: Placer County, CA scores 69/100 (Grade C). 31 ZIP codes analyzed. 30 EPA violations found. Lead above EPA limits. Free report with contamin...

Plumas County, CA: 11 Health Violations — 66/100 (2026)

2026 report: Plumas County, CA scores 66/100 (Grade C). 14 ZIP codes analyzed. 21 EPA violations found. Free report with contaminant data and filter picks.

Riverside County, CA: Lead Above EPA Limits — 73/100 (2026)

2026 report: Riverside County, CA scores 73/100 (Grade B). 101 ZIP codes analyzed. 174 EPA violations found. Lead above EPA limits. Free report with con...

Sacramento County, CA: Lead Above EPA Limits — 80/100 (2026)

2026 report: Sacramento County, CA scores 80/100 (Grade B). 133 ZIP codes analyzed. 225 EPA violations found. Lead above EPA limits. Free report with co...

San Benito County, CA: 12 Health Violations — 67/100 (2026)

2026 report: San Benito County, CA scores 67/100 (Grade C). 5 ZIP codes analyzed. 27 EPA violations found. Free report with contaminant data and filter ...

San Bernardino County, CA: Lead Above EPA Limits — 70/100

2026 report: San Bernardino County, CA scores 70/100 (Grade B). 114 ZIP codes analyzed. 245 EPA violations found. Lead above EPA limits. Free report wit...

San Diego County, CA: Lead Above EPA Limits — 72/100 (2026)

2026 report: San Diego County, CA scores 72/100 (Grade B). 187 ZIP codes analyzed. 1331 EPA violations found. Lead above EPA limits. Free report with co...

San Francisco County, CA: 354 Health Violations — 55/100

2026 report: San Francisco County, CA scores 55/100 (Grade C). 59 ZIP codes analyzed. 413 EPA violations found. Free report with contaminant data and fi...

San Joaquin County, CA: 142 Health Violations — 78/100

2026 report: San Joaquin County, CA scores 78/100 (Grade B). 55 ZIP codes analyzed. 215 EPA violations found. Free report with contaminant data and filt...

San Luis Obispo County, CA: Lead Above EPA Limits — 71/100

2026 report: San Luis Obispo County, CA scores 71/100 (Grade B). 34 ZIP codes analyzed. 102 EPA violations found. Lead above EPA limits. Free report wit...

San Mateo County, CA: 32 Health Violations — 72/100 (2026)

2026 report: San Mateo County, CA scores 72/100 (Grade B). 35 ZIP codes analyzed. 48 EPA violations found. Free report with contaminant data and filter ...

Santa Barbara County, CA: 8 Health Violations — 63/100

2026 report: Santa Barbara County, CA scores 63/100 (Grade C). 41 ZIP codes analyzed. 64 EPA violations found. Free report with contaminant data and fil...

Santa Clara County, CA: Lead Above EPA Limits — 78/100

2026 report: Santa Clara County, CA scores 78/100 (Grade B). 104 ZIP codes analyzed. 78 EPA violations found. Lead above EPA limits. Free report with co...

Santa Cruz County, CA: 61 Health Violations — 64/100 (2026)

2026 report: Santa Cruz County, CA scores 64/100 (Grade C). 22 ZIP codes analyzed. 87 EPA violations found. Free report with contaminant data and filter...

Shasta County, CA: 7 Health Violations — 82/100 (2026)

2026 report: Shasta County, CA scores 82/100 (Grade B). 31 ZIP codes analyzed. 23 EPA violations found. Free report with contaminant data and filter picks.

Sierra County, CA: 2 Health Violations — 75/100 (2026)

2026 report: Sierra County, CA scores 75/100 (Grade B). 7 ZIP codes analyzed. 6 EPA violations found. Free report with contaminant data and filter picks.

Siskiyou County, CA: Lead Above EPA Limits — 83/100 (2026)

2026 report: Siskiyou County, CA scores 83/100 (Grade B). 19 ZIP codes analyzed. 33 EPA violations found. Lead above EPA limits. Free report with contam...

Solano County, CA: 35 Health Violations — 79/100 (2026)

2026 report: Solano County, CA scores 79/100 (Grade B). 18 ZIP codes analyzed. 43 EPA violations found. Free report with contaminant data and filter picks.

Sonoma County, CA: Lead Above EPA Limits — 80/100 (2026)

2026 report: Sonoma County, CA scores 80/100 (Grade B). 63 ZIP codes analyzed. 88 EPA violations found. Lead above EPA limits. Free report with contamin...

Stanislaus County, CA: Lead Above EPA Limits — 84/100 (2026)

2026 report: Stanislaus County, CA scores 84/100 (Grade B). 26 ZIP codes analyzed. 74 EPA violations found. Lead above EPA limits. Free report with cont...

Sutter County, CA: 3 Violations — 85/100 (2026)

2026 report: Sutter County, CA scores 85/100 (Grade A). 7 ZIP codes analyzed. 3 EPA violations found. Free report with contaminant data and filter picks.

Tehama County, CA: 19 Health Violations — 81/100 (2026)

2026 report: Tehama County, CA scores 81/100 (Grade B). 14 ZIP codes analyzed. 31 EPA violations found. Free report with contaminant data and filter picks.

Trinity County, CA: Lead Above EPA Limits — 81/100 (2026)

2026 report: Trinity County, CA scores 81/100 (Grade B). 10 ZIP codes analyzed. 20 EPA violations found. Lead above EPA limits. Free report with contami...

Tulare County, CA: Lead Above EPA Limits — 63/100 (2026)

2026 report: Tulare County, CA scores 63/100 (Grade C). 36 ZIP codes analyzed. 191 EPA violations found. Lead above EPA limits. Free report with contami...

Tuolumne County, CA: 12 Health Violations — 64/100 (2026)

2026 report: Tuolumne County, CA scores 64/100 (Grade C). 16 ZIP codes analyzed. 36 EPA violations found. Free report with contaminant data and filter p...

Ventura County, CA: 50 Health Violations — 58/100 (2026)

2026 report: Ventura County, CA scores 58/100 (Grade C). 45 ZIP codes analyzed. 164 EPA violations found. Free report with contaminant data and filter p...

Yolo County, CA: 9 Health Violations — 84/100 (2026)

2026 report: Yolo County, CA scores 84/100 (Grade B). 19 ZIP codes analyzed. 32 EPA violations found. Free report with contaminant data and filter picks.

Yuba County, CA: Lead Above EPA Limits — 67/100 (2026)

2026 report: Yuba County, CA scores 67/100 (Grade C). 13 ZIP codes analyzed. 12 EPA violations found. Lead above EPA limits. Free report with contaminan...