County · California
Colusa County, California: drinking water records
This overview covers 6 ZIP codes and 10 community water systems in Colusa County. It also stands in for 0 ZIP codes whose utility has too little EPA data for a page of its own.
System population figures are summed from EPA registry records and can overlap where wholesalers and retail systems serve the same people. They are not a Census county-population estimate.
Water systems with the most complete records
| Water system | People served | PFAS survey results | PFAS found | Health-based violations | Lead, 9 in 10 homes at or below |
|---|---|---|---|---|---|
| City of Colusa CA0610002 | 6,447 | 300 | 0 | 0 | 6.8 ppb |
| City of Williams CA0610004 | 5,538 | 120 | 0 | 0 | 0 ppb |
| Colusa Co. Wwd #1 - Grimes CA0600008 | 512 | 0 | 0 | 33 | 5.8 ppb |
| Mt Terrace MHP OR4105364 | 60 | 0 | 0 | 6 | 0.3 ppb |
| Arbuckle Public Utility District CA0610001 | 2,778 | 0 | 0 | 0 | 0 ppb |
| Maxwell Public Utility District CA0610003 | 1,175 | 0 | 0 | 0 | 1.0 ppb |
| Colusa Co. Wwd #2 - Princeton CA0600013 | 382 | 0 | 0 | 0 | 1.3 ppb |
| Colusa Co. Service Area #2-Stonyford CA0600005 | 250 | 0 | 0 | 0 | 0 ppb |
| Colusa Co. Service Area #1-Century Ranch CA0600012 | 246 | 0 | 0 | 0 | 0 ppb |
| Del Oro Wc - Arbuckle District CA0605011 | 185 | 0 | 0 | 0 | 3.0 ppb |
ZIP reports in Colusa County
No ZIP report in this county is published yet.
Sources and scope
EPA UCMR 5 occurrence data, samples collected 2023-01-03 – 2026-06-17, final release, August 2026 (file dated Aug 28, 2026); EPA SDWIS via ECHO, 2026Q2 extract (file dated Jul 9, 2026); EPA service-area boundaries v3.0; Census 2020 ZCTAs. Page generated 2026-09-03.
Counts cover the systems that report this county to EPA. A water system may cross county lines. "Found" means at least one result at or above the laboratory reporting level; it is not a compliance finding.