County · Washington
Columbia County, Washington: drinking water records
This overview covers 2 ZIP codes and 5 community water systems in Columbia 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 |
|---|---|---|---|---|---|
| Dayton Water Department WA5318250 | 3,374 | 0 | 0 | 0 | 0 ppb |
| Starbuck City of WA5383750 | 147 | 0 | 0 | 0 | 0.6 ppb |
| Rivershore Community LLC MT0000414 | 90 | 0 | 0 | 0 | 1 ppb |
| Sunset Mobile Home Park MT0000584 | 45 | 0 | 0 | 0 | 0 ppb |
| Grandview Trailer Court MT0004686 | 165 | 0 | 0 | 0 | not reported |
ZIP reports in Columbia 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.