Polk County Water Report

Polk County's water systems carry a failing grade, scoring 14.8 out of 100. Over the past five years, EPA SDWIS records 27 health-based violations — a pattern that public water utilities are required to disclose and correct.

Under the Clean Water Act §303(d), EPA ATTAINS tracks whether waterways meet quality standards for drinking, recreation, and aquatic life (reporting cycle: 2022). A notable 14.5% of assessed waterways carry an impairment designation (32 of 220 water bodies) across Polk County's watersheds. The leading impairment causes are ph and dissolved oxygen - critical. Impairment does not mean tap water is unsafe — it measures ambient waterway conditions upstream of treatment, not finished drinking water.

USGS NWIS gauge data (as of 2026-05-14T14:00:00.000-05:00) puts Cossatot River at 20.3 cfs — well below its long-term average at 11% of mean — low-flow conditions worth noting for water-dependent ecosystems. Streamflow is a leading indicator of drought stress, sediment load, and dilution capacity: low flows concentrate pollutants and warm water temperatures, stressing aquatic life and, in surface-water-dependent systems, the source water quality for treatment plants.

EPA's Water Quality Portal (WQP) aggregates monitoring data from federal, state, and tribal agencies. Polk County has limited coverage with 9 active monitoring sites with 5,151 recent measurements on record. Predominant monitoring categories include inorganics, minor, metals and physical. More monitoring sites generally indicate greater scientific attention to local water conditions — and provide the baseline data that regulators use to set future impairment listings.