Dunn County Water Report

Dunn County's drinking water received a D grade, scoring 48.2 out of 100. Over the past five years, EPA SDWIS records 4 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 17.8% of assessed waterways carry an impairment designation (49 of 276 water bodies) across Dunn County's watersheds. The leading impairment causes are phosphorus, total and polychlorinated biphenyls (pcbs). 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 RED CEDAR RIVER at 1.2k cfs — running somewhat below its historical average at 89% of mean. 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. Dunn County has extensive coverage with 133 active monitoring sites with 17,163 recent measurements on record. Predominant monitoring categories include physical and organics, pesticide. 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.