Buffalo County Water Report

Buffalo County earns a B grade for drinking water quality, scoring 67.1 out of 100. Over the past five years, EPA SDWIS records 1 health-based violation — a single incident worth monitoring.

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 large majority — 60.0% — of assessed waterways are impaired (9 of 15 water bodies) across Buffalo County's watersheds. The leading impairment causes are mercury in fish tissue and escherichia coli (e. coli). 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 2026-05-14T13:45:00.000-05:00) puts South Loup River at 152.0 cfs — running somewhat below its historical average at 66% 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. Buffalo County has moderate coverage with 21 active monitoring sites with 9,953 recent measurements on record. Predominant monitoring categories include physical and habitat. 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.