Benton County Water Report

Benton County's water systems carry a failing grade, scoring 40.3 out of 100. Over the past five years, EPA SDWIS records 86 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 10.2% of assessed waterways carry an impairment designation (28 of 274 water bodies) across Benton County's watersheds. The leading impairment causes are dissolved oxygen - critical 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 2025-10-01T00:45:00.000-05:00) puts Illinois River South of Siloam Springs, AR at 584.0 cfs — running somewhat below its historical average at 82% 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. Benton County has moderate coverage with 35 active monitoring sites with 37,687 recent measurements on record. Predominant monitoring categories include physical and nutrient. 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.