Mohave County Water Report

Mohave County's water systems carry a failing grade, scoring 26.2 out of 100. Over the past five years, EPA SDWIS records 184 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 small share — 3.3% — of assessed waterways are impaired (1 of 30 water bodies) across Mohave County's watersheds. The leading impairment cause is ammonia-nitrogen. 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 2026-05-14T11:30:00.000-07:00) puts COLORADO RVR ABV DIAMOND CREEK at 7.5k cfs — well below its long-term average at 56% 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. Mohave County has extensive coverage with 141 active monitoring sites with 33,713 recent measurements on record. Predominant monitoring categories include organics, other 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.