Yavapai County, Arizona: drinking water report. Yavapai County in central Arizona has about 236,000 residents, with Prescott and Prescott Valley as the
Yavapai County in central Arizona has about 236,000 residents, with Prescott and Prescott Valley as the main population centers. The county relies almost entirely on groundwater from the Big Chino and Little Chino sub-basins and the Verde River watershed. Water scarcity is the overarching concern – the aquifer system is being drawn down faster than it recharges, and the county's growing population is competing with downstream water rights in the Verde Valley.
Arsenic contamination from natural geological sources affects Yavapai County wells. According to ADEQ's 2024 compliance data, five public water systems in the county have documented arsenic above 8 ppb, with two systems exceeding the 10 ppb MCL requiring treatment or blending. The Verde Formation and volcanic rocks underlying the county release arsenic into groundwater as it dissolves through the rock matrix.
Historic mining adds another layer. The county was one of Arizona's most active mining regions in the 19th and early 20th centuries. The Iron King Mine and Humboldt Smelter Superfund site in Dewey-Humboldt has documented arsenic and lead contamination in soil and groundwater. A 2024 EPA five-year review found arsenic at 180 ppb in monitoring wells near the site – 18 times the MCL.
Yavapai County's combination of natural arsenic, mining legacy, and declining aquifer levels means water quality may shift as wells draw from different zones over time. Regular testing is more important here than in areas with stable aquifer conditions.
Check your water for current results. For arsenic at any level, reverse osmosis is the most reliable treatment. Our water filter guide covers systems proven for desert groundwater. Get your detailed report for trends, and visit our Arizona page for statewide data.