Abstract

Ground water provides 100 percent of Iron County’s potable water, therefore protection of this resource is critical. Drinking-water source-protection guidance is provided by the State of Utah, Department of Environmental Quality, Division of Drinking Water. Source-protection zones for public water systems in Iron County were delineated as follows: Zone 1, the 100-foot radius around the wellhead or spring; Zone 2, the 250-day ground-water time of travel to the source; Zone 3, the 3-year time of travel; and Zone 4, the 15-year time of travel. Ground-water sources and their corresponding protection zones were collated, digitized, and mapped for the County. Cedar Valley is the most populous area in the County. The principal aquifer is the unconsolidated and semi-consolidated Quaternary and Tertiary basin fill. Contaminant inventories within the protection zones indicate that the primary potential sources of contamination are onsite wastewater disposal systems (septic tanks and leach fields) and agricultural practices (livestock and agricultural chemicals). Although recent data indicate that elevated nitrate levels in some parts of Cedar Valley may be natural, septic systems represent the largest reported cause of ground-water contamination resulting in disease outbreaks in the United States. The source-protection zones established for public water systems are obvious areas in which to limit current and future practices that may lead to ground-water contamination. Recharge areas, primarily along the valley margins where the basin fill is coarse and unconsolidated, are also areas recommended for protection.