Utah's Groundwater-Quality Classification Program

     Groundwater-quality classification, also called aquifer classification, is a tool developed by the Utah Division of Water Quality for local governments to use for managing potential groundwater-contamination sources and protecting the quality of their groundwater resources.  The Utah Ground Water Quality Protection Regulations contain a provision allowing the Utah Water Quality Board to classify all or parts of aquifers as a method for maintaining groundwater quality in areas where sufficient information is available.  This includes having a comprehensive understanding of the aquifer system supported by factual data for existing water quality, potential contaminant sources, and current uses of groundwater.  Aquifer classification (or reclassification) may be initiated by either the Utah Water Quality Board or by a petition prepared under the direction of a licensed professional geologist or licensed professional engineer.  The Utah Geological Survey has prepared most of the groundwater-quality classification petitions thus far approved by the Utah Water Quality Board. 

     Utah’s groundwater-quality classes are based mostly on total-dissolved-solids (TDS) concentrations as follows:  Class IA (Pristine), less than 500 mg/L; Class II (Drinking Water Quality), 500 to less than 3,000 mg/L; Class III (Limited Use), 3,000 to less than 10,000 mg/L; and Class IV (Saline), 10,000 mg/L and greater.  If any contaminant exceeds Utah’s groundwater-quality (health) standards (and, if human caused, cannot be cleaned up over a reasonable time period), the groundwater is classified as Class III, Limited Use groundwater. 

     By following guidelines developed by the Utah Division of Water Quality, our studies have delineated all four classes of groundwater quality in various basin-/valley-fill aquifers in Utah.  However, most areas contain groundwater classified as either Pristine or Drinking Water Quality, the higher quality categories established under the Utah Water Quality Board’s classification system.