Groundwater Protection: The Use of Drinking Water Standards by the States

In response to a congressional request, GAO examined whether Environmental Protection Agency (EPA) drinking water standards were appropriate for use as groundwater standards, specifically: (1) whether states relied on EPA standards when setting numeric groundwater standards; (2) states' use of existing numeric groundwater standards in their groundwater protection programs; (3) the potential for groundwater quality degradation using drinking water standards; and (4) how drinking water standards compared to guidelines for protecting uses of groundwater for such purposes as irrigation, livestock watering, and aquatic life.