Many of the contemporary environmental problems are geographic problems of spatial disparities between the distribution, impact, enforcement, costs, and remediation of a host of environmental ills. In order to link environmental process and human uses of the environment, a spatially accurate database of environmental hazards is required. This article examines the positional accuracy of some of the most important Environmental Protection Agency databases. It presents a methodology for identifying and correcting the errors found in the EPA databases, with South Carolina used as an example. Results show that more than 50% of the facilities in the state were initially located in the wrong census block group. The importance of this research for policy making is demonstrated with the use of an environmental equity analyses of a particular facility in South Carolina. © 1997 John Wiley & Sons, Inc.