Direct environmental regulation has been in place in the United States for more than twenty-five years. Yet there has been little study of what actually affects regulatory enforcement levels. This study examines enforcement issues by focusing on water quality enforcement by the Louisiana Department of Environmental Quality. The study finds that penalties are more likely to occur, and are likely to be higher, the more serious a firm's violation of a regulation. Penalties are also more likely, and likely to be higher, if a firm has a previous record of environmental violations. In contrast to other studies, however, we do not find that enforcement varies across regional offices. In addition, we did not find any systematic effects of the Weingast and Moran (1983) theory of legislative dominance. We did, however, find evidence of rent extraction, along the lines of McChesney (1987; 1991).