As analytical methods and technologies continue to improve@ and trace concentrations of pollutants in ambient waters are better quantified@ regulatory agencies are increasingly setting effluent permit limits for some pollutants near analytical detection limits@ and establishing policies for determining compliance with these stringent limits. The American Petroleum Institute (API) conducted a review of state policies related to analytical detection and quantification limits@ with particular focus on water quality and wastewater issues in permitting and compliance. Of the ten states considered in this review@ every state was found to incorporate detection or quantification terms in its regulations to some extent. Some of the states prefer to have the most detailed policies in their water quality implementation procedures; other states prefer to put the detail directly in the regulations. Most of the states specify@ either in their regulations or implementation procedures@ how compliance is demonstrated. Permittees can ensure that they obtain permit limits that do not cause compliance monitoring problems by paying particular attention to effluent data during the permit application process@ by identifying early in the permitting process the need for site-specific detection and quantification limits@ and by understanding the state's permit requirements and policies specifying how compliance is to be demonstrated.