Current (1993) national standards and guidelines pertaining to pesticide contaminants in water, bed sediment, and fish and shellfish tissues are summarized to provide a condensed reference source for definitions and current values applicable to pesticides in aquatic environmental media. This report facilitates comparison of measured concen- trations of pesticides in environmental samples with applicable standards and guidelines. For each standard or guideline, the following is provided: (1) Definition, including the underlying assumptions and mathematical derivation; (2) originating agency; (3) statutory authority; (4) regulatory status and, for standards, the agency responsible for enforcing the standard; (5) applicable sampling medium; (6) beneficial use and resource protected, and (7) full citations of published documentation. The report emphasizes the appropriate application on national standards and guidelines to water-quality data on pesticides to aid in assessing potential adverse effects on human health, aquatic organisms, and wildlife. (USGS)