"EXECUTIVE SUMMARY The U.S. Environmental Protection Agency (EPA) is currently developing a water quality-based approach to permit limitations for toxics and nonconventional pollutants. In February 1984@ EPA issued a National Policy on the regulation of discharges of toxic pollutants. Also@ EPA has released a draft guidance document (July 1984) entitled ""Technical Support Document for Water Quality-Based Toxics Control."" The Agency's guidance encourages the use of bioassays on whole effluents to assess acute and chronic toxicity. To predict chronic effluent effects on freshwater@ estuarine@ and marine organisms@ EPA is recommending the use of short term chronic tests@ sometimes called ""rapid chronic"" bioassays. This report identifies and evaluates ""rapid chronic"" bioassays suitable for assessing whole effluent toxicity. The first section is a review@ evaluation@ and ranking of freshwater@ estuarine@ and marine ""rapid chronic"" bioassays. The second section is a statistical and biological evaluation of two recently developed freshwater ""rapid chronic"" bioassays--a 7-day survival and reproduction test with the cladoceran@ Ceriodaphnia reticulata@ and a 7-day survival and growth test with the fathead minnow@ Pimephales promelas."