Ecological assessments of effluent impacts on communities of indigenous aquatic organisms [electronic resource] / a symposium sponsored by ASTM Committee D-19 on Water, American Society for Testing and Materials, Ft. Lauderdale, Fla., 29-30 Jan. 1979, J. M. Bates, Ecological Consultants, Inc., and C. I. Weber, U.S. Environmental Protection Agency, editors