In mid-1987, an informal telephone survey of National Pollutant Discharge Elimination System (NPDES) State and EPA Regional personnel was conducted to determine the current use of effluent biological testing. Regions and States were asked the number of NPDES permits they administered, the number of permits with a biological toxicity testing requirement, the number of permits with expressed toxicity limits and with requirements for toxicity reduction evaluation. Regional and State programs were discussed, including the use of biological testing such as acute and chronic toxicity testing techniques, instream biotic assessments, water quality trend monitoring at fixed locations, and aquatic organisms flesh analyses for bioaccumulative materials, as well as any other use of biological investigative techniques.