This study was designed to evaluate ambient toxicity in the Chesapeake Bay watershed by using a battery of water column and sediment toxicity tests in concert with both fish and benthic community assessments. A team of scientists from two Chesapeake Bay research laboratories, Maryland Department of Natural Resources and Versar Inc. worked jointly to complete this goal. Water column toxicity studies and overall project management were directed by Lenwood W. Hall, Jr. of the University of Marylands Wye Research and Education Center. Sediment toxicity tests and water/sediment chemical analysis were managed by Joe Winfield of Old Dominion Universities Applied Marine Research Laboratory. Margaret McGinty of Maryland Department of Natural Resources was responsible for the fish community assessments and Roberto Llanso of Versar Inc. conducted the benthic community assessments. Raymond Alden was responsible for the water and sediment index calculations. This report summarizes data from the ninth year of a nine-year ambient toxicity testing program. The U. S. Environmental Protection Agencies Chesapeake Bay Program Office supported this study.