Beginning in Hay of 1969 field surveys have been conducted in the Hog Island area of the James River to characterize the biota of the region. The objective of these surveys has been to determine any significant changes in the biota related to the operation of the nuclear power station. Although during the period of study, methods and stations have been changed to adjust the study to changing regulations, its basic character has remained. Communities surveyed have included benthos, epibenthos, zoo- and phytoplankton, fish, and fouling organisms. In addition, special studies of thermal tolerance have been conducted on oysters and Rangia clams. During this study period an additional aspect was added when entrainment studies to determine zooplankton mortality when entrapped in the thermal plume were initiated