An examination of the epifauna collected on fifty fouling panels was made to determine the influence of the thermal discharge from the Waiau Steam-Electric Generating Station on these organisms. Many of the organisms were found to differ significantly in abundance, biomass and percent cover between the thermally affected and non-affected areas. Three species clusters or communities were identified on the panels which correspond to intertidal, subtidal thermally affected, and subtidal non-thermally affected communities. The latter are roughly separated by the 3°C isotherm of temperature above ambient which corresponds to a summer maximum of approximately 32°C.