Over the summer period December 1997/January 1998, a program of field work was undertaken as part of a research project to develop numerical models of the wastewater discharge systems entering the marine waters off Casey Station in Antarctica. Samples were evaluated for ammonia, total phosphorus, and four categories of bacteria of the study period , and levels compared with the wastewater treatment plant influent and effluent, and marine background levels. Elevated levels of all parameters measured were found in the vicinity of the discharge, an area frequented by penguins from the nearby rookery. Dilution factors were calculated for esch of the three parameters and range from 4 for phosphorus to 600 for bacteria. The study also found that levels of the three measured parameters increased as the air temperature increased due to accelerated melting of the snow and ice through which the wastewater flows before entering the marine environment.