LONG-TERM EFFECTS OF TREATED DOMESTIC WASTE-WATER ON BROWN TROUT

A 12-month bioassay was conducted to determine the effects of unchlorinated, treated, domestic wastewater on survival, growth, swimming performance, and gill tissue of brown trout (Salmo trutta). Ammonia was the toxicant of concern, because the facility's effluent periodically exceeded the U. S. Environmental Protection Agency's (EPA) recommended criterion. Juvenile brown trout (initial weight equals 2 g), which were exposed to six concentrations (0-37%) of effluent, were fed a restricted ration, so that growth rates were similar to those of wild stream residents. There were no significant effects of effluent concentration on survival, growth, or swimming performance of brown trout, but the degree of damage to gills was directly related to effluent concentration.