Lagoon Wastewater Effluent Impacts Stream Metabolism in Red River Tributaries

Abstract

Lagoons are the most common form of sewage treatment for rural Canadian communities and may therefore be a major source of pollution to local waterways. However, the environmental effects of pulse releases of lagoon effluent are largely unknown. This study reports on changes in physicochemical conditions and stream metabolism occurring as result of summer lagoon effluent releases into Red River tributaries, Manitoba, Canada. We calculated metrics of stream metabolism using the single-station, open water method. We found that an effluent release results in a significant short-term increase in physicochemical (i.e., water nutrients, stream discharge) conditions which had a subsidy effect on stream metabolism. We also found that stream metabolism was significantly greater in effluent exposed versus unexposed reaches; however, our results suggest the degree of effect depends on whether the release occurred early or late in the summer. The findings of this study have implications for lagoon management and future stream monitoring projects aimed at evaluating the effects of lagoon wastewater effluent