Abstract

Eutrophication is the over-enrichment of nutrients. It has become a leading cause of lake pollution. The gathering of nutrients in lakes is influenced by human activities, including the disposal of domestic wastewater and other waste effluents. This introduces an overabundant nutrient loading into lakes and intensifies eutrophication. In a eutrophic lake, species diversity decreases, dissolved oxygen contents deplete, and aquatic animals and plants die out, eventually leading to an ecosystem collapse. The purpose of this study is to improve our understanding of the impacts of domestic wastewater disposal on lake water quality. This study takes the approach of numerical simulations to predict the transport, diffusion, and degradation of water pollutants in a lake. The simulations are performed using the Environmental Fluid Dynamic Code (EFDC). The site of study is Lake Caron in Quebec, where periodic eutrophication occurs due to the discharge of untreated sewage. The scope of work includes an analysis of the responses of the lake water to the nutrient loading. The simulations consider seven parameters, including chlorophyll a, dissolved oxygen, chemical oxygen demand, carbonaceous biochemical oxygen demand, nitrate nitrogen, ammonia nitrogen and total phosphorus. The results capture hydrodynamics and water quality processes in Lake Caron. The results show spatial and temporal variations in the concentrations of pollutants, suggesting that the nutrient-rich wastewater can trigger nuisance algal blooms and deteriorating water quality. This study demonstrates the efficiency and effectiveness of the EFDC model. The simulation methods from this study can be applied to other lakes for the investigation of eutrophication.