Hydrodynamics and Its Impact on Water Quality Management in the Northern Nearshore of Lake Ontario

Session: 31. - Evaluation of the Current State of Ecological Modeling and Future Perspectives

Chenfu Huang, Michigan Technological University, [email protected]
Anika Kuczynski, National Institute of Water and Atmospheric Research, [email protected]
Martin Auer, Dept. of Civil Engineering, Michigan Techn. University, [email protected]
Pengfei Xue, Michigan Tech, [email protected]

Abstract

The Greater Toronto Area (GTA) on the northern shore of Lake Ontario is home to nearly 6 million people relying on the lake as a source of drinking water and a location for waste disposal.  Renewed interest in the nearshore focuses on cases where receptors are impacted by previously unattended and emerging pollutants of concern.  The spatiotemporal pattern of an effluent plume is significantly influenced by multiscale hydrodynamics. Here, we apply a 3-D hydrodynamic model at several sites where the effluent plumes from municipal wastewater treatment plants are juxtaposed with Cladophora (nuisance algae) habitat. Results show that the plumes are highly dynamic in both time and space. The size of the wastefield footprints depends on chosen threshold contaminant concentrations and should be carefully assessed by comparison of model simulation results and observational data.  We find that the standard effluent discharge/receptor dilution ratio applied to manage conventional pollutants such as ammonia does not hold for managing the phosphorus/Cladophora dynamic, when using open lake phosphorus concentrations as the no-impact baseline reference.

1. Keyword
Lake Ontario

2. Keyword
hydrodynamic model

3. Keyword
lake management