Review of potential ecological impacts from winter drawdown scenarios in Lake St. Lawrence

Winter operations of the Moses-Saunders Dam (St. Lawrence River) in accordance with direction from the IJC’s International Lake Ontario – St. Lawrence River Board (ILOSLRB) have historically resulted in a large drawdown in water levels on Lake St. Lawrence (the forebay for the hydropower structures) during winter months. Given ongoing high water levels on Lake Ontario and the upper St. Lawrence River, the ILOSLRB is looking at further increasing outflows during the winter months in an effort to reduce near record-high Lake Ontario water levels. Such an increase in outflows could result in further water level drawdown on Lake St. Lawrence during the winter months. The goal of this project is to fill a knowledge gap regarding the potential ecological impacts of greater than normal winter drawdown on Lake St. Lawrence through the production of a current literature review of the potential ecological effects of winter drawdowns associated with hydroelectric dam operations, and conducting a GIS-based sensitivity analysis of lower water level scenarios in Lake St. Lawrence. This initial effort would also identify areas potentially requiring further field investigation in the future.  This project is also highlighted in our IWI projects StoryMap here.