WHAT HAPPENS WHEN LAKE LEVELS ARE REGULATED?

Lake Ontario water levels have been regulated since the St. Lawrence Seaway began operation in 1960. Lake levels are largely controlled by releases from the Moses Saunders Power Dam on the St. Lawrence River. The range of fluctuations under regulation Plan 1958DD was compressed from about 1.5m to 0.7m. More than 50 years of regulation resulted in broad-scale invasion of plant communities in Lake Ontario wetlands by cattails and loss of sedge/grass meadow at higher elevations because low lake levels that gave a competitive advantage to sedges and grasses were eliminated. The reduced range of fluctuations also resulted in expanded shoreline development. Shoreline processes were also altered, which included concentrating wave-attack during storms on a narrower elevation range. Shorelines were armored, and shoreline processes were altered further. In January 2017, following 15 years of bi-national studies, evaluations, and public meetings, the U.S.-Canadian International Joint Commission implemented new regulation Plan 2014. This plan attempts to restore environmental protection by increasing the range of fluctuations and returning a more natural, quasi-periodic pattern of fluctuations dictated by differences in annual total water supplies to the lake. However, the plan contains provisions to allow intervention by the Control Board to reduce extreme high and low lake levels and flows in the river that could have adverse impacts on other constituent interests–shoreline property, hydropower, shipping, recreational boating, and municipal/industrial water intake. Extreme snow-melt and precipitation during spring and early summer 2017 resulted in water supplies that did not allow Lake Ontario water levels to be reduced without causing further damage to already-flooded downstream Montreal. Shoreline property owners falsely blamed the new regulation plan, and controversy continues, as low water supplies and low lake levels that potentially could restore beaches are awaited.