Lake Ontario Canadian Nearshore Assessment, 2019 Highlights and Results Report

Executive Summary

The Great Lakes nearshore is a key priority for restoration and protection. These waters provide a source of drinking water for most communities within the basin, are the area where most human recreation occurs, and provide a critical ecological link between watersheds and the open waters of the Great Lakes.

While efforts to restore and protect the Great Lakes have been largely successful over the last 50 years, water quality and ecosystem health in many nearshore areas continue to be degraded due to a variety of human-, climate- and invasive species-induced stressors.

The Canada-U.S. Great Lakes Water Quality Agreement includes a commitment to develop an integrated nearshore framework in the Great Lakes that provides an overall assessment of the state of the nearshore waters. Nearshore assessments provide the basis for determining factors and cumulative effects that are causing stress or threatening nearshore areas of high ecological value.

In 2019, Canada conducted an assessment of the state of nearshore waters in Lake Ontario and the Niagara and St. Lawrence Rivers. The assessment classifies the Lake Ontario nearshore into Regional Units based on ecosystem type. The 2019 Highlights and Results Reports summarize the findings of cumulative stress across the 17 Regional Units of Lake Ontario’s nearshore.

Overall, nearshore areas in Lake Ontario are under moderate stress. The western portion of Lake Ontario – from the Niagara Peninsula to Pickering – is significantly more developed than the eastern portion and the St. Lawrence River. Many of the Regional Units are under high stress due to the extensive construction of shoreline stabilizing structures and numerous coastal barriers that impede erosion and sediment transport. Cladophora, a nuisance algae, washes up and fouls beaches and shorelines in the Burlington Beach to Humber Bay Regional Unit as well as much of the north shore from Pickering to the Kingston Basin. Additionally, harmful cyanobacteria was detected in the Hamilton Harbour, Bay of Quinte and Kingston Basin Regional Units, creating a concern to human and ecosystem health as well as high stress on nearshore waters.