To help manage nutrient loads and mitigate the impacts of harmful and nuisance algae in Lake Ontario, the United States and Canada committed, through the 2012 Great Lakes Water Quality Agreement (GLWQA), to review (and revise if appropriate) the binational phosphorus targets for Lake Ontario. Based on the findings of a recent assessment, the GLWQA Nutrients Annex Subcommittee recommends that the interim substance objective for Total Phosphorus concentration in open waters and interim Total Phosphorus load target for Lake Ontario should not be revised at this time.
ECCC and U.S. EPA have committed to conducting engagement to share findings from the assessment and to receive feedback from partners.
Comments will be accepted until August 30, 2023 and will be used in consideration in the development of a final recommendation to the Great Lakes Executive Committee by the end of 2023.
In 2020, the Nutrients Annex Subcommittee established the Lake Ontario Objectives and Targets Task Team to conduct a scientific assessment to determine whether the interim binational phosphorus substance objective for Total Phosphorus concentration and load target for Total Phosphorus for Lake Ontario should be revised. The Task Team represented diverse perspectives from a range of fields, including limnology, modelling, food web ecology, fisheries science, and natural resource and watershed management. The Task Team completed its assessment and submitted their recommendations to the Nutrients Annex in September 2022.
In Canada, please direct any questions or comments to glwqa-aqegl@ec.gc.ca.
In the United States, please direct any questions or comments to glwqa@epa.gov.
The following infographic outlines the Nutrients Annex Subcommittee’s recommendation:
- Assessing Phosphorus Targets for Lake Ontario (PDF 1.86 MB)