Representatives from the United States Environmental Protection Agency and Environment and Climate Change Canada presented on the ongoing efforts to manage excess phosphorus loads leading to toxic and nuisance algal blooms and hypoxia in Lake Erie. The webinar provided a brief overview of information and updates on work under the Nutrients Annex of the Great Lakes Water Quality Agreement (GLWQA) and included presentations by experts from the Nutrients Annex Subcommittee.
Under the Great Lakes Water Quality Agreement, the U.S. and Canada, with the Lake Erie states and province, have agreed to work together to reduce the amount of phosphorus entering the western and central basins of Lake Erie by 40 percent (from 2008 levels). ErieStat will track progress toward this goal and support the Annex 4, Nutrients, Subcommittee convened under the Water Quality Agreement. The governments of Michigan, Ohio, and Ontario have further agreed to achieve the reductions for the western basin by the year 2025 with an aspirational goal of a twenty percent reduction by 2020.
Download the ErieStat fact sheet here.
Harmful Algal Blooms (phosphorus in the spring)
Total and soluble reactive phosphorus (SRP) are tracked in the spring period of March-July to measure progress at eight priority tributary watersheds identified as contributors to harmful algal blooms in the western basin.
ErieStat presents information as both loads (the total amount of phosphorus entering the lake from a tributary) and flow weighted mean concentration (FWMC) – which standardizes the measure of phosphorus delivery from a tributary so that performance can be compared across years and tributaries despite different flows.
For example, in a dry year the load may be low due to less runoff, but the FWMC will still be high if the phosphorus concentration in that runoff is high.
Hypoxia (annual phosphorus)
Modeling suggests that annual total phosphorus loads influence the extent and intensity of hypoxia (low oxygen) in the central basin.
- Limiting the annual total phosphorus load is thought to raise the oxygen concentrations in the bottom waters of Lake Erie to an acceptable level.
- The annual total phosphorus load is tracked at ten priority tributaries and also estimated for the entire western and central basin.
The Great Lakes Sediment and Nutrient Reduction Program (GLSNRP) provides grants to local and state governments and nonprofit organizations to install sediment and nutrient control practices in the Great Lakes Basin. Projects funded under the program are selected on a competitive basis and benefit the Great Lakes states.
The Ohio Environmental Protection Agency (Ohio EPA) has assisted in the establishing a comprehensive/continuous water quality monitoring network specific to tracking progress toward meeting the Ohio Domestic Action Plan and Annex 4 goals.