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Western Lake Erie Basin

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Western Lake Erie Basin

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What’s Happening in Lake Erie?

The western part of Lake Erie, also known as the Western Lake Erie Basin (WLEB), experiences seasonal harmful algal blooms (HABs). These blooms can contain toxins that are harmful to humans, pets, and aquatic organisms. 

The HABs are made up of cyanobacteria (blue-green algae) that need sunlight, warm water temperatures, and nutrients, such as phosphorus and nitrogen, to grow and produce toxins. Nutrient-rich water from wastewater treatment plants and farm fields, the effects of invasive species that increase water clarity, water temperatures over 70°F, and other factors can cause the HABs to grow. 

Though the causes are complex, the State of Michigan is committed to improving the water quality of Lake Erie, ensuring safe water, and supporting healthy ecosystems. Michigan’s portion of the WLEB covers watersheds in four Michigan counties (Hillsdale, Lenawee, Monroe, and Washtenaw). Michigan is planning and implementing conservation practices to improve soil health and water quality in the region. 

Algal bloom in a lake, caused by the bluegreen alga Microcystis A picture of an algal bloom.

Sources of Phosphorus

The state has developed tailored approaches to addressing point and nonpoint sources of phosphorus. The chart below identifies, defines, and provides examples of these two sources.  

Point Sources Nonpoint Sources
Come from specific, identifiable locations, allowing for easier monitoring and regulation Come from across the entire landscape, making monitoring and regulation more difficult
Examples: wastewater treatment facilities, concentrated animal feeding operations Examples: fertilizer runoff, soil erosion

An example of point source of phosphorus. A wastewater treatment facility.

Wastewater treatment facility. Credit: Great Lakes Water Authority

An example of nonpoint source of phosphorus. Soil erosion.

Soil erosion. Credit: Natural Resources Conservation Service
Chart provided/credit by: Michigan’s Lake Erie Domestic Action Plan Update (PDF)
A map showing the WLEB watersheds in Michigan, Ohio, and Indiana. The watersheds are named after the major bodies of water that flow into Lake Erie. Michigan’s watersheds cover the River Raisin, and the upper portions of the Ottawa-Stony, Tiffin (called Bean Creek in Michigan), and the St. Joseph River. A map showing the WLEB watersheds in Michigan. The watersheds are named after the major bodies of water that flow into Lake Erie. Michigan’s watersheds cover the River Raisin and the upper portions of the Ottawa-Stony Watershed, Bean Creek (called Tiffin River in Ohio), and the St. Joseph River that are part of the Upper Maumee River Watershed in Ohio.

Addressing Water Quality in Michigan’s Portion of the WLEB

In May 2025, the State of Michigan released an update to its Domestic Action Plan (DAP) for combating harmful algal blooms in western Lake Erie. 

The DAP contains measures to reduce the phosphorus loading into the WLEB that drives algal blooms. The goal is to achieve a sustained 40 percent reduction over a baseline measurement taken in 2008. The Michigan Departments of Agriculture and Rural Development (MDARD); Environment, Great Lakes, and Energy (EGLE); and Natural Resources (DNR) review and revise the DAP approximately every five years based on progress and changing needs in the region. The DAP was originally created in 2018 following adoption of the targets in 2015 set through the Great Lakes Water Quality Agreement. 

The departments also created the 2021 Adaptative Management Plan (AMP), which is a companion document to the DAP. The AMP is a management tool used to evaluate the success of the projects outlined in the DAP and update those projects as needed to meet water quality goals. 

Western Lake Erie Basin Program

In Fiscal Year 2022, the Michigan Legislature appropriated $25 million in one-time general funds to MDARD (Michigan Public Act 87 of 2021) for a five-year (2022 through 2026) Agricultural Nutrient Best Management Voluntary Practices Pilot Program (also known as the WLEB Program).  The WLEB Program focuses on water quality improvements. Funds may be expended for any of the following: grants, cost sharing, or other incentives towards the implementation of priority practices; soil or water quality testing; associated equipment and structures; technical support; and/or  education, outreach, and training.

View the full list of projects in the DAP.

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