As Toxic Algal Blooms Impact Lake Erie, Michigan Sees Agriculture As Main Culprit

Jul 28, 2020

Toxic algae blooming in Lake Erie is creating safety concerns for humans and aquatic life prompting the state of Michigan to work with farmers to reduce the phosphorus levels in field runoff. 


Algal blooms have left parts of the Great Lake’s surface green, slimy and covered with scum. The scum is often found in areas with high levels of blue-green algae, or cyanobacteria. This bacteria produces cyanotoxins which can be harmful to humans and wildlife.

Other parts of the lake water may only be slightly green, but can still be just as toxic, said Craig Stow, a scientist at the National Oceanic and Atmospheric Administration’s (NOAA) Great Lakes Environmental Research Laboratory. 

“Just because you don’t see the scums, sometimes the water may just appear to be kind of an off-green color, it doesn’t mean those algae aren’t there,” Stow said. “Sometimes they’re just dispersed in the water and they may still be producing toxins or other nuisance kind of effects.” 

The factors that cause this toxicity are not well understood as algal blooms can also be green and slimy without being toxic and size has no effect, he said. 

Blooms appear in ecosystems that receive an excess of nutrients like nitrogen or phosphorus which the algae feed on.

Lake Erie faced the same issue in the 1960s and 70s, Stow said. Too much phosphorus was entering the lake in waste water from sewage treatment and industrial plants. The state took measures to reduce phosphorus levels in the late 70s, and conditions improved by the 1990s.

Then, the blooms returned, from a new source, in the 2000s.

“It seemed that we had fixed the problem in Lake Erie and we were good to go,” Stow said. "But as we’ve learned more we’ve recognized that they aren’t really broken or fixed. You can control a problem through management and that control has to be ongoing and may not have a clear end point.” 

The current algal blooms in Lake Erie have caused areas to turn green, slimy, and often foul smelling, making the water undesirable for activities like swimming and fishing. In some places, the cyanotoxins from blooms can impact the water quality in surrounding cities.  

Lake Erie's 2019 harmful algal bloom.
Credit Zachary Haslick, Aerial Associates Photography Inc.

The bloom occurs predominantly, but not exclusively, in western Lake Erie, Stow said. The size varies each year depending on the flush from the Maumee River, a main input of nutrients into the lake. 

This year NOAA has also spotted blooms in Sandusky Bay and further east in the central basin of Lake Erie. 

The main source of the phosphorus in Lake Erie is agricultural water runoff because of its common use in fertilizer, said James Johnson, the director of the Environmental Stewardship Division in the Michigan Department of Agriculture and Rural Development. 

“Phosphorus is a naturally occurring thing,” Johnson said. “Algae actually feed on phosphorus. Algae actually tends to be a very basic form of any healthy aquatic system, but too much algae actually ends up being a problem.”

Johnson helped write Michigan’s Adaptive Management Plan for Lake Erie. It was first referenced in 2018 as part of the larger guide towards making the lake a healthier ecosystem, the Lake Erie Domestic Action Plan

The adaptive management plan specifically identifies the steps Michigan departments will take towards reducing phosphorus levels and how they will collect and analyze data to adjust the course of action through repeated two year work plans.

Johnson says reducing phosphorus levels is a significant challenge because there are a lot of decisions that need to be made in agriculture, but the solution isn’t one size fits all. 

Each agricultural field is different, so they will need to work with growers field by field to implement Best Management Practices (BMPs) for each one. These are structural, vegetative or managerial practices used to reduce water pollution. 

And there are a lot of options. 

Some potential practices are changes in application and amount of applied nutrients, putting in grass waterways to cause nutrients to drop out of watershed and implementing reduced tilling practices so organic material like weeds grow on the surface of the field to slow the movement of water in rainstorms. 

End goals of the domestic action plan include reducing the total amount of phosphorus entering the lake from U.S. and Canadian watersheds by 40% and maintaining algae conditions similar to those seen in 2004 and 2012 which were not dominated by cyanobacteria. 

With how complex the solution to the algal bloom problem is, it may be difficult to reach these goals in five years time, said Michael Alexander the manager of the Surface Water Assessment Section of the Water Resources Division in the Michigan Department of Environment, Great Lakes and Energy. 

“We’re going to struggle to meet our goals by 2025,” Alexander said. “We’re hopeful that we can, between now and 2025, show a significant amount of progress in nutrient reduction and implementation of BMP’s and have a better understanding of how we can be successful and meet all of our goals, but it’s going to be difficult” 

Alexander also oversees public comment for the adaptive management plan. 

Public comment ended in June. The most common point brought up is the need to better specify and communicate the goals. The public wants more clarity on what practices will be implemented, and better documentation on watershed planning all the way down to the smallest scale, he said. 

The next steps in the process include responding to public comments directly and in a document to put online, re-drafting the adaptive management plan itself, beginning work on the first two year action plan and putting BMPs into place, Alexander said. 

The release date for the next draft has not been set. 

Taylor’s story is brought to you as part of a partnership between WKAR and Michigan State University’s Knight Center for Environmental Journalism.