A multi-institution study led by the University of Michigan concludes that significant changes to agricultural practices will be required to meet the agreed-upon goal of reducing levels of algae-promoting phosphorus in Lake Erie by 40 percent in order to effectively reduce Harmful Algal Blooms.

The study, “Informing Lake Erie Agriculture Nutrient Management via Scenario Evaluation,” (PDF) was published by the University of Michigan Water Center. It incorporates results from six modeling teams representing various research institutions.

For lead author and ecologist Don Scavia, the study results present an implausible scenario for effectively addressing the nutrient load concerns.”Our results suggest that for most of the scenarios we tested, it will not be possible to achieve the new target nutrient loads without very significant, large-scale implementation of these agricultural practices.” Scavia overseas the Water Center as director of the Graham Sustainability Institute. “It appears that traditional voluntary, incentive-based conservation programs would have to be implemented at an unprecedented scale or are simply not sufficient to reach these environmental goals, and that new complementary policies and programs are needed.”

The research team combined various nutrient load management options into 12 scenarios that were each tested using six computer models. Accordingly, “the watershed models tested the ability of each scenario to achieve the proposed 40 percent phosphorus-reduction target. The scenarios examine both the total amount of phosphorus, known as TP, and the amount of dissolved reactive phosphorus (DRP), the form of the nutrient that is most stimulating to algae.”

More or less, the potential scenarios tested represented very improbable situations coming to fruition. Even then, seven of the 12 tested management programs were unable to meet the required reduction threshold. The others required significant nutrient management programs affecting thousands to 10s of thousands of farms. Farming practices must change. But can they?

Even so, the research is of vital importance to understanding a growing problem in the Lake Erie region that represents significant health and infrastructure risks to neighboring communities that rely on water from Lake Erie: see the 2014 contamination of Toledo’s water supply that affected the drinking water of nearly 400,000 citizens over several days.

Other than Scavia, the research team and study authors consisted of Scott Sowa of The Nature Conservancy; U-M’s Margaret Kalcic, Rebecca Logsdon Muenich, Jennifer Read and Yu-Chen Wang; Jay Martin, Noel Aloysius, and Marie Gildow of Ohio State University; Chelsie Boles, Todd Redder and Joseph DePinto of LimnoTech; Remegio Confesor of Heidelberg University; and Haw Yen of Texas A&M University.

Photo credit: Dr. Tom Bridgeman, Univeristy of Toledo