Great Lakes researchers forecast harmful algal bloom coming for Lake Erie this summer

It's not just your Great Lakes water levels that are reaching extreme measures these warmer months. Researchers from several universities, including the University of Michigan are forecasting a harmful algal bloom in Lake Erie this summer.

"Because of the excessive spring precipitation, this year's bloom is likely to be large," said Don Scavia, a University of Michigan aquatic ecologist in a news release.

Researchers measure bloom events on a severity index that usually ranges from 1 to 10. For notable bloom events in 2011 and 2015, the severity index was at 10 and 10.5 respectively. The toxins contaminated drinking water for the thousands of people that live near Lake Erie.

While 2019's bloom isn't expected to reach those extremes, it has a predicted index of 7.5, and could go as high as 9. An index measure is based on how much biomass - or algae - is in the bloom, and for how long.

Every bloom event is unique and 2019's will be no different. One of the key factors impacting the bloom this year is the amount of rain that has fallen. Jennifer Read, the director of the University of Michigan Water Center said some farmers didn't apply as much fertilizer in the fall and spring because of how much it rained. 

This means that not as much fertilizer - which contains nutrients like phosphorus that promote algal blooms - ran off into the river. 

"The concentration is lower because there is less phosphorus in the water," Read said. "Because crops didn't come off until late, that delayed activity. Spring was (also) late, so it affected their regular flow on land."

That doesn't mean a bloom event can't happen, however.

"Even though we saw a reduction in phosphorus, there's still a lot in the water. It's still coming from farm fields, still coming from other activities," said Read.

Harmful algal bloom (HAB) events are caused by an infusion of nutrients into a body of water. When fertilizers containing phosphorus work their way into the water via runoff or other means, it encourages rapid growth of algae. 

That algae can harm the ecology in the water, as well as be deadly to the health of humans. The contaminated water needs to be treated by local municipalities and city governments, which costs administrations millions of dollars. 

Many of the nutrients that find their way into Lake Erie come from the Maumee River watershed - an agriculturally dominated landscape where runoff can make its way into the water.

Researchers anticipate this year's bloom starting later than usual - near the end of July. Due to the pervasive rainfall this year, the lake's temperatures aren't as warm as they usually are. Last year's event - which only reached an index of 3.6 - started sooner due to exceptionally warm weather at the beginning of June.

How this impacts the lake's users remains to be seen. Blooms can be dynamic and move around. Jennifer Read said one beach could be releasing toxins while another is just clean. For an updated summary of Lake Erie's coastline, check out the HAB bulletin here.

As states continue mitigating bloom events, researchers have made progress in better understanding the dynamics of algal blooms, including how the biomass moves and the toxin production that occurs.