Lake Erie algal bloom season proving to be mild in 2020

PORT CLINTON - For Ottawa County Sanitary Engineer Kelly Frey, this year's harmful Lake Erie harmful algal bloom (HAB) season has been the exact opposite of 2019.

That's good news so far for Frey and the Ottawa County Regional Water Treatment Plant, with a subdued bloom meaning less of a threat to the region's drinking water supply.

Researchers predicted in July western Lake Erie's harmful algal blooms would reach 4.5 on the NOAA severity index, a relatively mild season compared to 2019's 7.3 on an index of 1-10.

Frey said this spring's lack of rainfall has been a significant factor.

"We didn't have the high levels of phosphorus coming off the fields," Frey said Friday.

There has been some expansion of a bloom in Maumee Bay in recent weeks.

NOAA's Lake Erie harmful algal bloom forecast, updated Friday, reported a bloom of microcystis cyanobacteria continuing in the western basin of Lake Erie, with eastward transport of the bloom being observed.

The bloom is present in Maumee Bay, extending north along the Michigan coast to Brest Bay, along the Ohio coast towards the Portage River, and offshore to the Bass Islands.

According to the forecast, sampling conducted Aug. 4 indicated toxin concentrations had increased but remained below the recreational threshold at all locations. 

At the peak of the 2019 summer's season for harmful algal blooms on Lake Erie, the Ottawa County Regional Water Treatment Plant's raw water intake produced a sample microcystin reading of 22 parts per billion.

It's recommended that humans have no contact with water containing a microcystin reading of 20 ppb.

Frey said that sample, taken Aug. 12 of last year, was the highest recorded by the water treatment plant in 2019 and higher than anything he'd seen in other Ohio water treatment plants in the western Lake Erie basin.

So far in 2020, there have no recorded microcystin detection at the water treatment plant.

Frey said the lake's turbidity is the lowest he's seen in a long time, with visitors able to see the bottom of the lake in some spots.

He said that, while there have been occasions where there's been later bloom expansions in the summer, he's happy with how this HAB season is trending and called the treatment plant's water quality "superb."

The NOAA HAB severity index is based on the bloom's biomass — the amount of algae — over a sustained period.

The largest blooms occurred in 2011, with a severity index of 10; and 2015, at 10.5. NOAA, the Environmental Protection Agency, Environment and Climate Change Canada and its other partners have set a goal of 3, which was last seen in 2012. 

Anything over 5 indicates a severe bloom. 

The 2018 bloom measured a 3.6 on the HAB severity index.

dacarson@gannett.com

419-334-1046

Twitter: @DanielCarson7