Harmful algal bloom expected to be smaller

By Roger LaPointe - [email protected]

The western Lake Erie forecast for harmful algal blooms is predicting the bloom to be smaller for the third year in a row.

The National Oceanic and Atmospheric Administration’s National Centers for Coastal Ocean Science held the 11th annual forecast on Thursday, which was broadcast virtually and presented by Ohio Sea Grant and Stone Laboratory.

The 2022 forecast is predicting a 3.5 on the severity index, with a 2-4 likely range, according to Richard Stumpf, Ph.D., National Oceanic and Atmospheric Administration’s National Centers for Coastal Ocean Science.

“So it’s a forecast of 3.5, which is good overall. It would be better if it were 2 or 2.5, but at least we should be seeing smaller blooms and fewer scums as well. Scum does depend on a wind event. It’s definitely less than last year and closer to 2020. So I will say that most of the lake will be fine most of the time,” Stumpf said. “It takes a while to grow. The lake is warm now, so it should be growing through July. I expect by the end of July there will be some visible discoloration in the lake.”

Warnings and recommendations were issued related to the forecast.

Areas with a high concentration of algae have strong risk of scums during calm days. However, the bloom impact on the western basin of Lake Erie varies with wind. Generally, winds from south and west are best for Ohio, but not for Ontario, with calm winds being the worst.

The recommendation is to keep people and pets out of scums. The NOAA bulletin website gives current bloom locations and a scum forecast, which should be referenced before deciding to go into the lake.

“I can’t say this enough. The blooms create toxin,” Stumpf said. “Ohio does monitor for toxin level. We also do weekly updates, but scum can concentrate toxin at 10 to a hundred-fold or more. So please keep yourselves, your kids and your pets out of the water. Tragically, every year, a couple of dogs in this country die from having swum in lakes with these kinds of blooms, so please keep them out.”

Last year’s prediction was revised up from a low end of the range at 3 to closer to the 4.5 top end of the predicted range of severity. There was a moderate bloom, in total, which covered a large area, but at a lower concentration of algae.

“We don’t keep static with the models. They get adjusted,” Stumpf said.

Researchers stressed that the amount of rain, and when it happens, makes an impact on the size of the algal bloom.

This year, Western Lake Erie saw an average to somewhat below average discharge during the spring, with no major rainfall in June, or expected in July. The rainfall washes phosphorus into the lake.

“What I think is interesting for this year is that through June we had all these really interesting storm events, but they were really spotty. There were some counties that had flash flood warnings and cars were being washed away, while other counties were essentially entering a drought. I do have to wonder how that affects the other end of the watershed,” said Laura Johnson, Heidelberg University, National Center for Water Quality Research. “I think that kind of rain event is going to make it more difficult to detect the type of decreases we want to see.”

A drier spring meant a lower flow in the Maumee River likely resulting in less phosphorus fertilizer runoff into Lake Erie.

“What I think has happened is we have gone through one of these wet cycles, but superimposed is this climate factor, where heavier rains are making more of a discharge, so our baseline is changing,” Stumpf said. “I think we are going to see fewer low-flow years … because if each time it rains it is an inch of rain, rather than a half and inch, you end up with more discharge.”

The period of time from 2008 to 2017 is now being seen as a high rain concentration time.

“What this means is we’ve got to get the concentrations down,” Stumpf said. “So when we have a next large flow year, we don’t have a bloom to Cleveland.”

The index is based on the bloom’s biomass – the amount of algae – during the peak 30 days of the bloom. An index above 5 indicates more severe blooms. Blooms over 7 are particularly severe, with extensive scum formation and coverage affecting the lake.

The index uses multi-spectral bloom data based on the color of the water surface. That data is collected by both of the European Union’s Copernicus Sentinel-3a satellites.

The toxicity level of the 2014 harmful algal bloom prompted a shutdown of the Toledo water system for more than 400,000 people during two days at the peak of the bloom, resulting in an estimated $65 million total economic loss. Among those customers were some Fulton County residents.

The leading source of bloom growth is phosphorous, found primarily from various forms of farming activity.

Researchers said that the H2Ohio program is starting to work. Research has shown that farmers are putting less phosphorus on the fields, using better practices and wetlands are being created.

Lake Erie blooms of blue-green algae, also called cyanobacteria, are capable of producing the liver toxin microcystin. Presence of the toxin prevents people from fishing, swimming, boating and visiting the shoreline, and harms the region’s summer tourism economy.

By Roger LaPointe

[email protected]