After wet spring, NOAA predicts large algal bloom on Lake Erie

GIBRALTER ISLAND — Despite a minimum of crops being planted this spring, the National Oceanic and Atmospheric Administration and its research partners are forecasting a “significant” harmful algal bloom this summer on Lake Erie.

This year’s bloom is expected to measure 7.5 on the severity index, but could range between 6 and 9. An index above 5 indicates blooms having greater impact.

The severity index is based on a 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. Last year’s was 3.6, while 2017’s was 8.0.

The expected bloom severity was announced Thursday during an annual get-together at Ohio State University’s Stone Lab on Gibralter Island, which is near Put-in-Bay in Lake Erie. The event included the latest research and updates on alleviating and managing HABs, and included a live webinar of the presentations.

Presenters were Rick Stumpf, lead scientist and oceanographer with NOAA’s National Centers for Coastal Ocean Science, who announced the forecast, and Margo Schulze-Haugen, deputy director with NOAA’s National Centers for Coastal Ocean Science, who discussed continuing investments to improve forecasts.

Providing an update on the latest information from Heidelberg University’s National Center for Water Quality Research was Director Laura Johnson. And Christopher Winslow, director of Ohio Sea Grant and Stone Laboratory, provided an update on a long list of research projects under way.

Lake Erie blooms consist of cyanobacteria, also called blue-green algae, that are capable of producing the liver toxin microcystin that poses a risk to human and wildlife health, according to an Ohio Sea Grant and Stone Lab news release. Such blooms may result in higher costs for cities and local governments that need to treat drinking water, prevent people from enjoying fishing, swimming, boating and visiting the shoreline, and harm the region’s vital summer tourism economy. The effects vary in location and severity due to winds that may concentrate or dissipate the bloom.

The size of a bloom and its toxicity are different, the release said. For example, toxins in a large bloom may not be as concentrated as in a smaller bloom.

Researchers said this year’s bloom is expected to begin in late July. The lake temperature has remained relatively cool due to the higher-than-average rainfall in the region, so the bloom is not expected to start until the water temperature reaches 65-70 degrees. This contrasts with 2018, when exceptionally warm weather at the beginning of June caused an early start.

Calm winds in July, especially in western Lake Erie, tend to allow the algal toxins to concentrate, making blooms more harmful, the release said. The bloom typically peaks in the western part of the lake in September. Most of the rest of the lake will not be affected.

“This extremely wet spring has shed light on the movement of nutrients from the land into Lake Erie,” said Winslow. “Despite the predicted size of this year’s bloom, portions of the lake will be algae free during the bloom season and the lake will remain a key asset for the state. Ongoing research continues to help us understand bloom movement and toxin production, and remains vital to providing our water treatment facilities with the tools, technology and training they need to keep our drinking water safe.”

NOAA uses satellites to collect information and to refine and improve the models used to develop forecasts.

“This spring brought regular, heavy rainfall to the Maumee River watershed which would normally carry a lot of nutrients into the lake,” said Stumpf. “However, due to the amount of rain this year, farmers were unable to plant their fields which reduced the nutrient concentration. That combined with higher-than-normal lake levels, presents an opportunity to test the accuracy of our models.”

Nutrient load data for forecasts is provided by Heidelberg.