Lake Erie algal bloom more severe than expected

SANDUSKY — It's back to the drawing board for scientists trying to come up with an accurate forecasting model for the annual harmful algal bloom in western Lake Erie. For the second year in a row, the annual forecast announced at Stone Laboratory at Put-in-Bay underestimated the severity of the bloom. This year's forecast, issued at the end of June, predicted a bloom that would have a severity of 3.5 on a scale of 1 to 10 with a possible range of 2 to 4. An update on Aug. 3 had revised the forecast to a range of 4 to 4.5. Instead, this year's bloom had a severity of 6.8. Last year's forecast had predicted a severity of 3 with a possible range between 2.5 and 5. Instead, it turned out to be a 6. Richard Stumpf, an oceanographer for the National Oceanic and Atmospheric Administration, created an email bulletin from the agency that tracks the bloom and he also participates every year in the Stone Laboratory bloom forecast. He told the Register on Thursday that working on the forecasting model is a work in progress, as scientists try to accurately account for the amount of phosphorus from fertilizer and other sources that apparently feed the blooms. "Last year was a smaller error. But both reflect a nutrient dynamic question. There is a bit more phosphorus in these two years than the models are generally accounting for," Stumpf said. "This could be a shift in rainfall with more discharge in June and July. Phosphorus entering the lake at that time might be completely used. In most past years, the wet/high flow months were March to May, and not all of that is necessarily used. The models need to adapt," Stumpf said. "There are a few other factors, but that starts getting weedy. There is an argument that there is a legacy phosphorus reservoir in the sediments but that hasn't held up in 2016, 2018, low flow years with small blooms," he wrote. The final administration email bulletin on the bloom, which announced the results of the forecast, remarked that while this year's bloom was more severe than last year's, it covered a smaller area. The strength of the bloom is referred to as a "severity index," or SI. "The 2022 bloom was less extensive than in 2021 but was more concentrated, causing the 2022 bloom to be more severe," the bulletin says. This year's bloom also lasted for an unusually long time, well into the fall, compared with previous blooms, the bulletin says. "Discrepancies between the forecasts and the final bloom severity suggest the current models are missing a component of bloom dynamics," the final bulletin says. "We will continue our assessment of the models in order to make improvements to the forecast and severity metrics." Ohio Gov. Mike DeWine's administration has been attempting to reduce the amount of nutrients, such as phosphorus, that are carried into the lake by streams such as the Maumee River and Sandusky River. On Monday, three members of DeWine's cabinet offered updates on the efforts and said they will seek to continue and expand them. Mary Mertz, director of the Ohio Department of Natural Resources, said the state will continue to build and restore more wetlands, which act as natural filters for water flowing into the lake. Dorothy Pelanda, director of the Ohio Department of Agriculture, said the department will seek to persuade more farmers to join efforts to reduce fertilizer runoff. And Laurie Stevenson, director of the Ohio EPA, said the agency will continue to fund efforts to fix septic tank systems. The Erie County Health Department has been receiving money for years from the program.