Moderate harmful algal bloom forecast

PUT-IN-BAY — Scientists are predicting a "moderate" harmful algal bloom in western Lake Erie this summer, similar to 2024 but larger than the 2025 bloom. The bloom this year will have an intensity of 3.5 on a scale of 1-10 with 10 as the worst, equal to the record bloom in 2011, said Rick Stumpf, a National Oceanic and Atmospheric Administration scientist who delivered the forecast. The possible range for this year's bloom is between 3 and 4.5, Stumpf said. Last year's bloom had an intensity of 2.4, Stumpf said. Stump and other scientists delivered the 2026 algal bloom forecast at an annual event hosted by The Ohio State University's Stone Laboratory at Put-in-Bay. The forecast released Thursday was the 14th-annual forecast that's been provided. This year's forecast was delivered to an audience that included local politicians and water quality scientists and was also broadcast via Zoom. Breakdown on the bloom Stumpf said that this year's harmful algal bloom likely will begin in July. It will likely: • Become more intense in August and will continue into September • Be confined to the western basin of Lake Erie • Be a moderate bloom, said Stumpf, who noted that the huge 2011 bloom extended east "way past Cleveland." Discussing the dangers from the bloom, Stumpf said that when boaters and people on shore see a blue-green scum on the surface of the lake, they are looking at a substance that is toxic. When the scum is present, keep your kids and everyone else out of the water and keep dogs out of the water, Stumpf emphasized. Dogs "do die from this," he said. The cyanobacteria that generate harmful algal blooms create a microcystin liver toxin, which can force communities that draw water from Lake Erie to take additional treatment steps. It can also force authorities to close beaches at times. But there should be plenty of areas of the lake that are without scum and which can be safely enjoyed, Stumpf said. Sandusky Bay, which has an annual bloom separate from the main bloom, already has a small bloom, Stumpf said. Stumpf and the other scientists involved in the forecast use a variety of forecasting models, but the data used to determine the size of the event comes from measurements of phosphorus in the water of the Maumee River, which largely drives how big each year's harmful algal bloom is likely to be. Nate Manning, a scientist at Heidelberg University's National Center for Water Quality Research, explained that while the Maumee provides 5% to 10% of the water in Lake Erie, it provides about half of the phosphorus that drives algal bloom growth. Much of the phosphorus this year came from a big storm in April. Ohio also had a huge rainstorm in May that dropped a lot of water over much of the state, but fortunately, little rain fell in the Maumee basin, so it didn't have much effect on this year's bloom, Stumpf said. Manning said Heidelberg University has water monitoring data that dates back to 1975. He explained that while phosphorus affects the size of the bloom, nitrogen levels affect how toxic the bloom will be. Blooms caused problems historically An algal bloom in 2014 temporarily poisoned water supplies in Toledo, forcing residents to rely on bottled water for a few days and heightening awareness of Lake Erie's algal bloom problems. A reporter covering the forecast asked Stumpf if higher temperatures from global warming will cause algal blooms to become larger. "No," Stumpf said. He said warmer weather can cause the algal bloom to begin earlier, and that's why last year's bloom started early. But he said the size of blooms is determined by the amount of phosphorus, not water temperatures. The relatively small blooms of recent years appear to show that Gov. Mike DeWine's H2Ohio program is having a positive effect, although Manning cautioned that phosphorus levels have still not dropped below the target the state has set. DeWine's program includes paying farmers to adopt conservation practices to reduce phosphorus runoff from their land and rebuilding wetlands, which serve as natural filters to reduce the amount of phosphorus flowing into Lake Erie. DeWine is in his final year as governor and Ohio will elect a new governor this fall, who could make changes in the ongoing water quality program. What's the impact of wetlands? The Register asked what effect wetland restoration is having on dealing with harmful algal blooms. Manning replied that wetlands do help, although much depends on the design of the wetlands. Some designs work better for controlling blooms than others, he said. Eric Saas, H2Ohio wetlands program manager for the Ohio Department of Natural Resources, added that wetlands restoration in Ohio has been carried out on an historic scale. A new report on wetlands monitoring in 2025 will be out soon, likely in August, and it will include "a lot of good news," Saas said.