Signs posted around the Grand Lake, Ohio read: “Danger: Avoid all contact with the water.” When dangerously high levels of toxins from blue-green algae in Grand Lake, Ohiio were publicized in 2009, many residents and tourists stopped using the 13,000-acre lake in northwest Ohio. Hotel revenue and home values sank for several years as algae bloomed in the state’s largest inland lake.
Greenish water still laps at Grand Lake’s shores, but recent water samples show that the amount of algae-feeding nutrients entering the lake is down significantly. State, federal and private donations covered more than $10 million in projects aimed at improving water quality. More people are boating on the lake again. Grand Lake could now serve as an example for communities with algae problems across the nation, experts say.
Algal blooms are on the rise, from Lake Erie to the Florida Everglades. In August 2019, the Environmental Protection Agency listed algae-related beach closures or health advisories in 23 states, and it said other blooms may not have been reported. In 2010, the EPA found that 20% of 50,000 lakes surveyed had been affected by phosphorous and nitrogen pollution, which feeds algae.e Cleaning up bodies of water choked with toxic algae has proved difficult. The project to repair Grand Lake, once one of the most polluted by algae in the nation, is one of the clearest successes. It shows cleanup is possible, but also expensive and time-consuming.
“It’s not restored yet, but it’s on the road to recovery,” said Stephen Jacquemin, an associate professor of biology at Wright State University-Lake Campus in Celina. Beginning in 2012, wetlands areas were built around the lake, which was hand dug in the 1830s. The thick stands of bulrushes and other plants have reduced phosphorous and nitrogen levels in water entering the wetlands before reaching the lake by as much as 90%, Dr. Jacquemin said. Three wetland areas, which cost a total of about $6 million to build, are constructed as a series of interconnected pools that allow particulates to settle out and plants and microbes to remove nutrients.
The state’s Department of Natural Resources has also dredged the lake bottom to remove nutrient-loaded sediment, and tried to clean up one of Grand Lake’s beaches near St. Marys by building a rock jetty and installing aerators and a curtain to filter water. Recent water tests there showed levels below 6 parts per billion of the toxin microcystin, under Ohio’s threshold of 20 parts per billion for avoiding contact with water.
As Green Algae Forces Beaches to Close, Ohio Lake Offers Hope, WSJ, Sept. 18, 2019