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Ten years ago this August, at 2 a.m. on a Saturday, Toledo, Ohio, residents received an alarming notice from local officials: Do not drink the water.

A massive algae bloom in Lake Erie had overwhelmed the city’s water treatment plant and with microcystin, a toxin produced by algae that can damage the human liver and kill birds, pets, and livestock. The state’s governor declared a state of emergency as, for nearly three days, close to half a million people were unable to use their tap water to cook, bathe, or brush their teeth. 

Harmful algae outbreaks were nothing new for Lake Erie. The blooms, fed mainly by phosphorus in farm runoff, routinely cover hundreds of square miles, spoiling summer fun, putting drinking water at risk for millions, and creating a vast oxygen-depleted “dead zone.” But the Toledo crisis was a wakeup call. The following year, Ohio, Michigan, and Ontario pledged to work together toward a 40 percent reduction in the amount of phosphorus entering the lake’s western basin by 2025.

That ambitious goal is now out of reach, experts say. Governments have relied on voluntary programs that pay farmers to stop nutrients from leaving their farms by, for example, not tilling their fields or by applying fertilizer below the soil surface instead of on top. A report early last year found that, to achieve the agreed-to reduction, Michigan and Ohio would need to for those programs by up to $65 million and $250 million, respectively. A decade since Toledo’s shutdown, algae outbreaks remain an annual scourge. 

In the ongoing effort to bring the problem under control, the region’s leaders are increasingly reaching for a primitive but proven tool for capturing and cleaning water before it enters the lake: wetlands. No one believes that swamps and marshes alone can starve the algae blooms, but experts say they are an important part of the solution. “Wetlands are wonderful filtration systems,” says Richard Stumpf, an oceanographer with the National Oceanic and Atmospheric administration who monitors algae outbreaks. And because wetlands around the Great Lakes offer vital habitat where birds can rest during migration or raise their young, restoring them not only improves water quality but also brightens the outlook for vulnerable avian species. “There’s momentum building behind nature-based solutions,” says Kyle Rorah, regional director of public policy for Ducks Unlimited. “There’s a huge opportunity to get serious about taking a chunk out of the problem.”

Electric-green cloaks of toxic algae cover lakes and ponds around the country, fed by nutrient pollution from farms, septic tanks, and other sources. Climate change , creating heavier downpours that flush more phosphorus and nitrogen into waterways and warmer waters that speed the blooms’ growth. It’s a particularly vexing issue for the Great Lakes, where fishing, boating, and other water-based recreation is economically and culturally important. All five of the lakes have seen at least occasional algae issues in recent years, especially in heavily farmed watersheds like Lake Huron’s Saginaw Bay and Green Bay in Lake Michigan. No place has been harder hit than western Lake Erie, whose watershed once hosted a million-acre wetland called the Great Black Swamp. Today the merest shadow of that habitat remains, with nearly all the region’s wetlands having been drained for farming. 

The Great Black Swamp can’t be put back together again, but recent, unprecedented investments in wetland restoration aim to reclaim some of its lost benefits. Last year Michigan Gov. Gretchen Whitmer, a Democrat, signed a spending bill with $10 million for ongoing and planned wetland projects to address algae in Lake Erie and Saginaw Bay, and not long after announced another $2 million per year in ongoing restoration funding. 

Around the same time, Republican Gov. Mike DeWine of Ohio authorized a 2024-2025 budget with $270 million for a water-quality program called H2Ohio, up from $172 million when the program launched in 2019. Wetlands are only one component of the effort, but the investment has been substantial: As of March, H2Ohio had poured more than $200 million into 171 complete or in-progress on close to 16,000 acres, according to the Ohio Department of Natural Resources. “The governor has made it a real priority for us to figure this out and protect this water,” says Mary Mertz, director of the department. “We’re excited to do work especially in such an important bird corridor.” 

Those projects come in a variety of shapes and sizes, from building an acre’s worth of in Toledo to across 586 acres at Ottawa National Wildlife Refuge. They are designed to retain and filter water and not necessarily with birds in mind, but they nonetheless provide beneficial habitat, says Nat Miller, ̽����ѡ’s senior director of conservation for the Great Lakes and Upper Mississippi River. “There’s this artificial bias or juxtaposition that you have to design things only for water quality or only for wildlife,” he says. In separate efforts, has restored nearly 20,000 acres of wetlands, Miller notes, and the results are encouraging. “If you get the wetlands there, birds respond to it almost immediately.”

Still, designing and building wetlands takes time. Progress will come slowly and unfold against a more dispiriting backdrop: From 2009 to 2019, the United States lost 670,000 acres of vegetated wetlands such as marshes and swamps, and the Great Lakes region was among the hardest hit, the U.S. Fish and Wildlife Service . Some developers and farmers, among others, continue to regard wetlands as impediments to progress. Indiana cut protections for wetlands in 2021, then earlier this year. Following a U.S. Supreme Court decision in 2023 that curtailed federal regulation of wetlands, it is weakening its rules. 

On the whole, though, states that depend on the world’s largest source of surface freshwater are embracing wetlands as water-quality infrastructure, says Brian Vigue, freshwater policy director for ̽����ѡ Great Lakes. In Wisconsin, for example, Vigue says many in the Republican-majority legislature until recently viewed wetlands as a nuisance. This year, though, they with $2 million for communities to restore and protect them, after authorizing another $350,000 for a restoration project in the Green Bay watershed led by the Oneida Nation (of which Vigue is a citizen), ̽����ѡ Great Lakes, and other partners. “This is unbelievable that Wisconsin is doing this after the way things were just a few years ago,” he says.

There’s a long way to go to free the Great Lakes of foul, suffocating blankets of toxic algae, and public emergencies like Toledo’s remain a troubling possibility. But annual outbreaks are not some inexorable fact of life that the public must accept—the problem in its current, severe form began only about two decades ago as farming practices changed, Stumpf says. The relationship between the amount of phosphorus in the water and the size of algae outbreaks, he adds, is not linear: “Getting it down some will really knock down the biggest blooms.” And the bigger the role wetlands play in that effort, the more birds will benefit, too.