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Every summer, the same devastating story repeats across America: lakes that families have cherished for generations suddenly turn toxic green. Half a million people in Toledo lose their drinking water when Lake Erie blooms with poison algae. Or, Florida’s red tide costs the state billions in lost tourism. But some of the most damaged bodies of water in America are getting a cleanup. Meet Dr. Mark Heilman, Vice President of Environmental Restoration and Advocacy at SePRO, whose two decades of water restoration work have brought 1.4 million acres of polluted lakes and wetlands across North America back to life. Mark’s team achieved a 42% reduction in harmful phosphorus levels and protected $300 million in annual tourism revenue at Moses Lake, Washington.

When phosphorus from fertilizers and runoff enters our waters, it acts like Miracle-Gro for algae, creating massive blooms that choke aquatic life and produce toxins that cause liver damage, neurological problems, and even death. U.S. Environmental Protection Agency assessments show the number of overly productive lakes with poor water quality is increasing. Harmful algal blooms are becoming more frequent and intense. Perhaps most striking is Heilman’s noting that even benign-seeming weekend lawn care directly contributes to this crisis: a bushel of grass clippings that reach a waterway contains about a tenth of a pound of phosphorus, the same amount found in a box of Miracle-Grow fertilizer. When dumped into a waterway, those clippings can grow up to 50 pounds of algae. Heilman explains that treating a lake is like “performing surgery on an entire ecosystem,” a process that involves a comprehensive assessment of water quality, community engagement, and multi-year management programs. The climate crisis is intensifying these challenges as warming water temperatures favor cyanobacteria growth, while invasive species like hydrilla—what Heilman calls “disturbance specialists”—exploit changing environmental conditions to establish footholds and outcompete native species. Yet he remains optimistic about prevention: “It’s easier to prevent, takes less resources and investment to prevent them than to actually try to resolve them once these problems are in the environment.” You can learn more about SePRO’s restoration work at sepro.com.