When a Louisiana home floods, the insurance check that arrives often masks a deeper loss—one written into the landscape decades earlier. A new study published in Nature Water reveals that the disappearance of America's wetlands since 1985 has cost households $10.1 billion in flood insurance claims alone, with the true price tag likely exceeding $33 billion when uninsured losses are included. The research, led by Environmental Defense Fund economists Jesse Gourevitch and Adam Gold alongside Helena Garcia, a Ph.D. candidate at the University of North Carolina at Chapel Hill, connects upstream wetland loss to downstream flood damage in ways previous studies could not.
Wetlands are nature's shock absorbers. They soak up water like sponges during heavy rains, slowing runoff before it reaches communities downstream. Yet their value has been systematically overlooked in policy and land-use decisions, allowing these ecosystems to vanish quietly while their consequences ripple outward in rising insurance claims and devastated neighborhoods. The researchers analyzed nearly four decades of data, tracking how changes in upstream wetland area between 1985 and 2023 affected residential flood insurance claims through the National Flood Insurance Program at the sub-watershed level nationwide, accounting for local rainfall and underlying flood risk.
The numbers are stark. For every hectare—roughly 2.5 acres—of upstream wetland lost, residential flood insurance claim payments increase by an average of 0.01% to 0.03%. Cumulatively, this translates to a 9.0% increase in total claims since 1985. The damage concentrates in predictable places: the Houston metropolitan area, southeastern Louisiana, and coastal Florida all experienced the sharpest cost increases. These are the regions that have lost the most wetlands and face the most frequent flooding.
But the study also found surprising value in what remains. In the top ten percent of sub-watersheds, every single hectare of existing wetland provides at least $24,783 in residential flood risk reduction value. In the most critical one percent, individual hectares are worth over $301,000 in avoided flood damage. These figures suggest that wetland conservation isn't just environmentally sound—it's economically rational in regions where protection costs are lower than the benefits of avoided flood losses.
In 16% of sub-watersheds, particularly in flood-ravaged areas of Kentucky, West Virginia, and Pennsylvania, the economic case for wetland protection is overwhelming: the benefits outweigh conservation costs. Yet across much of the country, inaction continues. The research also documents an injustice embedded in these patterns. Historical wetland loss has disproportionately increased flood damage in lower-income communities and communities with higher shares of non-white residents, deepening existing inequalities in disaster exposure and recovery capacity.
"Wetlands act like natural sponges during heavy rain, storing floodwater and slowing runoff before it moves downstream," Gold explains. "Yet wetlands continue to disappear, in part because the value of the services they provide is often overlooked."
The study's implications reach far beyond academia. Federal agencies can use these findings to improve benefit-cost analyses for wetland regulation and infrastructure spending. State lawmakers can anchor wetland protection policies in concrete economic data. Conservation organizations can make smarter investment decisions about easements and acquisitions. Flood insurers can better reflect actual risk reduction in pricing. Most urgently, the research provides evidence that will be critical as the Trump Administration proposes a narrower federal definition of "Waters of the United States"—one that could leave up to 91% of non-tidal wetlands unprotected. The choice facing policymakers is clear: invest in protecting the wetlands that remain, or continue paying billions in insurance claims for preventable floods.