Wetlands Loss Pushed Residential Flood Claim Payments by $10B, Report Shows

Wetland loss across the U.S. has driven up residential flood insurance claim payments by more than $10 billion in the past 40 years, a new study shows.

The study, published in Nature Water, residential flood insurance claim payment amounts increase by an average of 0.01% to 0.03% per hectare (roughly 2.5 acres) of upstream wetland loss. That amounts to a nationwide increase to $10.1 billion, since 1985.

Costs increased the most in the Houston metropolitan area, southeastern Louisiana and coastal Florida.

The study, authored by Environmental Defense Fund researchers, links changes in upstream wetland area to downstream National Flood Insurance Program claims at the sub-watershed level. The analysis focuses on riverine flooding (how the loss of upstream wetlands affects downstream flood damage along rivers and streams).

In the top 10% of sub-watersheds, every one hectare of wetlands provides roughly $24,783 in residential flood risk reduction value.

Roughly 30% of average annual flood losses are insured by the NFIP. Accounting for uninsured or privately insured losses, the total costs of historical wetland loss since 1985 could exceed $33 billion, the study’s authors note.