As Nation's Flood Risks Grow, Protecting Wetlands Is More Important Than Ever

Many neighborhoods and communities across the U.S. have seen firsthand the impact of escalating flood risks in recent years. In just the past year, catastrophic flood events occurred in Oklahoma, Texas, South Carolina, Missouri, and Illinois, to name just a few places. Heavy downpours in these states caused widespread flooding, which led to loss of life and billions of dollars in damage to homes, businesses, and infrastructure.

Flood risks have increased as climate change has made heavy rainfall events both heavier and more frequent, greater urbanization has led to more pavement covering ground previously available to absorb rainwater, and expanded development in coastal and inland areas prone to flooding has increased flood vulnerability. Despite these growing risks, we can help guard against the toll of future flood disasters by implementing the Clean Water Rule, which would help protect an essential feature of the landscape that reduces flood risks--wetlands.

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Wetlands, such as marshes, swamps, and wet meadows, are commonly found in inland and coastal floodplains. They provide a variety of important benefits, including water quality improvement, enhancement of groundwater recharge, fish and wildlife habitat, recreation and economic opportunities, and flood protection. Wetlands are a critical tool for reducing flood risks because they can absorb large volumes of water. A single acre of wetlands one foot deep can absorb 330,000 gallons of water--a volume large enough to flood about 13 homes with several feet of water. Research studies have found that wetlands in a watershed can reduce or slow downstream flooding. A study of a small Canadian watershed estimates that the combined effect of all wetlands (approximately 15 percent of the basin area) reduces flood peaks by 10 percent. Conversely, the loss of wetlands has been found to increase flood risk. In fact, studies have found a strong positive correlation between individual wetland permits and flood damages. That is, projects that alter wetlands (particularly in the 100-year floodplain) result in significantly greater flood damage.

Despite the many critical benefits of wetlands, the U.S. has lost roughly half of the wetlands that existed in the late 1780s as these areas were filled in to build cities, drained for farmland, or starved of sediment and left to erode away. As Environment America explains in its Shelter from the Storm report, passage of the federal Clean Water Act in 1972 has helped to reduce wetland loss by requiring permits for filling in these valuable ecosystems. Supreme Court decisions in 2001 and 2006, however, have undermined these protections by creating uncertainty about what types of waters are protected by the law. The Clean Water Rule, finalized by the U.S. Environmental Protection Agency and the U.S. Army Corps last year, would restore protections for wetlands left vulnerable by this ambiguity, ensuring that communities continue to receive the flood protection and numerous other benefits that only wetlands can provide.

About the Authors

Ben Chou

Policy Analyst, Water program

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