What Happens When Wetlands Disappear?

Flooded basements in the spring. Entire downtowns inundated. Millions of pounds of soil washed downstream, destroying farmland, fisheries, and food for wildlife. Whether it's localized flooding or catastrophes such as the midwestern floods of 1993, the entire United States is at risk from increased flooding due to our destruction of wetlands.

Photo: © US Army Corps of Engineers

The U.S. Army Corps of Engineers has studied the causes of flooding and advocates wetlands protection as the most cost efficient way to prevent flooding. For example, Florida and Louisiana were both hit directly by Hurricane Andrew in 1992. Florida suffered ten times the destruction. The difference? Louisiana had retained more of its coastal wetlands.

Small-scale wetlands destruction can also have far-reaching effects. As they disappear, so to do their abilities to recharge groundwater, collect sediment, and trap pollutants. In addition, isolated wetlands often serve as crucial habitat for small populations of rare birds, insects, and amphibians. For example, only a few whooping cranes nest at Gray's Lake National Wildlife Refuge in eastern Idaho. But if irrigation drew down the water table enough to dry up even portions of this wetland, the crane's nesting success could be threatened by increased predator access or other problems associated with the diminished wetland.

Agriculture and urbanization have devastated the wetlands of California's Central Valley. In previous centuries, this huge valley's wetlands supported 40 million waterfowl. Today, it supports only 8 million waterfowl, with simultaneous reductions in recreation, hunting, and fishing associated with this habitat.

Drawing of Caddis Fly

The impact of wetland destruction occurs far beyond what we can see. Aquatic invertebrates (picture to left is a Caddis fly) are primary consumers in many aquatic ecosystems: they consume algae and other organic matter, and subsequently become food for other types of invertebrates and vertebrates throughout the food web. Some species are found only in a few springs or streams; their loss could ripple out far beyond their isolated wetlands.

The loss of small, seemingly insignificant wetlands causes problems no matter where they are. For example, in urban areas, many construction crews ignore or are unaware of seasonal stream channels and ponds. They fill the depression in the ground without considering the cumulative impact of this landscape alteration. But the subsequent home or business owners will have to deal with the flash floods, wet basements, and inundated parking lots. Downstream water quality begins to suffer, too, and affects life from the micro-organism to the megafauna.

So what are we to do? Learn to live with more floods, less water, fewer fish? Maybe not. Next, you'll find out about people protecting and restoring wetlands.

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