National Wetland Inventory (NWI) Maps
Why are Wetlands Important?
Wetlands are home to thousands of wetland plants and animals, such as beaver, alligator, crayfish, and insects. Ducks depend on wetlands to nest, feed, rest, and raise their young. Many fish live, feed and spawn in wetlands. Frogs and salamanders depend on wetlands for all or most of their life. Many plants live nowhere else but in wetlands. A recent analysis suggests that 50 percent of North American birds depend on wetlands. An estimated 46 percent of U.S. endangered and threatened species need wetlands to live.
Wetlands soils absorb water from precipitation, plants slow the water’s flow, low wetland areas hold water, then release the water slowly into streams. Natural wetlands do filter out chemicals and fertilizer that people have put on their farms, lawns or discharged from their businesses.
Wetlands provide food such as fish, rice, cranberries, and clams. Many people make a living harvesting natural products from wetlands.
You can birdwatch, view other wildlife, boat, walk, or take photographs in wetlands. Many people fish or hunt in wetlands. And, of course, wetlands provide openspace for beauty and can enhance property values.
How many wetlands do we have?
We estimate there are 105.5 million acres of wetlands, or 5 percent of the land area, in the lower 48 states. Many of these wetlands are in the southeastern United States. Alaska is estimated to be about 45 percent wetland, and Hawaii is 1 percent wetland. From a high of 458,000 acres lost per year between the 1950’s to the 1970’s, today the U.S. is now still losing 58,500 acres a year. Crucial small, isolated, or temporary wetlands are often lost first.
Many of our remaining wetlands have been degraded and cannot help reduce floods or serve as habitat for wildlife or are degraded because of fertilizer, hazardous chemicals, or the introduction of invasive species.
What happens when wetlands are lost?
When wetlands are degraded or lost, more animals and plants that rely on wetlands are harmed or jeopardized. Birds, fish, frogs, and other wetland creatures are declining. For amphibians, 40 percent of species are imperiled or vulnerable. It is estimated that 37 percent of all U.S. fish species are imperiled. Also, there are increases in flood or drought damage. Water quality gets bad, affecting wildlife, drinking water, water related recreation, and property values.
How does mapping wetlands help address problems facing wetlands?
To protect wetlands, you must know what kinds of wetlands you have, where they are, and what is happening to them, ie, their currrent status and the trends of losses or gains. Wetlands are mapped to show their current status, and updated or sampled to show their trends of losses or gains. Once wetlands are mapped, many types of wetland assessment can be performed. Wetland assessment is used for many activities: monitoring wetland health, making permit decisions, targeting voluntary wetland restoration activities, maintaining biodiversity, restoring species, measuring mitigation success, undertaking watershed management, developing wetland classifications, protecting public water supplies, implementing local land use plans and so on.