Loss of Wetlands in Dakotas a Problem For the Entire United States: A Study

Wetlands in eastern North and South Dakota are shrinking at a rapid pace, according to research conducted by Carol Johnston, a South Dakota State University professor.

By comparing wetland maps from the U.S. Fish and Wildlife Service and the U.S. Geological Survey, Johnston of the school’s Natural Resource Management Department was able to identify those areas that, though once wetlands, have since been converted into cropland.

Afterward, she verified her findings using aerial photos.

In doing so, she focused on the Prairie Pothole Region in the eastern Dakotas given that it is where the majority of wetlands and croplands are located as well as serving as a habitat for more than 50 percent of North American migratory waterfowl.

In her article published in Wetlands, the Journal of the Society of Wetland Scientists, Johnston effectively demonstrates a yearly loss of nearly 13,000 acres of wetlands between the 1980s and 2000 - a number that increased to 15,377 within the last decade.

These changes, Johnston warned in a press release, not only affect wildlife but humans as well.

“Wetlands provide many ecosystem services,” she said, including improving the quality of water downstream by trapping sediment and filtering out pollutants such as phosphorus.

“Wetlands are called the kidneys of the landscape,” she said, pointing to their ability to convert nitrate into harmless nitrogen gas. Without these filtering effects, these nitrates can render the water unfit to drink and give rise to algae that, when they decompose, decrease the oxygen available for fish and aquatic organisms.

Nor does it stop there.

Because wetlands’ shallow reservoirs hold excess water, they can also reduce flooding downstream, Johnston explained, citing an instance in which wetlands along the Charles River in Massachusetts were bought and maintained specifically for the purpose of reducing floods in the city of Boston.

Ultimately, Johnston said, a loss of wetland in the Dakotas affects a much larger area.

“Loss of nutrients as a result of wetland drainage can increase the amount of nitrogen going downstream,” she explained. “What we do in South Dakota impacts people all the way down to the Gulf of Mexico.”