Agricultural development and population growth near rivers and in coastal regions have increased nitrogen inputs to water systems, resulting in potable water quality degradation and increased algal bloom occurrences. Wetland restoration and expansion is a solution advocated by researchers from the University of Waterloo. Canada, and the University of Illinois.

Wetlands in the U.S. currently remove about 860 kilotons of nitrogen from riverine and other water systems annually. Analysis of National Wetland Inventory data from the U.S. Fish and Wildlife Service and 5 km grid-Researchers analyzed data on wetland locations and nitrogen loads from fertilizer on farm fields throughout the U.S. Source: Dave Hoefler via UnsplashResearchers analyzed data on wetland locations and nitrogen loads from fertilizer on farm fields throughout the U.S. Source: Dave Hoefler via Unsplashscale estimates of nitrogen inputs and outputs indicates that this removal is limited by a spatial disconnect between high-density wetland areas and nitrogen hotspots. Model simulations suggest that a spatially targeted increase in U.S. wetland area by 10%, or 5.1 million hectares, would double wetland nitrogen removal. This increase would provide an estimated 54% reduction in nitrogen loading in nitrate-affected watersheds such as the Mississippi River Basin.

The costs for a wetlands restoration and expansion program would exceed $3 billion annually, double that of similar efforts implemented on non-agricultural, undeveloped land, but would provide approximately 40 times more nitrogen removal. Water quality improvements and other types of ecosystem services such as flood control and fish and wildlife habitat should be considered when formulating policy regarding wetland restoration and protection.

To contact the author of this article, email shimmelstein@globalspec.com