North Grand River wetland and Stream mitigation Bank
Carroll County, Missouri
Swallowtail has restored a 145-acre northern Missouri farm property to a wetland and stream mitigation bank. Surrounded by rural properties, the wetlands and riparian buffers on this site will help to improve water quality by removing agricultural pollutants. Additionally, a significant amount of wildlife habitat was created or enhanced as a result of this project.
This site previously consisted of rolling upland pastures and low-lying floodplain row crop fields. The agricultural conversion of the site resulted in the straightening and relocation of the streams and the clearing of virtually all of the floodplain trees not immediately adjacent to a waterway. The resulting decrease in flooding allowed the floodplains to be converted to row crop production and the prairies were altered to be cool-season cattle pastures. These activities decreased the quantity and quality of in-stream, riparian, and upland habitat on the site. In addition, agricultural conversion and on-going crop production impaired water quality by reducing floodplain connectivity and wetland acreage while increasing sediment and nutrient inputs to the streams.
In order to address these historic impairments, Swallowtail has made many ecological improvements to the property. These included restoring more than 52 acres of riparian buffer, establishing 21 acres of herbaceous wetlands, and enhancing a 2.6-acre forested wetland. Additionally, more than 67 acres of buffers were established in the rolling hills which surround and protect the wetlands established in the low-lying fields and in depressions within the site’s hillside drainages.
The floodplain wetlands were constructed with a patchwork of microtopography as well as deeper marsh swales. Most of the areas with microtopography have been planted with more than 30 species of appropriate native woody species characteristic of floodplain wetland forests as well as a diverse mixture of wetland grasses and forbs. The marsh swales follow the natural contours of the land, including aspects of the original pre-channelization stream alignment. These areas have been planted with a mixture of shrub swamp and herbaceous wetland species to create habitat diversity. Construction was completed in 2008.