Using Historical Records of Land Use to Improve Wetland Mitigation

Successful wetland mitigation is determined by goals and performance standards of a U.S. Army Corp of Engineers approved mitigation plan. This study collected and reviewed historical data for a mitigation site prior to construction to reduce the cost and risk of mitigation failure. Historical records were reviewed to evaluate the hydrology, vegetation, and soils of a drained Carolina bay wetland. Historical data were obtained from courthouse records, aerial photographs, personal interviews, the local Natural Resources Conservation Service, and the National Railroad Historical Society. Photographs and interviews indicated there was open water before drainage, suggesting a potential source of consistent hydrology. Organic soils subside when influenced by land clearance, drainage, and agricultural activities and could result in a water table above the soil surface once hydrology is restored. Aerial photographs show that several drainage systems have existed over the last 90 yr. Soils along the lines of the earlier drainage ditches and a former railroad line still show disturbance to depths of 1 m. These areas of disturbance could affect vegetation establishment. Records of agricultural practices suggest higher nutrient levels than those of undisturbed Carolina bays, indicating that undesired vegetation could compete with desired vegetation. Historical information verified that Juniper Bay is a viable restoration site and identified areas where design change could help improve chances for success. Similar historical reviews with other mitigation sites can help reduce cost and risk through evaluation of hydrology, soils, and vegetation.