Kingman Lake is not a true lake, but a 110-acre tidal freshwater impoundment created during the 1920s and 1930s to provide a recreational boating area for District of Columbia residents. The lake is connected to the tidal Anacostia River by two inlets located at the northern and southern ends of Kingman Island, a wooded 94-acre dredge/fill-created island that separates the lake from the river.
Years of sedimentation had turned Kingman Lake, once a tidal marsh, into a mudflat.
Historically, the area emerged as an expansive freshwater tidal marsh, renowned for its migratory sora rail population. As wetlands were dredged and filled, many such migratory birds stopped coming. The open water tidal "lake" gradually filled with sediment until the dominant low tide feature was a mudflat. Because of the lack of suitable substrate elevation, most species of emergent marsh vegetation have not been established over the existing mudflats.
From mudflats to wetlands
With support of section 319 funding, in 2000 the U.S. Army Corps of Engineers, Baltimore District, led the restoration of 42 acres of the freshwater tidal emergent wetland in Kingman Lake. Other key partners included the U.S. National Park Service, the D.C. government, and neighboring Prince George's County in Maryland. The primary goal of the restoration plan is to restore historically significant wetlands, thereby enhancing the habitat diversity and structure of an area currently dominated by unvegetated tidal mudflats.
To re-create vegetated tidal wetland habitats, the morphology of the lake was altered by filling and grading existing lake mudflats with Anacostia River dredge material. Establishing new (higher) substrate levels on Kingman mudflats was key to creating an environment suitable for the growth of emergent wetland macrophytes, which can tolerate only moderate levels of tidal inundation.
Approximately 700,000 emergent wetland plants were planted in the newly elevated and graded mudflat areas. It was soon discovered that goose exclusion fencing would be necessary to prevent the plants from becoming a "free lunch" for the lake's resident Canada goose population. The fencing will allow the plants to gain a foothold during their first crucial growing season.
In concert with the wetland restoration work, Kingman Island is also being restored. The restoration primarily involves the removal of materials that historically have been dumped on the island. A number of low-impact actions are also under consideration, including the removal of invasive exotic plants. Also being considered is the construction of ramps and a floating boat dock for canoes and kayaks, as well as an interpretive nature trail for the recreational enjoyment of District residents. Enhancement of habitat for resident and migrating wildlife is also considered a priority. It might take the form of bird boxes, nesting areas for ospreys and eagles, and bat boxes, as well as artificial deadfalls and snags for species-specific nesting.
The restoration project has succeeded in transforming Kingman Lake back into a marsh.
A prerestoration study will establish a baseline data set of aquatic biota and water quality parameters by collecting monthly water quality data and conducting a multiyear summer seasonal assessment of the benthic macroinvertebrate, fish, plankton, and bird communities living in or using Kingman Lake. After restoration is complete, the study will continue for 5 years to determine the relative impact of the restoration efforts on the water quality and the aquatic community.
Implementing these two significant restoration projects in the main stem of the Anacostia River is important not only for the improvements to wildlife habitat or water quality. The projects also demonstrate the success of large-scale environmental restoration projects involving multiple federal and local government agencies and funding sources.