Mattawoman Creek IBA encompasses 6,138 ha in Prince George?s and Charles Counties and extends from the town of Mattawoman 34 km downstream to Indian Head where Mattawoman Creek widens considerably before entering the Potomac River. The site includes the forested lands of numerous unnamed tributaries which feed into Mattawoman Creek. The boundary of this IBA is based on green infrastructure hubs from Maryland?s Green Infrastructure Assessment. The major habitat types present are floodplain and upland oak-hickory forest, accounting for about 82% of the area and numerous woody wetlands representing about 6% of the area. There are also a few scattered patches of loblolly-shortleaf-pine forest throughout the site and tidal wetlands along the mouth of Mattawoman Creek. Approximately 1,857 ha of the IBA are owned and managed by the Maryland DNR as the Mattawoman Natural Environment Area and Myrtle Grove Wildlife Management Area. Most of the remaining lands within the IBA are privately owned with only a few small parcels owned by either county.
A local naturalist and founding member of the Southern Maryland Audubon Society, George B. Wilmot was instrumental in winning protection of parts of this IBA.
The floodplain forests which drain into Mattawoman Creek support one of the most diverse assemblages of Forest Interior Dwelling Species (FIDS) in Maryland?s Coastal Plain, with 20 out of 24 potentially occurring species regularly breeding in this IBA. Not only do these rich oak-hickory forests provide critical habitat for a highly diverse FIDS assemblage, but also this site supports significant populations of three bird species on the Audubon/American Bird Conservancy Watchlist (category Yellow): Prothonotary Warbler, Kentucky Warbler, and Wood Thrush.
The main threat to this IBA is from a proposed road project (Cross County Connector) that would cross Mattawoman Creek, bisecting the site near the town of Bryans Road. Due to this threat, American Rivers has ranked Mattawoman Creek 4th on its list of America?s Most Endangered Rivers 2009 listing (full report available from American Rivers at: http://www.americanrivers.org/assets/pdfs/mer-2009/mattawoman-creek.pdf ).
The Cross County Connector would link Charles County?s economic hub of Waldorf to the small town of Bryans Road. Direct impacts to the IBA would result from the road?s presence and the construction process and would likely include reduction in creek water quality due to pollution and increased sediment load, forest habitat loss and fragmentation, increased disturbance and the unwitting introduction of invasive plants. Perhaps more severe would be indirect impacts caused by future development encouraged by the new road and by Charles County?s inclusion of much of the creek watershed in the county?s main development district. Such development would likely cause the same impacts listed above but extend them to a larger proportion of the site. These impacts would result in a decrease in the amount of forest interior habitat and reduce the quality of floodplain forests and woody wetlands, which are vital to at-risk species (i.e. Prothonotary Warbler), and the Forest Interior-Dwelling Species (FIDS) assemblage of breeding birds.