Federal Aviation Administration safety standards require the Metropolitan Washington Airports Authority to extend the runway at National Airport. However, the effect will adversely impact the Potomac River watershed, so the MWAA is offering $2.5 million to the U.S. National Park Service to improve the Potomac river watershed in the Dyke Marsh area south of the airport. The timing, if the NPS accepts the proposal, will enable the park service to complete phase one of the Dyke Marsh restoration plan: to restore a breakwater in the southern end of the marsh.

The public comment period for the U.S. National Park Service’s Environmental Impact Assessment and related restoration plan for Dyke Marsh ended April 25. The next step is for the NPS to review the public comments and prepare a final restoration plan. At the same time the FAA’s required National Airport runway extension (impacting 1.94 acres) to fulfill airport safety requirements means that the airport mitigation funding required to complete phase one for Dyke Marsh restoration can be realized. The first step of the restoration in the proposed NPS plan is the restoration of the breakwater promontory — a wave break In the location of the former promontory in the southern end of the marsh.

Dredging that took place between 1940 and 1972 which covered 270 acres of the freshwater tidal marsh caused the destabilization and removal of the breakwater promontory. The resulting erosion means the marsh is now disappearing at the estimated rate of 1.5 to 2 acres per year on average. Left without any intervention to halt the degradation, Dyke Marsh will disappear in 30-40 years.

The Friends of Dyke Marsh, the Mount Vernon Council of Citizens’ Associations, the Virginia Nature Conservancy, and the Potomac River Conservancy all support the Airport Authority’s proposed dedicated mitigation funding for the Dyke Marsh restoration. Under the proposed airport authority agreement the U.S. National Park Service must execute a contract by Dec. 31, 2015, and complete the construction by Dec. 31, 2016.