Many aspects of this project, including environmental permitting, have required a joint town and seashore effort. The National Park Service owns the 200-acre marsh where the project is located; the town leases the dike from the Massachusetts Department of Environmental Management. The roles and responsibilities of the seashore, town, and Federal Aviation Administration were codified in a memorandum of understanding, which establishes a National Park Service/Town Review Committee to review progress and advise project scientists, natural resource managers, and airport managers.
In 1930 almost half of the original 200-acre salt marsh was diked in an unsuccessful attempt to eliminate mosquitoes. The airport was built on the floodplain shortly thereafter. The dike’s blockage of tidal flow dewatered and freshened the salt marsh, eliminating habitat for native saltmarsh grasses (Spartina spp.), fish, shellfish, and crustaceans. Spartina grasses in this area have been largely replaced by common reed (Phragmites australis). Phragmites has reduced the value of the wetland as habitat for young fish and shellfish, and changed water quality. Meanwhile, interruption of regular tidal flushing and predatory fish access allows mosquitoes to breed in abundance.
Restoring the salt marsh will have many benefits. Restoration will increase nursery habitat for commercially important shellfish, crustaceans, and fish, many of which reduce mosquito populations and are prey for larger animals. Productivity will rise for saltmarsh plants as well. In addition, restoration of regular tidal flow will allow the wetland to again grow upward along with rising sea level. This will provide increased storm surge protection for the airport.
To restore the salt marsh, the dike’s present 2-foot-diameter culvert will be replaced by four 7-foot-wide by 3-foot-high box culverts with adjustable gates. The new culverts will be opened gradually over several years to increase tidal range and encourage salt-tolerant spartina to replace more salt-sensitive phragmites. The phased opening also allows project scientists to monitor and control changes to avoid, for example, a sudden die-off of vegetation. A rapid die-off would create open water and mudflats that would attract feeding birds, a safety hazard for the airport. Low (average 2-foot) earthen berms will be constructed around the airport’s instrument landing system to maintain a stable water table in this sensitive area.
National Park Service, U.S. Geological Survey, and University of Rhode Island scientists have conducted pre-restoration environmental monitoring since 1997, collecting water chemistry, vegetation, fish, and shellfish. These data establish a base from which to track changes with restored tidal flow. All participants in this ambitious effort expect that knowledge gained at Hatches Harbor will be important to other restoration projects in the state and beyond.
charles_farris@nps.gov
Ecologist, Cape Cod National Seashore, Massachusetts
RETURN OF RARE PLANT
Unrecorded at Assateague Island National Seashore (Maryland) for the last 32 years, the threatened sea amaranth was rediscovered on an open beach in summer 1998 by a park wildlife technician. Before the find, the plant species was known to occur only on Long Island and in the Carolinas. An annual, it sprouts only from seed, presumably transported by the ocean, and is considered an indicator of unimpaired natural shoreline processes. Only two plants were found at the park, and both were threatened by Hurricane Bonnie in August as they were beginning to fruit. With great potential to restore the species to the mid-Atlantic, one plant was removed to a greenhouse, where it thrived, producing hundreds of seeds. The other plant was inundated and died.
FATE OF DAMS STILL UNCERTAIN
Congress has appropriated funds ($29.9 million) for the acquisition of the Elwha River dams in and near Olympic National Park (Washington). However, before the dams can be acquired, the Secretary of the Interior must demonstrate that the additional $83.3 million (1995 dollars) required to remove the dams and fully restore the Elwha River ecosystem and fishery will be available within two years of acquisition. No funds have yet been appropriated for dam removal and restoration, although the President’s FY 2000 budget includes $12 million for this purpose.
Back to Chapter 5: Resource Restoration
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by Thomas Kucera
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Partners restore wetland in the Santa Monica Mountains NRA
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Relief funds expedite watershed restoration program
by Darci Short