The long-range management objective for the Scarborough Marsh is to provide suitable habitat for optimum levels of all wildlife species and to provide maximum utilization of the area by sportsmen and other individuals seeking outdoor recreation. The marsh is Maine ’s largest and most renowned salt marsh and is recognized for high biological productivity and diversity. The marsh provides habitat for estuarine and catadromous fish species, and supports state and federally-listed threatened or endangered species.
Restriction of the natural tidal flow by railroads, and public and private roads, historical salt hay production drainage ditches and farm roads had created tidal restrictions and excessive drainage. This had caused loss of natural tidal pools, ecosystem functions and values and had allowed invasive vegetation to alter the marshes, reducing their value as a habitat and as a resource for the marine environment.
Cascade Brook, one of five major tributaries in the Scarborough Marsh system, was the second phase of the restoration project and included 100 acres of salt marsh. An unused water control structure severely limited tidal flushing, and two underwater berms in the channel behind the water control structure also served as tidal constrictions. In a 1996 500-year flood, a culvert on the Old Blue Point Road blew out, and large quantities of spoil material smothered two acres of the marsh surface and filled a tidal creek. In addition, 45 large piles of peat were ripped out of the marsh during the flood, floated downstream, and came to rest on the surface of the marsh. Non-native Phragmites aggressively invaded the newly disturbed areas. Restoration work included: (1) lowering the water control structure to increase tidal flow; (2) partial removal of the underwater berm; (3) removal of 5,000 cubic yards of spoil material on the surface of the marsh and in the tidal creek; (4) removal of peat piles; and (5) Phragmites control. Project completed in 2004. A 5-year monitoring process is ongoing.
The third phase of the restoration project affected approximately 381 acres of the Mill Brook salt marsh. Man-made ditches had excessively drained substantial sections of the Mill Brook marsh, lowering the natural water table and destroying permanent pool habitat that once supported a suite of species (aquatic plants, invertebrates, fish, shorebirds, wading birds, and waterfowl). This area was further troubled by an extensive Phragmites invasion, in part as a result of excessive fresh-water run-off from upland developments. The restoration project was broken down into three segments. Total project included: (1) Creation of one ditch; (2) Creation of 25 plugs in 25 man-made ditches; (3) Treatment/mulch of 18 identified Phragmites patches/colonies; (4) Two breaches in man-made berms; and (5) Maintenance of three man-made ditches. Project completed in 2005. Two more phases of the project are still to be completed.
Libby River – A culvert has long been identified as a tidal restriction, and clearly contributes to an extensive growth of Phragmites upstream of the culvert on the eastern edge of this area of the marsh.
Nonesuch River – Man-made ditches, an old road berm, and an extensive Phragmites invasion are the primary impacts of concern.