CASCADE BROOK SALT MARSH RESTORATION PROJECT

The United States Fish and Wildlife Service contracted Tetra Tech, Inc. (formerly Northern Ecological Associates, Inc.) to conduct pre-construction and post-restoration monitoring within an 88-acre portion of the Cascade Brook salt marsh area located within the Scarborough Marsh Wildlife Management Area, Scarborough, ME, in response to a culvert failure along Old Blue Point Road. The goal of the restoration and monitoring effort was to restore the native marsh surface elevation to allow native salt marsh vegetation to repopulate the marsh; reduce the constriction of tidal flow to the marsh, thereby increasing salinity and reducing freshwater pooling on the marsh surface; and, remove or control the large populations of common reed (Phragmites australis), an invasive plant, from central areas of the marsh that were historically dominated by salt meadow grass (Spartina patens) or other native salt marsh species. Pre-restoration monitoring was conducted in 2002, restoration activities were conducted in 2003, and post-restoration monitoring occurred annually between 2004 and 2008. A combination of qualitative and quantitative assessments was used to monitor changes associated with restoration activities. Results of the five-year post-restoration monitoring effort documented a positive vegetative response in the spoil removal areas, with desirable salt marsh species rapidly repopulating the areas exposed during restoration activities, emerging from the uncovered, intact seed bank. A review of the water quality data collected over the five-year period revealed a high degree of variability both spatially and temporally, but no clear trend of increased salinity. In the common reed control and removal areas, reestablishment of common reed was documented, however the extent has been reduced in comparison to pre-restoration conditions, and it appears that the reestablishment of native species has slowed the regrowth of common reed. Long-term predictions for the site include the continued expansion of common reed in those areas where it has become reestablished, however it appears that native vegetative species will persist within the targeted restoration areas, resulting in an overall increase in diversity and restoration of native salt marsh species at the site.