Stony Brook Salt Marsh Restoration, Brewster, Massachusetts
The Stony Brook watershed contains some of Brewster’s most important and valuable natural and historic resources. These include one of the Commonwealth’s most popular herring runs at Stony Brook, 386 acres of herring spawning area in five headwater ponds, salt marsh, wetlands, rare species, over 900 acres of protected open space, the historic Stony Brook mill, and scenic vistas.
Route 6A, a state highway, divides the Paines Creek-Stony Brook salt marsh into two separate wetlands: a salt marsh on the north side and a brackish marsh and shrub swamp on the south side. Two tidal culverts run under Route 6A. Stony Brook runs under Route 6A through an undersized culvert known as tidal restriction BR-6 in the Cape Cod Atlas of Tidally Restricted Salt Marshes (Cape Cod Commission, 2001). A secondary channel passes through a second tidal culvert known as BR-5. Both culverts are too small to allow Stony Brook to flow freely under Route 6A, and are blocking and slowing the passage of salt water into the southern marsh.
Figure 1. Route 6A, Stony Brook, and tidal culverts BR-5 (red dot on left) and BR-6 (red dot on right), Brewster. Town of Brewster, 2006.
The salt marsh south of Route 6A along Stony Brook has been greatly altered and degraded by human activities, including diking, berming, channelization, and road-building. The two undersized culverts under Route 6A are too small to allow natural tidal flows to occur, and are causing a tidal restriction that blocks and slows the flow of salt water into the southern marsh. The result is that much of the former salt marsh that existed prior to these activities has been replaced by freshwater wetlands, allowing woody shrubs and invasive non-native Common Reed (Phragmites australis) to spread (see photo on first page). This has caused the southern marsh to change from a salt marsh to a brackish to fresh marsh, encouraged the spread of woody plants that prefer fresh water, and encouraged the spread of Phragmites. Healthy salt marsh provides key economic and ecological benefits such as flood control, protection against storm surges, pollutant removal, fish and wildlife habitat, and scenic vistas that benefit the Cape’s coastal economy. Restoration of salt marsh therefore will protect and enhance the Cape’s ecology, economy and residents.
The undersized culverts also hinder fish passage due to their small diameter. Restoration of natural tidal flow would enable herring to migrate more easily under the highway to their spawning areas in Lower Mill Pond, Upper Mill Pond, Walkers Pond, Canoe Pond and Slough Pond. River herring, an important food source for many other fish and wildlife species, have declined to dangerously low numbers in recent years, so restoration is all the more urgent. Other fish will benefit from the naturalized stream flow.
Figure 2. Tidal culvert BR-6, north side of Route 6A. Photo by J. Muramoto, 2006.
The Town of Brewster is restoring approximately 20 acres of salt marsh and improving the herring run south of Route 6A by restoring tidal flow to the wetland south of Route 6A. The Stony Brook restoration project will replace the undersized 3-foot culvert at BR-6 with two 9-foot culverts that will restore tidal flow to approximately 20 acres of brackish wetlands, thereby restoring salt marsh habitat and enabling river herring to migrate more easily to their spawning areas in the headwater ponds. Restoration of tidal flow is also expected to reduce the area of invasive Common Reed (Phragmites australis) which has displaced much of the native vegetation in the valley.
From 2007 through early 2009, the Town conducted the first phase of the project: a feasibility study to identify the best restoration option. This study involved the use of numerical modeling to see how different restoration scenarios involving different sizes and combinations of culverts might affect tidal flow and the area of restored salt marsh. A total of six different restoration scenarios were evaluated. The best restoration option involves enlarging the eastern BR-6 culvert to 18 feet in diameter. In practice, this would likely translate into two 9-foot-diameter box culverts.
The feasibility study was conducted with a $48,600 grant from the Gulf of Maine Council and NOAA Habitat Restoration Center, with non-federal matching funds and services amounting to nearly $63,000 from the Massachusetts CZM Wetlands Restoration Program, Association to Preserve Cape Cod, Massachusetts Bays Program Cape Cod Region, Corporate Wetlands Restoration Program, private foundation, and many others.
The Town is now in the second phase of the project, involving development of engineering plans, permitting, construction and monitoring. Since work will be done within the footprint of Route 6A, approvals from the Massachusetts Highway Department (MassHighway) will be needed, and the Town will work with MassHighways on developing the final engineering plans for the culvert and road reconstruction. The Town, assisted by its project partners (Wetlands Restoration Program, Association to Preserve Cape Cod / Mass Bays Program, others) received $1.34 million through a NOAA Coastal and Marine Habitat Restoration Grant issued under the 2009 American Recovery and Reinvestment Act (aka federal stimulus funding or ARRA). The total cost of the project is estimated at $1.5 million, and all work, including construction, will be completed within 18 months.
This restoration project will not only result in ecological restoration but will also help to revitalize the regional economy by immediately providing and supporting jobs in diverse sectors including: public works, road and culvert construction, engineering and surveying, environmental consulting, and non-profit organizations.
Project partners include many organizations, agencies and groups:
1) Brewster Department of Natural Resources
2) Brewster Alewife Committee;
3) Brewster Department of Public Works (DPW);
4) Association to Preserve Cape Cod (APCC);
5) Massachusetts Bays Program, Cape Cod Region;
6) Massachusetts Wetlands Restoration Program (WRP);
7) NOAA Restoration Center, National Marine Fisheries Service;
8) Massachusetts Division of Marine Fisheries;
9) Cape Cod Museum of Natural History (landowner);
10) Corporate Wetlands Restoration Program (CWRP);
11) Stony Brook Volunteer Herring Monitors;
12) Massachusetts Riverways Program;
13) Brewster Conservation Trust;
14) Compact of Cape Cod Conservation Trusts;
15) U.S. Fish & Wildlife Service; and
For more information, contact:
Mr. Chris Miller, Project Manager, Director, Department of Natural Resources
Brewster Town Hall, 2198 Main Street, Brewster, MA 02631
Phone: (508) 896-4546
Mr. Jeremy Bell, Assistant Project Manager, Wetlands Restoration Program
Massachusetts Office of Coastal Zone Management, 251 Causeway Street, Suite 800, Boston, MA 02114
Phone: (617) 626-1264
Jo Ann Muramoto, Ph.D., Assistant Project Manager, Massachusetts Bays Program Regional Coordinator for Cape Cod
Association to Preserve Cape Cod, 3198 Main Street, P.O. Box 398, Barnstable, MA 02631
Phone: (508) 362-4226