Barrier Beach Preservation and Restoration Plan
Dukes County and the Friends of Sengekontacket (established 1988) formed the Barrier Beach Task Force (BBTF) to examine the state of the Joseph A. Sylvia State Beach, Sengekontacket and Trapp’s Ponds, and to develop long-term plans for monitoring and maintaining these fragile and precious resources. Without the barrier beach, these coastal ponds would cease to exist. As sea level rises landward coastal properties could be greatly impacted. The BBTF works with all levels of government to balance recreation, habitat of rare nesting shore birds, and erosion control. We help identify how state grant monies as well as private donations allocated for the beach should be spent.
In 2008, the Woods Hole Group was hired to develop a Beach Management Plan – Sylvia State Beach, 2008 that addresses the important aspects of managing the barrier beach in a way that balances the concerns of all. The goals of the Beach Management Plan are to preserve and enhance the natural and recreational functions of Sylvia State Beach and to guide future coastal zone management decisions by balancing the needs of all stakeholders. The recommended management activities include:
1) Beach management activities (permits, storm response),
2) Monitoring (existing conditions survey, shorebird survey),
3) Maintenance (parking lanes, fence repair),
4) Restoration (dune restoration, sand nourishment, revegetation)
5) Education outreach (signage, parking lanes, dog regulation)
Critical Restoration Needed
After Hurricane Sandy in November 2012, we increased our efforts to monitor the beach erosion with periodic beach profiles, photographic surveys and GPS surveys input into the Martha’s Vineyard Commission (MVC) GIS database. This information was utilized to develop a proposal to FEMA in February 2013, to help restore areas of major erosion to the beach and the dunes. Unfortunately, after initial positive indications, we have not received support from FEMA. Each year since Hurricane Sandy, we have had further erosion from major winter storms, and are faced with the imminent loss of the dunes in the Oak Bluffs area.
During Hurricane Sandy in November 2012, one of only two inlets to Sengekontacket Pond, at the Little Bridge in Oak Bluffs, was closed due to shoaling and significant erosion and overwash occurred to the dunes of State Beach near Oak Bluffs. The overwash closed Beach Road and damaged portions of the adjoining bike path. Emergency dredging partially opened the inlet and the dredge spoils (~1000 cu yds) were used to provide limited replenishment of the nearby State Beach most affected by the storm. This was the last sand replenishment on the beach.
Early Restoration Projects
Since 1997 there have been 12 replenishments on State Beach, totaling some 190,000 cu yds of sand. The most extensive restoration project in recent times was in 1999, when the State of Massachusetts spent $444,400 in dredging, installing 600 feet of sand fencing, spreading 77,000 cubic yards of sand replenishment and revegetation with beach grass and other plants to totally rebuild the dunes in the Oak Bluffs area of State Beach. This original sand fencing was instrumental in developing the height and breadth of the dunes.
However, the sand fencing was not continued and recent storms have severely damaged the dunes again. During the winter of 2014/15, several sections of the original sand fence posts (some 30 posts) were uncovered by a further 15 feet of erosion to the dune. In several areas the remaining dunes are only 10-15 feet wide. The beach is so close to the road that visitors are stepping over the dunes and continually damaging any remaining or replaced beach grass.
2015 Restoration Project
For 2015/2016, we are proposing a plan, with the help of the Woods Hole Oceanographic Institute Sea Grant Program, to restore critical areas of the dunes. The proposed areas and design of the sand fencing and beach grass replenishment are described in the Technical Assistance on Coastal Processes, State Beach, Dukes County MA - 07/07/2015. No water birds have nested in the area of proposed sand fencing since 2009.
Beach nourishment, sand fencing, and planting dune vegetation are shoreline stabilization techniques that are loses to natural methods of dune recovery. Sandfencing (aka slat fence) used for erosion control might be appropriate for this site. Sand fencing installed with small posts, has 50% porosity which slows down the wind causing sand to accumulate near the fence. It does not survive long when exposed to waves but, if installed landward of the reach of high tide, has relatively low potential negative impacts. After sand has accumulated, by way of the sand fence, the area can be planted and stabilized more naturally with roots from the vegetation. The sand fence is relatively quick way to: build up sand for planting, stabilize the plants during the initial growing season, and prevent additional erosion from foot traffic.
Biomimicry is also an experimental way to build dune height. Biomimicry works best in high elevations (so as not to be washed away) with no existing vegetation (otherwise the beachgrass would accumulate sand as well or better than the biomimicry sticks). Additionally, the method will require relatively frequent monitoring and adjustment in order to make sure the sticks have not been buried or washed away. Experimental areas are planned to determine if the method is effective. They could be expanded or reduced in the future depending on the results from the first few seasons. They have been placed in areas with the greatest chance for success, other areas (such as where the slat sand fence is proposed) would not be appropriate due to low elevation and high foot traffic.
The most effective time to install this type of fencing is in Fall (preferably November placement to be effective during the windier winter season) and planted in Spring (Mid to late March is optimal for beach grass) to stabilize the accumulated sand. American Beachgrass, highly successful on fronting dunes, has been shown to be able to grow through at least a foot or two of sand burial and survive saltwater inundation. Monocultures are not encouraged. The beachgrass could be supplemented with a variety of other grasses and shrubs well adapted to dune protection, for example: Beach Pea (Lathyrus japonicus), Seaside Goldenrod (Solidago sempervirens), Beach Plum (Prunus maritima), Bearberry (Arctostaphylos uva-ursi), etc.
What was discussed at the site visits and presented in documents is not going to be finished in one season. Fencing may need to be adjusted depending on how much accumulation occurs. High accumulation might mean additional fencing to build the dune higher, while low accumulation might mean moving the fencing closer to the dunes, with a longer timeframe for stabilization. However after several years there should be a beach access that is not only going to be more resilient to storms but also allow a greater area of dune function.
Beach grass. For many years FOS has had almost yearly beach grass re-vegetation projects. In 2013, over 8000 sq ft of beach grass was planted on the dune areas over washed during Hurricane Sandy. This has come back very well. Each year since, FOS has continued to replant damaged areas around the pathways and fencing. More extensive re-vegetation will be required during the dune restoration.
Pathway Fencing. FOS continues to maintain and repair the pathways and pathway fencing each. In 2014, we had a major upgrade of a dozen fences to widen entryways and extend fencing to block visitor created footpaths around the entryways.
Entryway numbers were updated in 2014 and are being used by EMS and law enforcement, as well as visitors to identify beach locations.
Signs. FOS has created a comprehensive list of signage in the public beach areas for information regarding the beaches and to increase public safety. FOS maintains the dog signs, numbers, beach rules and shellfish permit access signs. We have also added boat launch signs.
In 2015, we are working to refurbish the large “What is a Barrier Beach” sign at the Little Bridge parking lot.