Location

Walker Farm in Barrington, RI is part of the Hundred Acre Cove estuary (identified in the U.S. Fish and Wildlife Service’s North American Waterfowl Management Plan) in upper Narragansett Bay.  The marsh lies to the east of Route 114, the Wampanoag Trail.  This 16 acre marsh includes salt marsh meadow, open water, mudflats, brackish marsh and Phragmites australis.  Today, the majority of the Walker Farm salt marsh is contained within the Osamequin Nature Sanctuary, owned by the Town of Barrington.  The remaining section of the marsh is adjacent to the Town of Barrington’s leaf composting area and community gardens.  The southern tidal restriction is privately owned by an abutting landowner.


Site History

Historically, Walker Farm was used for grazing livestock. Local historic accounts mention the use of salt marshes for grazing in Hundred Acre Cove from as early as 1652.  Dams were built in the early 1900s to block tidal flows and to facilitate the use of pastures.  Dirt roads were built across the marsh to allow access to the farm.  The marsh and adjacent lands across Route 114 were active pig farms until the town bought the land in 1968.  Mosquito ditches were dug throughout the northern portion of the marsh sometime in the mid 1900s.

Impacts to the Salt Marsh: Salt water flow into the marsh is inhibited by five tidal restrictions (identified by arrows in the aerial photo).  The southern inlet restriction is a permanent culverted dam structure that restricts tidal flow.  This culvert allows tidal flow into a small portion of the marsh between the dam and the Walker Farm entrance road off Route 114. Saltwater cord grass, Spartina alterniflora, is the dominant plant in this section of the marsh.  The next tidal restriction to the north is the entrance road off of Route 114 to the community gardens, boat ramp, and composting facility.  The small culvert under the road allows minimum tidal flow into the interior marsh.  Two overgrown farm roads, located north of the Walker Farm access road, cut across the marsh and prevent further tidal inundation into the interior marsh.  At the northern end of the marsh, a flap-gated historic earthen dam was built approximately 60 years ago to allow agricultural use of the marsh. Sometime between 1965 and 1970, the Town of Barrington, made this original dam permanent to establish waterfowl habitat.  This dam flooded the salt marsh and created a brackish pond that only receives tidal flow during extreme high tides and storms.  The dam also impounds freshwater from a tributary that discharges into the northeast corner of the pond, running under Route 114.


Restoration Planning

In 1996, Walker Farm marsh was initially assessed through Save The Bay’s evaluation of the ecological integrity of Narragansett Bay salt marshes.  Trained volunteers from the Town of Barrington assessed the major impacts to Walker Farm marsh.  In 1999, the Rhode Island Coastal Habitat Restoration Team identified Walker Farm marsh as one of 70 candidates for ecological restoration in Rhode Island. Since 1996 Save The Bay and the Barrington Conservation Commission’s Salt Marsh Working Group have been involved in advocating for the restoration of Walker Farm marsh.  Save The Bay involved the Natural Resources Conservation Service and NOAA in the restoration project. NRCS has provided funding for the construction of the restoration plan through the Wetlands Reserve Program.  National Oceanic Atmospheric Administration has provided funding for site assessment, prerestoration monitoring and design, engineering, and construction.  The State of Rhode Island’s Coastal Resources Management Council Habitat Restoration Fund also provided funds for restoration construction. Ducks Unlimited provided design engineering, construction oversight and construction funding. ESS, a local environmental consulting firm has conducted the permitting.


Restoration Design and Construction

Construction occurred in the summer of 2005.  The restoration project included modifying three existing tidal restrictions to improve flushing of the salt marsh.  The southern structure includes water control structures to increase tidal flow.  The structure under the access road was increased in size to allow for more tidal flow into the marsh interior.  The former farm roads were removed from the marsh surface to improve tidal circulation within the salt marsh.  The northern restriction also includes a water control structure.  Analysis by URI of the marsh sediment determined that a large amount of sediment would be lost from the marsh if the tidal restoration was removed completely.  To address the potential loss of marsh substrate, the northern restriction was designed with a water control structure to limit the initial tidal flow into the marsh.  As the marsh revegetates, the water control structure can be modified to allow for greater tidal flow.  The marsh spoils were placed in the upland adjacent to the marsh and planted with a conservation mix.  A water control structure management plan will be developed based on monitoring trials during spring low and high tides.  The water control structures will be maintained by the Town of Barrington in consultation with NOAA, NRCS, Ducks Unlimited, and Save The Bay.


Monitoring

Save The Bay monitored soil salinity, groundwater elevation, vegetation, and fish usage of the marsh for several summers prior to restoration. Results confirmed that plant and animal communities were significantly impacted by tidal restrictions and road fill.  High water temperatures and reduction in the duration of tidal inundation of the marsh surface limited the use of this historic salt marsh by many fish species (monitored with the help of Narragansett Bay Research Reserve staff).  Vegetation monitoring showed that Phragmites australis was the dominant plant species and replaced native salt marsh vegetation. Monitoring following restoration has shown promising results. The diversity of fish species using the marsh has nearly doubled.  Phragmites height has decreased, likely in response to the introduction of more salt water.  The area covered by Phragmites has stopped increasing, and is expected to begin decreasing this summer.  Native low and high marsh plants are continuing to colonize the marsh in greater density. Results did show that only the smallest fish remained on the marsh at low tide, since nearly all the water was drained.  In response, the project partners agreed to make changes to the tide gate to allow some water to remain in the marsh at low tide. Monitoring this summer will show if this adaptive management was effective at improving the fish habitat.

Project partners include the Town of Barrington, Save The Bay, USDA Natural Resources Conservation Service, the National Oceanic and Atmospheric Administration’s Community-based Restoration Program, Restore America’s Estuaries, Ducks Unlimited, RI Coastal Resources Management Council, RIDEM Mosquito Abatement program, URI Department of Natural Resource Sciences, Narragansett Bay National Estuarine Research Reserve, ESS Group, VHB Inc. and RI Corporate Wetlands Restoration Partnership.

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