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Allen Harbor - Little Mussachuck - Sachuest

Little Mussachuck Creek Marsh Restoration, Barrington

Site History | Planning | Construction | Monitoring | Benefits | Lessons Learned

In a true show of community-based restoration, Save The Bay and the Barrington Conservation Land Trust set out to restore a tidally restricted marsh in Narragansett Bay. With all permits and technical expertsí recommendations in hand, in April of 1998, Save The Bay directed a corps of over 70 volunteers to restore tidal flow to Little Mussachuck Creek, a salt and brackish wetland located in upper Narragansett Bay.

The Barrington Conservation Land Trust, the owner and steward of the marsh, had been monitoring the expansion of common reed (Phragmites australis) since the mid 1990s and had seen a significant increase in its spread at the expense of other plant species, many of which were species of statewide concern. The Land Trust believed that rare native brackish marsh plants were in danger of extirpation at the site due to the continued expansion of the invasive Phragmites in the northern portion of the marsh. The Land Trust sought the expertise of Save The Bay to coordinate the restoration of Little Mussachuck Creek in 1997. The objectives of the restoration project were to evaluate a range of restoration alternatives and carry out a restoration action that would conserve rare wetland plants: creeping spikerush (Eleocharis rostellata), maritime sea blite (Suaeda maritima), salt marsh bulrush (Scirpus maritimus), and leafy bulrush (Scirpus robustus).

Aerial photo of Little Mussachuck Creek marsh (click to enlarge)
Aerial photo of Little Mussachuck Creek marsh (click to enlarge)
Courtesy: Save The Bay

Site History
Like most back barrier marshes, Little Mussachuck Creek marsh formed in response to changes in sea level and localized effects of barrier beach migration, storm overwash events, shifts in tidal inlet positions, and changes in biogeochemical processes. The marsh consists of approximately 25 acres of estuarine salt and brackish wetlands and approximately 10 acres of open water and mudflat habitats. The western edge of the marsh is bounded by a narrow barrier beach, Annawamscutt Beach, which separates the wetland from Narragansett Bay. Little Mussachuck Creek empties into Narragansett Bay at its southern end where it forms an ebb/flood-tide delta. A tidal inlet historically connected the northern portion of the marsh to Narragansett Bay. The closure of this tidal inlet has been the focus of this restoration.

Ecological Impacts
The build up of beach sands in the northern part of the barrier beach had begun restricting the northern inlet to Little Mussachuck Creek by 1990. By 1998, this tidal inlet was completely cut off from daily tidal influence. At Little Mussachuck Creek, the mean long shore deposition is in a northerly direction. This is evident by observed deposition patterns in the beach. Longshore deposition processes are a coastal geologic phenomena that influence the structure of barrier beaches, resulting in the distribution and movement of sediment along the shoreline. Longshore processes are caused by the interaction of tidal currents, prevailing wind patterns, and beach geomorphology. Longshore currents are believed to be impacted by the severity of shoreline hardening by sea walls and bulkheads owned by property owners adjacent to Little Mussachuck Creek. One particular sea wall extends perpendicular to the barrier beach and acts as a trap for sediment carried in longshore currents.

Save The Bay and members of the RI Habitat Restoration Team visited Little Mussachuck Creek in 1997 to evaluate restoration options. The group agreed that disruption of longshore sedimentation had altered the barrier beach of Little Mussachuck Creek. Closure of the northern inlet was believed to be the likely impetus for Phragmites invasion and consequent changes in the marsh plant community. The inlet closure had resulted in the impoundment of fresh water in the northern portion of the marsh, flooding salt marsh species, and allowing Phragmites to gain a foothold. The closure of the northern tidal inlet changed the upper marsh from a characteristic high salinity emergent wetland to a fresh and brackish pond with infrequent tidal inputs. Concurrent changes in water chemistry and a reduction in tidal signal have been followed by the colonization of the marsh by monotypic stands of Phragmites. Additionally, continued inundation by fresh water had deteriorated the high salt marsh peat adjacent to the flooded pond. This had the potential to lead to marsh subsidence.

Restoration Planning
Save The Bay and the Land Trust were fortunate to work with the R.I. Habitat Restoration Team, composed of technical experts from U.S. Fish and Wildlife Service (USFWS), the Rhode Island Department of Environmental Management (DEM) and the University of Rhode Island (URI). The team assisted in the evaluation of the restoration options for restoring Little Mussachuck Creek marsh. The decision to restore tidal hydrology to northern portions of Little Mussachuck Creek was based on careful deliberation and recommendations by state and regional salt marsh restoration technical expertise. The Barrington Land Conservation Trustís preferred restoration alternative was determined by acquiring technical resources from the following groups.

  • Tom Steinke. Fairfield, Connecticut Conservation Department. Summer 1995 site visit.

    Recommendation: Create a connector ditch from the existing creek to the northern pond.

  • Rhode Island Habitat Restoration Advisory Committee, Salt Marsh Work Group. The group included leading wetland scientists from URI including Dr. Frank Golet as well as Brown University, U.S. Environmental Protection Agency (EPA), USFWS, DEM, and RI Coastal Resources Management Council (CRMC). They visited the site during the summer of 1997.

    Recommendation: Excavate a new channel from Little Mussachuck creek to the salt panne and create a sill ditch from the salt panne to the northern pond.

  • Barrington Conservation Commission Salt Marsh Working Group. In winter 1997, Little Mussachuck Creek was identified as one of the highest ranked marshes for restoration, as evaluated through quantitative prioritization and assessment of potential restoration projects in Barrington.

    Recommendation: Evaluate restoration alternatives and decisively implement restoration actions to conserve rare and sensitive plant species.

Three alternatives were developed for U.S. Army Corps of Engineers Section 404 permit requirements:

  1. no-build option
  2. breaching the barrier beach
  3. restoring tidal connection between the creek and pond

The preferred alternative selected by the restoration team was to restore tidal hydrology to the northern marsh and pond complex by excavating connector channels to the existing tidal channel draining to the southern inlet. The new channel was engineered to maintain surface water in upper brackish pond, allow fresh surface water to drain out of the pond, and to convey tidal inputs into the pond during spring high tides. This approach represented the best long term sustainable option for restoring tidal hydrology to the northern pond of the marsh, stemming the invasion of Phragmites by increasing salinity levels, and protecting threatened populations of creeping spikerush (Eleocharis rostellata), salt marsh bulrush (Scirpus maritimus), leafy bulrush (S. robustus), and maritime sea blight (Suaeda maritima).

Volunteers digging a 300-foot channel in Little Mussachuck Creek marsh
Volunteers digging a 300-foot channel in Little Mussachuck Creek marsh
Courtesy: Save The Bay

The shovels hit the peat in April 1998
Permits were received from DEM, CRMC and the U.S. Army Corps of Engineers. The Barrington Conservation Land Trust received a Partners in Wildlife grant from USFWS to create a restoration tool bank of shovels, scythes, boots and other equipment for this and future community-based restoration projects. Armed with shovels, milk crates, and buckets, close to 100 volunteers, ranging from local high school students to retired engineers dug a 300-foot creek connecting the restricted section of the marsh to the unrestricted section of marsh leading to Narragansett Bay. Even the Governor of Rhode Island, Lincoln Almond, donned boots to visit the work site.

While the volunteers dug the creek, Save The Bay staff used a laser level to check the depth and width of the creek to ensure the proper creek geometry. The volunteers who participated in this project were forewarned that this would be hard, wet, and dirty work, and not a soul complained as they dug and hauled hundreds of pounds of saturated peat and Phragmites rhizomes for the entire project. Phragmites was composted in a covered and secured location on a farm field adjacent to the marsh.

Restoration Monitoring
Four transects were set up in the upper northern portion of the marsh to best characterize expected changes in plant community structure following restoration actions. The four transects were randomly located across this area of the marsh using a random numbers table. Transects were all positioned along a perpendicular gradient from upland soil to tidal creek or open water (Figure 1).

    Vegetation. Save The Bay's Andy Lipsky and Wenley Ferguson collected Mussachuck creek vegetation data in September 1998. Total plant species (grasses, forbs, shrubs, trees) were identified and relative cover determined using a line intercept method. Every 0.25-meter section per 1-meter or 2-meter interval was sampled. Relative cover along the 0.25-meter linear was allowed to exceed 100 percent due to overlapping species cover. Click to open the data in an Excel spreadsheet.

    Biogeochemistry and Hydrology. Distance of plot to open water was determined with meter tape. Shallow wells (55 cm depth), constructed from 3-inch diameter PVC with 1/8-inch pores and open on the bottom, were constructed and deployed during spring 1998 to measure porewater salinity within the active plant root system. Three wells were installed along each transect, placed randomly within three distinct zones: upland, high marsh, and low marsh (Figure 2).

    Porewater salinity was recorded with a hand refractometer during spring and neap tides with an effort to sample at the time of low tide. Sampling occurred randomly throughout the1998 growing season. Data was collected by Save the Bay (STB) staff, interns, and trained volunteers. Water levels were noted only when water elevations dropped below the measurable length of well or when tide-water levels rose above the well top. Wells were not installed in Transect 4. A surface water collection station located in the upper pond in the vicinity of Transect 4 served as a proxy for porewater salinity for Transect 4. Because this upper marsh never exceeded oligohaline (0.5 to 10 practical salinity units) levels, porewater salinity in subsurface soils of Transect 4 was believed to follow surface water variation. Click to open the data in an Excel spreadsheet.

    Phragmites Height and Distribution. Permanent quadrats were located within Transects 2 and 3 in an established Phragmites community. In each quadrat (0.5-meter square rectangular), live and dead Phragmites shoots were counted and measured for 12 randomly selected shoots. Permanent photo stations were set up at Transects 2 and 3 to monitor Phragmites height over time. To measure lateral growth of Phragmites along the leading edge of the stand, oak markers were set in 1998 at approximately 10-meter intervals. Each year, the distance of the leading edge of the most forward above ground Phragmites shoot is measured from the 1998 oak stake (Figure 3). Photo-stations are established at key locations to document the height and spread of Phragmites.

Benefits of the Restoration
Today the meandering creek carries the fresh water out to Narragansett Bay and carries the Bayís salty waters into the marsh during spring high tides. Phragmites remains a dominant member of the plant community at Little Mussachuck Creek and future actions will be based upon upcoming monitoring. Erosion at the southern end of the marsh has increased in the past four years and will be addressed in future management decisions.

Little Mussachuck Creek marsh, June 2001
Little Mussachuck Creek marsh, June 2001
Courtesy: NOAA

The marsh, once flooded with fresh water, now reveals mud flats which creeping spikerush and salt marsh bulrush began to colonize during the first growing season. These same mud flats have provided feeding habitat for shorebirds including greater and lesser yellowlegs, semipalmated plovers, glossy ibis, great egrets, and snowy egrets. Mummichogs, silversides, anadromous herring, and American eels have all been observed using the new channel to access upstream marsh and open water habitats.

Lessons Learned - Community Involvement and Monitoring Plan
Many, if not most, marsh restoration projects are too large a scale for an on-the-ground volunteer project. Yet this project proved that volunteer involvement can occur at every stage of restoration, from conducting restoration monitoring and attending planning meetings, to channel digging, hauling out buckets of muck, transplanting salt marsh sod, and conducting post-restoration monitoring.

Community members and volunteer monitors played an integral role in the restoration project.

At the early stages of the project, community involvement was solicited to ensure that local residents were both educated and aware of the benefits, potential costs, and the value of restoration. Local citizens provided valuable information about the history of the marsh. Local knowledge was key to identifying what, how, and when disturbances occurred to the marsh and what plants and animals used to be found in the marsh. Volunteer monitors have gathered important data that is now being used to determine adaptive management actions at Little Mussachuck Creek. As proven by the Little Mussachuck Creek restoration, a group of dedicated and hard-working volunteers with the proper guidance and expertise can make a marsh restoration project a reality.

It is has been important to establish a realistic monitoring plan and schedule that can be easily conducted with available expertise and resources. Permanent photo stations have been a simple yet effective way to monitor long-term changes in the marsh, specifically the coverage, height, and density of Phragmites. STB staff, interns, and experienced community volunteers conducted intensive vegetation sampling. This intensive sampling was conducted in 1998 and 1999 with the next scheduled monitoring to occur in 2002. Unfortunately, at the time of the restoration, monitoring guidelines had not been developed for Rhode Island salt marsh restoration projects. Since the development of the monitoring methods, efforts have been underway to develop consistent monitoring guidelines for restoration projects throughout the state.

Next Steps
The restoration approach taken thus far has been to act, monitor, and evaluate. The underlying issue of sedimentation, erosion, and human alteration of the shoreline continues to remain an outstanding issue at the site. In 2002, Save The Bay and the Barrington Conservation Land Trust will evaluate the performance of our actions so far. In order to do this we will review vegetative and hydrologic data, reconvene a technical advisory team, and pursue any recommended adaptive management actions. Future phases of the restoration effort may incorporate the need to maintain or enhance the existing tidal inlet, control Phragmites abundance with other control methods, and obtain coastal geologic expertise to develop a long-term management plan for the site and adjacent shoreline properties.

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This site was created through a partnership of the:

Coastal Resources Management Council
Narragansett Bay Estuary Program
Save The Bay®