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Rushy
Marsh Pond Restoration Project
Reopening a Connection to the Sea
The Conservation Division of the Town of Barnstable has been investigating
the reopening of a connection to the sea from Rushy Marsh Pond in
Cotuit, the stated goal being to improve tidal exchange with Nantucket
Sound in order to address water quality issues while protecting
environmental values.
Three Bays Preservation, in partnership with the Friends of Rushy
Marsh Pond, is now aiding in evaluating the feasibility of the project
by building on a study completed by the town in March 2002 and filling
in data gaps on two issues that were not adequately addressed in
that study: What are the nutrient levels of the pond, and what is
the movement of the sand on the beach?
 Jason
Eldredge (left) and Chris Adams, profiling the beach at low tide.
Nutrient Analysis
Our investigation of the nutrient levels in the pond was initiated
late summer of 2002 through our water quality monitoring program,
and has resumed each spring. Efforts aimed at pond restoration have
been linked to the Massachusetts Estuaries Project nitrogen management,
assessment and modeling effort. Rushy Marsh was included in the
most recent prioritization and the work is being "fast tracked"
to coincide with the on-going engineering program. As part of the
Estuaries Project, measurements of nitrogen inputs and losses are
being made as well as analysis of the present habitat quality within
the Pond, including animal and plant communities and continuous
records of dissolved oxygen. This information is then coupled to
the design of the new tidal "inlet" to re-establish the
natural resources, currently impaired by the restricted tidal exchange
and nutrient load. The coupling of the engineering and habitat restoration
efforts brings additional resources to the project, through the
State's matching support via the Massachusetts Estuaries Project.
A Shifting Shoreline
Rushy Marsh Pond lies in a dynamic coastal setting, and more than
two centuries of historical maps show a constantly changing shoreline
and the closing of the natural inlet to the pond around 1910. If
we are to attempt to reopen the connection, we must first understand
how the sands are shifting today to evaluate how difficult it will
be to keep a channel open once installed.
One way to obtain information about seasonal and storm-induced
beach shapes is to profile the beach monthly, with additional profiles
taken immediately before and after major storms. Our study of beach
movement through the process of beach profiling was initiated in
December 2002 with the assistance of Jim O'Connell of the Woods
Hole Oceanographic Institution Sea Grant Program and Cape Cod Cooperative
Extension, and is accomplished by recording elevations of the dunes
and beach, and graphing the changes to those elevations over time.
Comparing profiles season-to-season clearly illustrates the important
changes taking place along the shoreline and how quickly coastal
landforms change.
As we accumulate data, we’ll be better able to evaluate whether
the culvert is physically possible and, once opened, if there will
be sufficient tidal exchange to improve the water quality in the
pond.
Typical Dune Profile
A Typical Dune and Beach Profile
Courtesy of WHOI Sea Grant Program, 2001, Marine Extension Bulletin
“Beach and Dune Profiles: An Educational Tool for Observing
and Comparing Dynamic Coastal Environments” by Jim O’Connell |
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