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.

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 formerly 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

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

Permitting

in 2006 permitting began in earnest for the restoration of the pond..  site visits were held, plans were submitted and revised, hearings convened.  The project design went through many stages and input from a variety of sources was sought and received.  As this progressed Three Bays Preservation continued water quality monitoring.  Also on going at this time was as a result of this monitoring was the preparation of a Mass Estuaries Project Report for Rushy Marsh, released in 2007?? place URL.  This report This report led to the creation of a Total Maximum Daily Load for the pond, this report can be viewed at ++place URL.  This report recommended that in order to restore Rushy Marsh the pond be reconnected to Nantucket Sound via a culvert in order to improve water quality.  This was the best method of restoration and recommended over conventional sewering to improve the health of this embayment.

In 2013 with the permitting completed for the restoration of Rushy Marsh with the installation of a culvert to reconnect the pond to Nantucket Sound contracts were bid and construction began.  Utilities were buried, a precast culvert was installed, two channels were dug and a stone jetty was installed.  All was ready for the reconnection to the sea.