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The Removal of an 1800’s Agricultural Dike: Restoring Natural Tidal Hydrology at the Rachel Carson National Wildlife Refuge, Maine
Northeast Region, August 2, 2013
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The removal of the dike allows for natural tidal hydrology to occur.
The removal of the dike allows for natural tidal hydrology to occur. - Photo Credit: Rachel Carson NWR
After a few months plants are already starting to grow where the dike was removed.
After a few months plants are already starting to grow where the dike was removed. - Photo Credit: Rachel Carson NWR

Our east coast salt marshes are at the cross-roads of 300 years of intense human alterations and mounting stresses from climate change. At Rachel Carson NWR, the Land Management Research and Demonstration program is striving to restore our tidal marshes by eliminating harmful human impacts. Along the Mousam River in Kennebunk, Maine, one of these impacts is agricultural diking. In the late 1800s, farmers constructed a dike around a section of salt marsh to regulate tidal flows. This made it easier to harvest salt hay and graze cattle. However, over time, this dike, like others of its type, harmed the marsh by excluding natural tidal flows, reducing sediment deposition, and impounding water.
The Rachel Carson NWR has completed a 2-year effort to remove the Mousam dike and restore natural tidal hydrology. The dike had been located along the bank of the Mousam River creating a barrier between the river and adjacent salt marsh and also between the marsh and surrounding uplands. From 2011-2012, most of the dike was removed to grade level. Only a small section, subjected to high velocity flows along the river, remains. Now, tidal waters regularly flood and drain this marsh. In the future we expect water retention and subsidence to decrease, sediment deposition to resume, and native plant vigor to increase. It is our hope that by removing the impacts imposed by the dike, natural ecosystem processes will increase the salt marsh’s resilience to climate change stressors, resulting in greater longevity of the marsh and increased habitat value for salt marsh birds and other trust species.

 

For more information contact:
Susan C. Adamowicz, Ph.D.
LMRD Biologist Susan_adamowicz@fws.gov
Rachel Carson NWR
321 Port Rd.
Wells, ME 04090
207-646-9226 x31


Land Management Research and Demonstration website
http://www.fws.gov/northeast/rachelcarson/lmrd.html
Contact Info: Stephanie Petrus, 207-646-9226, stephanie_petrus@fws.gov



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