Habitat Restoration & Protection Database

Background: The Barn Island Wildlife Management Area is a 1020-acre site that is owned by the State of Connecticut, approximately 30% of which is tidal marsh. A dike was constructed across most of the Barn Island marshes in the mid-1940s as a means to enhance open water habitat for migratory waterfowl, shorebirds, wading birds and muskrat. Open water habitat (pannes, pools, and tidal ponds) declined in tidal marshes as a result of mosquito ditching in the early 1930s, and the dike offset these losses by trapping water on the upstream side. The final section dike was constructed in 1968. Given the layout of the Barn Island tidal marsh system, the dike, which connects a series of north-south running forested headlands, created impoundments of water on the upstream side. These were labeled Impoundments 1 - 5, going from west to east. In 1970, the dike was rebuilt and water control structures were installed to reintroduce some tidal influence in order to help with the mosquito breeding and Phragmites problems. At this point, however, Impoundment 2a was still completely cut off from tidal exchange. Problem at Impoundment 2a: A small, interior, pocket tidal marsh within the Barn Island Wildlife Management Area known as the Impoundment 2a marsh had become degraded after several decades of insufficient tidal exchange. The existing 12-inch diameter culvert did not convey enough tidal water beyond the Barn Island dike road and into the 2a marsh. As a result, the marsh became saturated and brackish. Vegetation died off in these saturated areas, leaving patches of mud flats. Shallow depressions that held water also formed, yet marsh fish were precluded from accessing these small ponds and pannes. Unnaturally high levels of mosquito breeding resulted, and monotypic clones of invasive Phragmites australis became established. The Barn Island Impoundment 2a tidal marsh bounded by the Barn Island dike road to the south, and a horseshoe-shaped upland area surrounds the remainder of the marsh.