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Improving water quality at Town Neck Beach, Sandwich, Massachusetts

How Conservation Works

Mill Creek snakes its way through verdant marsh grass and out into sparkling Sandwich Harbor. This is a salt marsh, a coastal wetland that is a transition between the upland and the ocean. It's a fertile area for wildlife and shellfish, and it’s an important resource for the town of Sandwich, Massachusetts on Cape Cod. Water quality is critical here.

An historic board walk crosses the marsh, leading to Town Neck Beach with its white sand and sweeping view of Cape Cod Bay. The black aquaculture baskets floating in Mill Creek are a symbol of Cape Cod’s multi-million-dollar oyster industry, which includes recreational and commercial wild harvest.

“During the 1980s, water quality had degraded so significantly that the state closed the shellfish area,” explained Sam Jensen, Assistant Town Engineer for the Town of Sandwich.  “Bacteriological contaminants were high, and shellfish were no longer suitable for human consumption. It was discovered that septic systems from nearby homes and stormwater run-off from roads and parking lots were the main culprits.”

Town Neck Beach was wasn’t the only site on Cape Cod where stormwater run-off was affecting shellfish. Local, county and state officials identified 26 such sites in the early 2000s, along with 26 degraded salt marshes and 24 failing fish passages.  In partnership with the USDA Natural Resources Conservation Service (NRCS), the local and state officials developed a watershed-wide plan to address these concerns.

For the past decade, the Cape Cod Water Resources Restoration Project has provided federal funding and technical assistance through NRCS to improve water quality, restore salt marshes, and increase fish access to spawning habitat at those 76 sites.

“We found four locations here at Town Neck Beach where the stormwater runoff was controllable and impactful,” said Stephen Spear, Soil Conservationist for NRCS. “One of them is the boardwalk area and another is the beach parking lot.”

“The first flush of runoff from a parking lot or a roadway, particularly after a long dry period, contains about 85 percent fecal coliform and so we base our design criteria on treating that pollutant,” said Donald Liptack, Coastal Restoration Specialist with the Cape Cod Conservation District.

The project design included construction of retention areas comprised of sand filters with vegetation .  The surface runoff is retained in these areas as it slowly infiltrates into the ground. In the first flush of rainfall, soil particles and sediment containing bacteria are trapped by the sand filter and removed from the runoff.

“The channels are adjacent to the lowest area of the parking lot so that storm water can flow directly off the asphalt and collect in a small sediment basin for pre-treatment, and then it flows into the main treatment cell that contains sand and plants,” said Jensen. The combination of those elements treats the storm water before it either infiltrates into the ground or flows through a filtered outlet system to the adjacent marsh.”

“The value of a project like this and the whole Cape Cod Water Resources Restoration Project is to not only improve the environment but to support local farms and food production to hopefully add jobs in the area and to maintain this sort of seaside community way of life with recreational shellfish harvesting,” said Spear.