Harwich Water Department Water Quality

Monomoy Lens - Focus on: Harwich Groundwater Protection

This map shows the Monomoy Lens water table in 10 foot contour levels

Prepared by the
Water Resources Office
Cape Cod Commission
for the Harwich Water Department
January 1998

Cape Cod is fortunate to have an abundant supply of high quality drinking water. This brochure answers frequently asked questions about groundwater and discusses potential impacts from population growth on drinking water supplies. The information is intended to familiarize residents of the town of harwich with local drinking water supply sources and what is being done to ensure they will remain safe for years to come.

Where does the water supply originate?
The Monomoy Lens is the source of fresh water for the town of Harwich. This lens is one of the six groundwater lenses that make up the Cape Cod Sole Source Aquifer. Lenses can be thought of as mounds of groundwater bordered by marine water at the edge, bedrock on the bottom, and separated from each other by tidal waters, such as Bass River, that cut across the Cape peninsula. Groundwater refers to subsurface water in soils and geologic formations that are fully saturated.

Groundwater in the Monomoy Lens is replenished from rain or snow that seeps into the ground. The water percolates through the soil to reach the water table which is the surface of the groundwater lens. Water within the lens slowly moves toward the coast where it discharges into the ocean. Along the way, groundwater flows into the numerous kettlehole lakes and ponds, and into streams feeding marine embayments along the coast.

The map below shows the location of the Harwich public drinking water supplies. The shaded areas represent the land area where the groundwater flows toward the well instead of moving all the way to the shore. These areas are referred to as recharge areas, wellhead protection areas, or, if state approved, Zone II's. Recharge areas for wells located in Dennis, Brewster, and Chatham that cross the Harwich town boundaries are also show.

Harwich Public Supply Wells

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