A pond’s watershed is the area of land that contributes water to the pond. The slope of the surrounding upland determines the area that contributes surface runoff, while the shape of the water table determines the movement of water within the aquifer.

In the western, hilly areas of the Vineyard, the soil is developed on impervious clay and till. Seepage through this kind of soil is very slow, and aquifers may be confined to pockets or beds of sandy material. In such cases (including Menemsha Pond, James Pond, and Daggett's Pond), the watershed is defined more by topography. The south shore, and the north shore east of Tashmoo, have very sandy soils, so the watersheds there are determined more by the groundwater flow. In 2015, the MVC adopted an Islandwide watershed map to outline the boundaries of each watershed.

The watersheds also define areas where pollutants entering the ground may eventually affect coastal pond water quality. Nitrogen from wastewater disposal, fertilization, and stormwater runoff are the primary sources. The watershed map is the starting point for determining how development may affect the ponds.

Up-Island 208 - Watershed Management Plans

A multi-year Up-Island Watershed Management Plan is nearing completion, with the final sections having been prepared for review by the MA Dept. of Environmental Protection (DEP), which is funding the project. The plan covers the watersheds of Chilmark Pond, James Pond, Menemsha Pond, Squibnocket Pond, and Tisbury Great Pond.

Having a 208 plan will give the towns more choice in dealing with nutrient overload in their coastal ponds, rather than having the state dictate its own solutions, which could be more costly for taxpayers. It also qualifies each community for inclusion in the Cape Cod and Islands Water Protection Fund, which provides funding for water quality projects in the region.

Chilmark Lower and Upper Watersheds

• Existing Conditions (Chilmark)
• Existing Conditions Appendix (Chilmark)
• Watershed Habitat Restoration (Chilmark)

James Pond Watershed

• Existing Conditions (James Pond)
• Existing Conditions Appendix (James Pond)
• Watershed Habitat Restoration (James Pond)

Menemsha Pond Watershed

• Existing Conditions (Menemsha Pond)
• Existing Conditions Appendix (Menemsha Pond)
• Watershed Habitat Restoration (Menemsha Pond)

Squibnocket Pond Watershed

• Existing Conditions (Squibnocket Pond)
• Existing Conditions Appendix (Squibnocket Pond)
• Watershed Habitat Restoration (Squibnocket Pond)

Tisbury Great Pond Watershed

• Existing Conditions (Tisbury Great Pond)
• Existing Conditions Appendix (Tisbury Great Pond)
• Watershed Habitat Restoration (Tisbury Great Pond)

Potential Solutions Report - For all five Up-Island watersheds.

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