Nantucket Island is broken down into a number of individual watersheds. A watershed is an area of land that is up gradient of a water resource area. Rain water, irrigation water, and septic system runoff percolates through the sandy soil to the groundwater which will ultimately flow to a final down gradient water body. Wetland systems such as smaller ponds and vegetated wet meadows will also receive water from the upgradient source and depending on its location in the watershed will then in turn be a source for the down gradient water body such as an estuary or a harbor.
Which Watershed Do You Live In?
Land owners need to be extremely careful about their fertilizer applications, septic systems and other land uses in order to limit the amount of pollution entering the groundwater. The map below delineates Nantucket’s watersheds. Learn more about the watershed where you live by clicking on the area in which you reside.
Capaum and Washing Ponds are small waterbodies at 20 acres and 8 acres respectively. The Capaum Pond watershed is approximately 82 acres and the Washing Pond watershed only 32 acres. Recreational use of the ponds is negligible due to their small size and restricted access. Land use within these watersheds that may impact the ponds includes residential development, septic systems, and fertilizer use.
Hither Creek is a semi-confined body of water opening to Madaket Harbor and connected to Long Pond via the Madaket Ditch. Hither Creek is 40 acres with a surrounding watershed of approximately 419 acres, while the adjacent Madaket Harbor watershed is much larger. The Creek is tidally influenced, but its long and narrow configuration limits circulation and flushing. During the summer a high density of boats moor in the Creek with a commercial boatyard and small residential lots abutting its shores. A shallow depth to ground water surrounding the Creek increases the potential of salt water intrusion to nearby drinking wells as well as increases the potential for pollutants from septic systems and fertilizer reaching the Creek.
Hummock Pond extends from the south shore northward to the interior of the island. Extensive conservation land abuts the shorelines of Hummock Pond and Clark’s Cove. Land uses in other areas of the watershed include residential homes, septic systems, drinking water wells, food crops, and horse pastures.
Long Pond stretched from the southwest shoreline almost to the north shore of the island. It is connected to Hither Creek via the Madaket Ditch. Long Pond is surrounded by a number of closely settled residential lots with septic systems and private wells, and the town Landfill is located on the eastern shore. Long Pond is 132 acres with a watershed of approximately 1,620 acres. A significant amount of conservation land surrounds the Pond, buffering some of the potential land use impacts.
Miacomet Pond is a 37 acre water body, while its surrounding watershed is 26 times larger than the pond itself at approximately 1,009 acres. A tremendous volume of groundwater, stream flow, and surface runoff floods the pond to excessive levels during seasons of high precipitation. The water level rises into yards, basements, and roads that have been constructed within the flood zone.
Nantucket Harbor’s watershed encompasses the island’s northeast quadrant. It is semi-enclosed with a channel connection to Nantucket Sound. Circulation and flushing is limited in the upper harbor and in Polpis Harbor. The watershed’s west end is heavily developed commercially and residentially, serviced by public water and public sewer. In the center and east end, land uses include residential homes with mixed sewer and individual septic systems, wells, highly maintained landscapes, and conservation land. Water uses include swimming, fishing, boating, and shore-side services to support those industries. Nantucket Harbor’s federally designated No Discharge Zone prohibits boat sewage from being discharged into the harbor. Direct discharge of storm drain runoff still occurs and carries sediment and pollutants that contribute to the degradation of harbor water quality and shellfish habitat.
Tom Nevers Pond is located southeast of Tom Nevers Road. It is connected to Gibbs Pond by Phillips Run through a series of wetlands. The watershed contains undisturbed wetland and upland areas, managed golf course, residential development on septic systems, and agriculture. Most of the extensive wetland system is an actively managed commercial cranberry bog. The watershed recharge area is close to 100 times larger than the pond itself. Nutrient loading and pesticide runoff are pollutant risks to Tom Nevers Pond.