By understanding how what we do affects the quality and quantity of our water, we can take steps to insure that future generations will have drinking water and clean, healthy ponds and harbors. Ground water is the single source of drinking water on the island. It is also the principal source of fresh water for domestic, commercial and agricultural use. There is no nearby alternative drinking water supply if our aquifer becomes contaminated. Because of this, Nantucket has been designated a sole source aquifer by the U.S. Environmental Protection Agency.
Every resident lives in a watershed.
A watershed is an area of land where water flows from high elevations to low elevations, eventually making its way to a pond or harbor. Water may flow as surface runoff, streams, or seep into the soil and flow as ground water. Since ground water eventually discharges to a pond or harbor, it has tremendous influence on water level in ponds and water quality in ponds and harbors. Nantucket has an average annual precipitation of 44 inches. This water movement perpetually cycles between atmosphere and land.