I especially like the information on Nantucket Island's Watersheds and Water Protection http://www.nantucketlandcouncil.org/WaterProt.html
"The Nantucket Land Council has mapped all the watersheds on Nantucket. You can find out which body of water, for example Madaket Harbor or Hummock Pond, the water under your house is flowing toward. Call us for a watershed map & brochure, or see it online at www.nantucketlandcouncil.org." She the
Watershed Map: http://www.nantucketlandcouncil.org/WtrShedMap.html
Your Lawn, Our Water
When rain falls, or when you irrigate your garden, excess fertilizers and pesticides will leach down into our sandy soils, eventually flowing into the ocean, a harbor, a pond or a drinking water well. The direction of the water flow on your property determines which “watershed” area you live in.