Water Quality

A watershed is the entire area of land and surface water that drains to a common body of water such as a lake, stream, or ocean. Thus, a watershed contains not only preserved land areas, such as the Great Swamp National Wildlife Refuge, but also the land upon which we build our homes, schools, businesses, roads, parking lots, and more. Through everyday activities such as fertilizing lawns, driving, walking pets, and improperly disposing of wastes (litter), pollutants accumulate on the land surface. When it rains, those pollutants are then washed directly into the closest stream, or indirectly through storm drains. Thus, in order to protect our water resources, we must also protect our land resources.

The Great Swamp watershed covers nearly 35,000 acres or 55 square miles, and is located within portions of ten different towns (Map of Great Swamp watershed) and two counties. The towns range from the heavily developed regional center of Morristown, to the suburban towns of Chatham, Bernards, Long Hill, Morris Township, and Madison, to the more rural towns of Bernardsville, Harding and the Mendhams (Borough and Township). Approximately 3,179 acres, or 9%, of the watershed was covered by impervious surface cover (ISC) as of 1995 (Map of impervious surfaces). Over 10,000 acres, or 28%, of the watershed remains as open space.

Five tributaries or feeder streams convey water from where it falls on higher elevations of the watershed (850 feet above sea level at its highest point) down to the much lower elevations of the Great Swamp National Wildlife Refuge (around 220 feet above sea level). Once in the swamp, four of the five streams merge and then join with the Passaic River and exit the watershed at the Millington Gorge (Map of Great Swamp watershed).

Watersheds and Sub Watersheds