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A Watershed
A watershed is an area of land that drains downhill to a body of water, such as a stream, lake, river or wetland. A watershed includes both the waterway and the land that drains to it. Each watershed is separated topographically by a ridge or hill. A watershed is like a funnel - collecting all the water within the drainage area and channeling it into a waterway. Watersheds are natural bodies that don’t recognize political boundaries.
The Water Cycle
The water cycle, the oldest recycling system, is nature’s way of cleansing and reusing water in the environment. Water evaporates from the Earth’s surface and enters the atmosphere. It then returns to the surface as precipitation and becomes part of either surface water or ground water.
Surface water is the result of precipitation and runoff that enters bodies of water such as rivers, streams, lakes, and ponds. Ground water is the result of infiltration, the process by which water seeps into the ground, to be ultimately stored either in the pore spaces of soils or in pores or fractures in bedrock. In New Jersey, our drinking water comes from both surface and ground water.
The Stony Brook - Millstone Watershed
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Millstone Watershed Map - High Resolution (3 MB)
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The Millstone Watershed encompasses 265 square miles in central New Jersey. There are 26 municipalities within 5 counties included either entirely or partially in the watershed. The 38 mile long Millstone River begins in Millstone Township (Monmouth County) and flows north. The Stony Brook, a major tributary, runs 21 miles long with headwaters in East Amwell Township and flows eastward until it joins the Millstone at Carnegie Lake in Princeton. The Millstone continues north and eventually reaches the Raritan River, which empties into the Raritan Bay and the Atlantic Ocean.
Other tributaries of the Millstone River include Cranbury Brook, Rocky Brook and Beden Brook. The highest topographical features in the watershed include the Sourland Mountains which rise 568 ft above sea level, and the Princeton Ridge, a small spur in the center of the watershed. Carnegie Lake is the largest lake in the watershed, but there are a number of smaller lakes including Etra Lake.
