The Whippany River is a tributary of the Rockaway River, approximately 20 mi (30 km) long, in northern New Jersey in the United States. It rises in Morris County, in Mendham Township west of Morristown, and flows generally ENE in a meandering course, through Morristown and the Whippany area of Hanover. It flows through the Troy Meadows and joins the Rockaway in the Hatfield Swamp in eastern Morris County, just above the confluence of the Rockaway with the Passaic River. The river drainage area is 69 square miles (180 km2). There are three USGS water gauges on the river. The ... Source: Wikipedia