Rock Hole on Rahway River

Beginning in West Orange, the West Branch of the Rahway River flows south through South Mountain Reservation between the First and Second Watchung Mountains.

The West Branch is dammed in several places, forming a reservoir and small ponds. Structures along the Rahway River provide evidence of the region's industrial past.

For centuries, local community members have used the river for fishing and to power mills' waterwheels, such as gristmills, sawmills and cider mills. Many paper mills were built alongside the river, and one such mill is now known as the Paper Mill Playhouse. Other old mill relics can be found along the West Branch in the Reservation today.

South of the Reservation, the West Branch connects to the East Branch and leads out to the river mouth at Arthur Kill. The river provides water for local wildlife and fish, and fishing is popular along its length. Fish species include trout, bass, and catfish are present in the river. Natural plant communities can be found in the river's floodplains, including freshwater marshes and floodplain forests.