With its history of industry and farming, dams were built on the Raritan and its tributaries since the 1600s to supply water for private and municipal use, for agriculture, hydropower, water supply (canal), navigation (canal), fire suppression, to power mills, and for recreation including fishing, boating, and swimming. While some dams continue to serve specific purposes including water supply or flood control, many dams have outlived their useful lives and contribute to degradation of water quality and habitat. Depending on their construction and condition, dams can impede movement of resident and migratory fish and other aquatic organisms, restrict access to habitats, divide populations, and cause further decline of native populations (Craig et al. 2012). As noted by Craig, Goll and Shaw, “By converting a free-flowing river to an impounded one, dams dramatically alter the species composition of the aquatic community and lead to elevated water temperatures. They also interrupt sediment transport, which often causes geomorphic impacts downstream (i.e., incision, widening) and deprives instream habitat features of necessary sediment supply. Furthermore, sediment impounded behind a dam can create additional maintenance responsibilities (i.e., sediment dredging and lake management) and many affect flooding in adjacent residential area. Human communities are also directly affected by aging, obsolete dams [that] pose a drowning hazard, exacerbate upstream flooding, and are at risk of failure.”
Many of the 147 dams on the NJDEP’s inventory for the Raritan have outlived their useful lives or contribute to water quality or habitat degradation. This inventory doesn’t include dams under 5’ in height. There is no centralized inventory of smaller dams for the Raritan and no coordinated prioritization of dam removal for the Raritan region.