N.J. Stat. § 48:14-11
Every steam and water power company organized under the laws of this State may construct and maintain dams on rivers and streams at such points and at such heights as it may deem necessary or advisable, and may flow back and raise the water in the rivers or stream above the dam to a height not exceeding 10 feet above common low water of the rivers and streams.
The plans and construction of the dams shall be approved by the Department of Conservation and Economic Development. For dams on navigable streams, the department may require the construction of such canals, locks, gates, shoots or other openings as, after public hearing, it may determine that the interests of navigation require. Where judged necessary by it, the department may require all dams constructed under this article to be provided with a fishway for the passage of shad and other fish.
N.J.S. § 48:14-11