New Jersey’s Dam Safety Standards (N.J.A.C. 7:20) are administered by the NJDEP’s Division of Dam Safety and Flood Engineering, and they impose complex requirements on the owners of New Jersey’s dams. But who the owner of a dam is in New Jersey and thus obligated to comply with these regulations, and even whether the NJDEP has the authority to enforce these standards, was the subject of contentious litigation in the past. The statutory authority for these regulations extends back to an act adopted in 1912 that gave the State Water Supply Commission authority over the construction and maintenance of some dams in New Jersey; this law was amended in 1981 and became known as the Safe Dam Act.

The Safe Dam Act (L 1981, c. 249, or N.J.S.A. 58-4) and the associated Dam Safety Standards are settled law now, and the owners of existing dams in New Jersey are obligated to periodically inspect and maintain their dams. Although the DEP’s Division of Dam Safety and Flood Engineering keeps an inventory of New Jersey’s dams, it is not available to the general public for security reasons. However, the U.S. Army Corps of Engineers (USACE) keeps a National Inventory of Dams (NID) which can be accessed, and currently includes 834 dams in New Jersey. The NJDEP’s inventory includes many more dams (currently 1,729), because the DEP recently added a fourth category of dams (Class IV – Small Dams) in addition to the three classifications of dams included in both the NJDEP and USACE inventories: Class I – High Hazard, Class II – Significant Hazard, and Class III – Low Hazard Potential.

Although the NID has only partial records for completion dates of the State’s 834 dams, approximately 25 percent of the dams that do have a completion date were built prior to 1920, and are thus more than 100 years old (including 53 dams built from the 1600s through the 1800s). Many of the older dams in New Jersey were built in conjunction with roadways across streams or as sources of power for local mills. When they were originally built, it’s likely they provided adequate flood protection, but subsequent development has changed the upstream hydrologic conditions for most of these dams. Between increased discharge for a given storm event due to changes from forest or agricultural to suburban or urban land use, and increased storm intensity due to climate change, many of the original spillways are no longer adequate to handle today’s peak discharges.

NJ’s dams must be inspected periodically by a NJ Professional Engineer (Class III and IV every four years, Class II every two years and Class I every one or two years). A Water Lowering Permit from the DEP’s Division of Fish and Wildlife must be obtained to partially or completely lower the water level of any lake, whether required for inspection or for rehabilitation of the dam. A Dam Permit from the DEP is required for rehabilitation or replacement of an existing dam or spillway, or construction of a new dam. If a stream is used for migratory fish, consultation with the Division of Fish and Wildlife will be required as part of the Dam Permit application.

Churchill has been working with the DEP’s Division of Dam Safety and Flood Engineering on dam inspections, studies, designs and renovations for decades, and can guide the owner of any NJ dam to keep them in compliance with the applicable State and Federal standards.