N.J. Stat. Ann. § 40:63-75

If such governing body or board shall, after such consideration, decide to join in the construction of the proposed improvement or works, it shall, by resolution, approve the surveys, maps, plans, reports, specifications and estimates so submitted to it, and cause the same to be filed with the clerk of the municipality, there to remain of record and a copy of the resolution of approval, certified by the municipal clerk, shall be served by him on the clerk of each of the other municipalities interested in the proposed improvement or works.