 Thirty-two river boards inherited the functions of the existing catchment boards, or took over the flood prevention functions on main rivers from local authorities where no catchment board existed.The exceptions were the River Thames Catchment Board and the Lee Conservancy Catchment Board, which continued to exist under the powers of the 1930 Act.River authorities were created by the Water Resources Act 1963 (1963 C. 38), which became law on 31 July 1963.