An operating agency shall, at the time of the construction of any dam or obstruction, construct and shall thereafter maintain and operate such fishways, fish protective facilities and hatcheries as the director of fish and wildlife finds necessary to permit anadromous fish to pass any dam or other obstruction operated by the operating agency or to replace fisheries damaged or destroyed by such dam or obstruction and an operating agency is further authorized to enter into contracts with the department of fish and wildlife to provide for the construction and/or operation of such fishways, facilities and hatcheries.