on 1 april 1974, the rivers department and the rivers committee ceased to exist, when responsibility for the works passed from manchester city council to the newly formed north west water authority. the authority built a new control room in 1981, which housed a computer control system for the site. three years later, eight new sludge digesters were built, to enable all sludge dumped at sea to be digested first. construction of the mersey valley regional sludge pipeline began, linking oldham to davyhulme, and continuing to sandon dock in liverpool. davyhulme was able to treat sludge from a number of other sewage works to the east, and pump the digested product to liverpool. sludge boats ceased to use the ship canal, taking 15 minutes to transport sludge from liverpool to a point to the north of the bar light in the mersey, instead of over six hours required when using the canal.