in 1974, the rivers committee, which had managed the site since its inception, ceased to be, when water and sewage treatment became the responsibility of the newly formed north west water authority. the organisation was subsequently privatised, and became part of united utilities in 1995. in order to meet demands for better water quality, a pilot biostyr plant was built in 1992, and a much larger one was completed in 1998. innovation continued, with the commissioning of the world's largest thermal hydrolysis plant in 2013, using a new process to break down sludge, which generates methane as a by-product, enabling the site to be self-sufficient for gas and electricity. an upgrade to the activated sludge plant began in 2014, and is expected to be completed in 2018.