London Authority, was intended to assess the impact of the CSO discharges into the Thames and to identify objectives and propose potential solutions, while keeping costs and benefits in mind. Outcomes After four years, the Thames Tideway Strategic Study report was published in 2005, and outlined the following objectives: To protect the ecology of the Tideway; To reduce aesthetic pollution due to sewage-derived litter; and Protect the health of recreational water users Potential strategies Four potential strategies were discussed: Adoption of source control and sustainable urban drainage; Separation of foul and surface drainage and local storage; Screening, storage or treatment at the discharge point to river; and In-river treatment After superficial evaluation of alternatives it was decided that only one strategy, the screening, storage or treatment at the point of discharge, would meet the estuary objectives fully. The remainder were found to be either impractical or insufficient to provide a solution, although the evidence from the outer London Boroughs is that separated storm drainage can sustainably prevent all pollution. In a 2006 report commissioned for Ofwat, Jacobs Babtie strongly recommended using the computer model of the existing system to do detailed studies of the effects of laying separate storm water pipes, but their advice and that from Ofwat in 2007 concerning the poor value of the tunnel was not followed. A number of parties questioned the integrity of the TTSS study, in particular the dismissal of separation and future SUDs/blue-green infrastructure as a solution. Some groups that opposed the tunnel stated that it is an unsustainable 19th-century solution to a 21st-century problem. They argued that rainwater from roads should be sent directly to canals, rivers or the estuary, and that landowners could install soakaways for their roof run off, making them eligible for discounted water treatment bills. This would reduce pressure on the foul system and take away the need for the tunnel. In November 2010 the draft National Policy Statement for Waste Water (NPSWW) was issued, and eventually published largely unaltered, despite Parliamentary objections that it promoted the Tideway Tunnel as the only solution. Screening, storage and treatment The three-part solution to implement screening, storage and treatment was collectively known as the London Tideway Improvements. Stratford to Beckton: Lee Tunnel This earliest phase was the Lee Tunnel: a deep, broad storage and conveyance tunnel dug and lined from Jenkins Lane, Beckton to Abbey Mills, Stratford, sloping down the reverse