Faced with yet another outside scheme which would bypass the navigation from Wakefield to Ferrybridge, the company looked at improvements which would give of water all the way to both Leeds and Wakefield. Thomas Telford surveyed both routes, and it became the basis for an act of Parliament which was passed in June 1828. It included a clause to ensure that the Selby Canal was maintained with a depth of water of , and made provision for extensions to Goole docks. Work started on a new cut at Castleford and on the line to Leeds, but legal action over the Selby Canal meant that it had to be made deeper and wider in 1832 and 1833. The Leeds line was completed in April 1835, somewhat later than anticipated, as the banks were made more substantial, to cope with steam tugs, which would be introduced in due course. The seven locks above Castelford were all wide. Improvements to the Calder to Wakefield took longer, as there were problems with floods filling the workings, difficulty with constructing foundations for an aqueduct which would carry the navigation over the River Calder at Stanley Ferry, and then in transporting the castings for the aqueduct to the site. The cost of the improvements ran to around £510,000.