In the early 1600s, the River Aire was navigable to Knottingley, and boats carrying up to 30 tons traded on the river, which was tidal up to this point. The traders of Leeds were keen to have a navigable link to the town, to make easier the export of woollen cloth, but bills presented to Parliament in 1621 and 1625 had failed. William Pickering, who was mayor of Leeds, had made further attempts to obtain an act of Parliament for improvements to the river in 1679, again without success. As the 1600s drew to a close, a number of bills were passed for other rivers, and there was general support for river navigations. A bill was drawn up in 1698, with support from wool traders in Leeds and general merchants in Wakefield. John Hadley surveyed the Aire, and Samuel Shelton surveyed the Calder. Although the bill had a lot of support, it was opposed by the City of York, who feared that the River Ouse would be damaged by the scheme.