In 1720 an act of Parliament was passed allowing Thomas Steers and William Squire to make the Douglas navigable to small ships between Wigan and its mouth. Amid financial irregularities, the Douglas Navigation was not completed until 1742, and by 1783, it had been superseded by the Leeds and Liverpool Canal. It reverted to being a river, although the remains of several locks can still be seen between Parbold and Gathurst. The Rufford Branch of the canal joins the river at Tarleton. The river rises on Winter Hill on the West Pennine Moors, and flows for 35 miles (56 km) through several towns and onto the Ribble estuary past Tarleton, the last 10 miles (16 km) or so being tidal. In 1892 the Douglas was diverted in Wigan to allow the construction of Wigan Central railway station.