The River Thames has been a transport route for centuries, and Wallingford's growth as a town relied partly on it. Coal was supplied from North East England by coaster to London and then by barge upriver to Wallingford. This supply could be unreliable in seasons when river currents were too strong or water levels were too low. In 1789 the Oxford Canal reached Oxford from Warwickshire, and the Duke's Cut at Wolvercote gave it a connection to the Thames. This allowed coal from the Midlands to reach Wallingford by a shorter and more reliable route than by sea and river from the northeast. In 1799 the Oxford Canal consolidated its commercial position by buying an 80-year lease on a wharf on the Thames just above Wallingford Bridge. Chalmore Lock, a summer or low-water lock and weir, was built at Chalmore Hole, Wallingford in 1838, However, much of the time the fall was only 18 inches, and the lock was open at both ends. It fell into disrepair, and the lock was removed in 1883. The missing lock is the subject of confusion in Jerome K. Jerome's "Three Men in a Boat". A ferry had operated at the site from 1787 to transport horses across the river where the towpath changed banks. As the removal of the lock and weir meant that this was the longest clear stretch of the upper river, it was an ideal site for rowing, so the Oxford University Boat Club which had long trained here built a boathouse at Chalmore in 2006. In addition to the old Wallingford Bridge, a new bridge was built at Winterbrook in 1993 to carry the A4130 bypass around Wallingford.