Lechlade in the context of "Cotswold District"

The head of navigation is the farthest point above the mouth of a river that can be navigated by ships. Determining the head of navigation can be subjective on many streams, as the point may vary greatly with the size or the draft of the ship being contemplated for navigation and the seasonal water level. On others, it is quite objective, being caused by a waterfall, a low bridge that is not a drawbridge, or a dam without navigation locks. Several rivers in a region may have their heads of navigation along a line called the fall line.

Longer rivers such as the River Thames may have several heads of navigation depending on the size of the vessel. In the case of the Thames, that includes London Bridge, which historically served as the head of navigation for tall ships; Osney Bridge in Oxford, which has the lowest headroom of any bridge on the Thames that generally restricts navigation to smaller vessels such as narrowboats and cabin cruisers, and the long reach above St John's Lock, the first lock downstream of the river’s source, on the outskirts of Lechlade, where the river can become treacherously narrow and shallow for anything but small motorboats and human-powered vessels.

St John's Lock, below the town of Lechlade, Gloucestershire, is the furthest upstream lock on the River Thames in England. The name of the lock derives from a priory that was established nearby in 1250, but which no longer exists. The lock was built of stone in 1790 by the Thames Navigation Commission.

The main weir is downstream, just below St John's Bridge, where the River Cole and the River Leach join the Thames on opposite banks.

Water transport played a vital role in the UK's industrial development. The beginning of the 19th century saw a move from roads to waterways, (i.e. canals, rivers, firths, and estuaries).