Boulter's Lock

Boulter's Lock

Boulter's Lock as a pleasure boat squeezes in and under the bridge
Waterway	River Thames
County	Berkshire
Maintained by	Environment Agency
Operation	Hydraulic
First built	1772
Latest built	1912
Length	60.80 m (199 ft 6 in)
Width	6.47 m (21 ft 3 in)
Fall	2.39 m (7 ft 10 in)
Above sea level	77 feet (23 m)
Distance to Teddington Lock	31 miles (50 km)

Boulter's Lock is a lock and weir on the River Thames in England on the eastern side of Maidenhead, Berkshire. A lock was first built here by the Thames Navigation Commission in 1772. The lock is on the western side of the river between the main (A4094) Maidenhead to Cookham road and Ray Mill Island. The name is also used for the immediate surrounding area.

The weir is some way upstream of the lock, at the northern end of Ray Mill Island. It is one of the most popular whitewater freestyle kayaking areas on the River Thames, as it has been modified to allow kayakers to use it without causing disruption to other river users.

The earliest reference to a flash lock is in the late 16th century, although a mill is known to have existed here in the 14th century. The flash lock was located in what is now the main weir, with a winch to haul the barges through it on the west bank of the river near the tip of Boulter's Island. In 1746 it was written that there was no lock downstream of this lock. The Navigation Act obtained in April 1771 did not allow the Thames Navigation Commission to build locks below Maidenhead Bridge, so the lock built here in 1772 was the furthest downstream of the eight first built by the Commission. The lock was timber-sided, and the work was overseen by Joseph Nickalls, who had designed a scheme of improvements to the river from Abingdon to Richmond, in preparation for obtaining the Act of Parliament. Originally the lock was on the Taplow side, close to Taplow Mill, and in 1773 a nearby resident complained of trespass in his woods by the barge crews who "very much misbehaved themselves by their indecent conversation and horrid oaths and imprecations". It was referred to as "Boltus Lock". A "bolter" was a miller and hence the name means "miller's lock" and originally referred to the mill at Taplow. It was exceptional that a lock-keeper's house was built in 1774. By 1780 the lock was reported as being in as bad a state as Marlow, and in 1795 Phillips Inland Navigation complained of the deep hole and subsequent shoals caused by the force of water.