The Bala bridge sluice gates were built for the Ellesmere Canal c.1804 as part of the water control scheme designed by William Jessop and Thomas Telford. They were designed to raise the level of Bala lake in summer by by one foot, ensuring that the canal would be constantly fed with water via the River Dee and the feeder canal starting at Llantysilio Weir (Horseshoe Falls). Later problems with flooding led to the sluice gates being lowered in 1808. The sluice gates were demolished as part of the Bala Lake Scheme implemented by the environment agency in the 1950's. This scheme re-routed the entire river channel next to Bala lake 100 metres north of the former sluice gates, a scheme which had originally been proposed by Jessop in 1803.

Rachel Leung, RCAHMW, 24 March 2010