Bala
In the late 1950s the Bala Lake Scheme was promoted to increase the available water for abstraction in the River Dee. Telford's original sluices were by-passed and the natural lake outlet was lowered . New sluice gates were constructed downstream of the confluence with the Afon Tryweryn, which is only a short distance from the lake exit. This provided 18 million cubic metres of stored water in Bala Lake that could be controlled and used on a seasonal basis for low-flow regulation. This enables continuous abstraction from the River Dee of 235,000 cubic metres per day by six statutory water undertakings and British Waterways Board. An additional benefit was a reduction in flooding events downstream of Bala as Bala Lake was able to contain the worst of the winter flood peaks.
Read more about this topic: Dee Regulation Scheme