Llyn Brianne and the Upper Towy
Llyn Brianne and the Tywi Forest
Constructed in the 1970s, Llyn Brianne was designed to control the flow of the River Towy to enable consistent water extraction further downstream.
The dam is 299 feet high and 951 feet long, it is of crushed and larger rock clay filled construction. In 1996 the height of the spillway was increased by 3 feet and a hydro-electric plant built at the base of the dam, seen to the left of the spillway and in the picture below. The capacity of the dam was increased from 13,400million gallons to 14,200 million gallons. The normal flow is 1.5 million gallons a day during the summer driving a single turbine. During the winter and spring there are three turbines operating, producing 4.3 Megawatts of electricity. When the water in the dam is below the spillway, a plume of water comes from the turbines.
Only one unoccupied farmhouse, Fanog, was flooded when the dam was built.
The water from Llyn Brianne is very cold and many fishermen attribute this to the deterioration in the river's fish quality.
Looking down the spillway.
Llyn Brianne captures not only the waters of the Towy, but of the Camddwr and other minor tributaries creating the four arms of the reservoir.
The Towy as it enters Llyn Brianne but a few miles north it is little more than a stream fed by smaller streams cascading down the mountain sides
The upper Towy valley. The stream here marks the boundary between the counties of Powys and Ceredigion. The valley is one of the last refuges in Wales for the Red Squirrel.
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