It was built in the 1960s, and used to be the supply of drinking water for the northern half of Anglesey. The lake lies in an open landscape and has a large car park. It is fringed with vegetation, and there is woodland and scrub along parts of the lake shores.

There is marshy grassland and scrub at the northern end of the lake, with exposed mud around the lake margins at lower water levels.

The reservoir has a number of small islands, and there are paths around the lake shore, but they do not form a complete circuit.