Originally, Haweswater was a natural lake about 2.6 miles long, almost divided in two by a tongue of land at Measand; the two reaches of the lake were known as High Water and Low Water. The building of the dam raised the water level by 95 feet and created a reservoir four miles long and around half a mile wide. When the reservoir is full, it holds 84 billion litres (18.6 billion gallons) of water.
When the dam was constucted it used cutting edge technology at the time being the first hollow buttress dam in the world!
Lake District writer and fell walker Alfred Wainwright had this to say on the construction of the Haweswater dam in his Pictorial Guide to the Far Eastern Lakeland Fells:
"If we can accept as absolutely necessary the conversion of Haweswater [to a reservoir], then it must be conceded that Manchester have done the job as unobtrusively as possible. Mardale is still a noble valley. But man works with such clumsy hands! Gone for ever are the quiet wooded bays and shingly shores that nature had fashioned so sweetly in the Haweswater of old; how aggressively ugly is the tidemark of the new Haweswater!".
Coordinates 54°31′08″N 2°48′17″W