The village of Mardale was flooded in 1935 to create Haweswater reservoir to provide for the needs of Manchester. When water levels are really low the walls of Mardale reappear. Helen Mark meets Booker-nominated novelist Sarah Hall to talk about the power the landscape has had on her writing, including her first novel, Haweswater. Helen joins Ian Winfield from the Centre for Hydrology and Ecology as his team count the fish in the lake using hydroacoustic equipment. Haweswater is now managed to protect the rare Shelley and Arctic Char which are found in its waters. John Gorst from United Utilities explains that the fish are recovering in numbers since it was realised that low lake levels in summer were having a detrimental effect on their ability to breed. Helen also meets Spike Webb from the RSPB in the only valley in England which is a permanent home to a golden eagle.