The Lake of Mutations, formerly known as Drammankin Lake, was an irradiated body of water on Skaro near a mountain range. It was home to mutations created by the use of chemical-biological weapons during the Thousand Year War.
Nasgard's family lived in a villa by the lakeside for generations. During his childhood, his son Davros spent much time by the lake, fascinated by the creatures within it. (AUDIO: Innocence) It eventually became one of the few places on Skaro where any animal life existed, as the war had made almost all species other than the Kaleds and the Thals extinct. (AUDIO: Corruption)
Years later, the Dalek City was built near the mountain range bordering the lake. Giant pipes ran directly through the mountains to the lake for the city's water supply. (TV: The Daleks) The Daleks also kept their anti-missile rockets beneath the waters of the lake. (COMIC: Impasse, The Terrorkon Harvest)
When the Monstrons' engibrains attacked and entombed the Dalek city, the Dalek Emperor fell into an underground river connected to the lake, where he was nearly attacked by a giant electric eel before being rescued. The eel was captured and used as the city's emergency power source. (COMIC: The Menace of the Monstrons)
Three members of the Thal party led by Ganatus were killed by creatures in the lake when they first discovered it. Ian Chesterton led a second trip around the lake to sneak into the city, during which another Thal, Elyon, was killed by one of the creatures. (TV: The Daleks)