Drammankin Lake, (AUDIO: Innocence) colloquially known as the Lake of Mutations, was a polluted body of water on Skaro near a mountain range. It was home to mutations created by the use of chemical and biological weapons during the Thousand Year War. (AUDIO: Corruption)
Nasgard's family lived in a villa by the lakeside for generations. During his childhood, his stepson Davros spent much time by the lake studying the creatures within it. (AUDIO: Innocence) Skaro's natural ecosystem was devastated by the war and the lake eventually became one of the few places on Skaro where animal life could survive. (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 for cooling purposes. (TV: "The Expedition") The Daleks also kept their anti-missile rockets beneath the waters of the lake. (COMIC: Impasse, The Terrorkon Harvest)
The Dalek Prime conducted numerous experiments on other creatures of Skaro after the end of the Thousand Year War. Those that survived the experiments went on to inhabit both the lake and the petrified forest, adding to the number of mutations already living there. (PROSE: The Evil of the Daleks)
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 while looking for food. 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.
During this time, Ian broke off from the main group to wash his face, and he witnessed one of the creatures lift themselves out of the lake, but he managed to escape before they attacked. (TV: "The Expedition")