Geist Reservoir is a reservoir in Lawrence, Indiana, U.S., constructed in 1943 by damming Fall Creek to provide water for Indianapolis. Upon completion, Geist Reservoir was the second largest man made lake in Indiana providing approximately seven billion gallons of water.
Geist ReservoirDam is located at the lake's southern end. Fed by Fall Creek on the north, the lake overflow is directed into the creek again at the south. The earthen dam is 44 feet high, with a length of 1400 feet at its crest. The reservoir capacity is 60,000 acre-feet, although normal storage is 21,180 acre feet.