Marion County Lake developed through a sequence of key events from 1934 to 1942: an election was held on November 6, 1934; camp moved in on February 3, 1936; the plan was approved on August 9, 1936; the gate was closed on June 17, 1937; the first state fish came in March 1938; the first county fish came on April 20, 1938; the lake level reached a high elevation of 133.3 on June 24, 1938; the gate opened at elevation 127.3 on November 25, 1938; the gate closed at elevation 115.75 on November 30, 1938; the dam was accepted on March 21, 1939; camp moved out from February 1-15, 1939; buildings were removed on May 8, 1939; the lake level reached a high elevation of 136.35 on August 15, 1939; the lake opened for fishing on May 26, 1940; water went over the spillway on September 6, 1941; ice broke the valve tower on January 12, 1942; the valve opened on January 14, 1942; the tower was repaired in March 1942; and the lake filed from the tower on September 6, 1942.