In June of 1937 the Missouri was sent surging though tunnels, into the spillway, and out of its ancient riverbed. Construction of the dam continued through hot summers, frigid winters and frozen machinery. In September of 1938 a half a mile stretch of the dam slid out into the newly-forming lake with little warning, taking one hundred and thirty four workers, railroad track, and supplies with it. News traveled quickly to the boomtowns as workers rushed to warn their families downstream to move to higher ground. Upon investigation the landslide was caused by a weakness in the foundation bedrock.