The project was halted when the United States entered World War II and resources were needed elsewhere. In 1941, Harry Athey suggested to President Franklin Roosevelt that the canal could be converted into an underground highway or a bomb shelter with its roof for landing airplanes. The whole idea was deemed impractical due to the river's periodic flooding. In 1942, freshets destroyed the rewatered sections of the canal. National Park Service (NPS) official Arthur E. Demaray pressed that the canal from Dam #1 be restored, to supply water to the Dalecarlia Reservoir in case sabotage or bombing destroyed the normal conduits of water. Since this transformed the canal into a concern of national security, in 1942, the War Production Board approved the work. By 1943, Congress had funded the work, repairs were done, and the Park Service resumed boat trips in October 1943.