Tuesday, August 18, 2026

Question: What year did Lake Powell begin filling?

Answer: 1963. Crews closed Glen Canyon Dam’s two diversion tunnels on March 13, and the Colorado River began backing up into the reservoir. Filling took 17 years. The reservoir did not reach full pool of 3,700 feet until June 22, 1980, at a capacity of more than 25 million acre-feet.