Upon completion of the controversial Glen Canyon Dam in 1963, Lake Powell slowly began to fill, rising out of the canyon created by the Colorado River. Work on the Glen Canyon Dam Project took seven years and the creation of the lake formed what is now the Glen Canyon Recreation Area, established in 1972. It took 17 years for the lake to be completely filled and was named after Major John Wesley Powell, a one-armed veteran who served during the Civil War. In 1869, Major Powell led the Powell Geographic Expedition, a three month journey down the Colorado River and the Green River. His passage through the Grand Canyon was the first known exploration of the Canyon.The lake extends for 186 miles with the shoreline taking up over 1900 miles. At capacity, the lake can hold up to seven trillion gallons of water. Currently, with recent low water levels of the lake, visitors to the region can see parts of the Glen Canyon once lost to rising water. Powell is only second in size to Lake Mead in Nevada/Arizona.