Las Vegas Review Journal enthused that "the flow of last month ranked Powell's second largest lake at all in July. And 4350000 acre-feet of water flowing into the reservoir on the border of Utah, Arizona, in that month was nearly three times the July average , and the flow of the largest in June - 5400000 acre feet, or approximately 24 times the amount of water used in the valley of Las Vegas last year. "
Large snow melt and contribute to the delayed spring runoff in the summer and fill the lake. The paper reports that 21 in the state of Utah has the highest currents measured flows ever, with some records dating back 106 years. [Right, and Lake Powell in 2008 (top), compared to 1999 (bottom)]
And is also the Colorado River water through the channel of both the Central Arizona Project Phoenix and Tucson urban areas.