Lake Powell exists because of the Glen Canyon Dam which generates electricity and regulates the water used by Utah, Arizona, California, and Nevada. The tour was fun, even in the rain. The bridge next to the bridge, however, was very cool because it was built in Emeryville, CA, and trucked over here to Arizona. When they put in the final connectors between the two halves of the bridge, it was only off by 1/4 inch.
I found it interesting that it took 17 years to fill Lake Powell after the dam was built in 1963. Each year they have to allow a certain amount through for each state that uses the water and when all of that is finished, they keep back water to fill the lake.