It's not as bad as it sounds, due to circumstances. The Gila runs into the Colorado right near downtown Yuma. The water flow to Mexico is a treaty item so any excess from the Gila would simply flow to the Gulf of California. It was use it or lose it stuff.

It has made an incredible agriculture enterprise possible. All your winter lettuce and a large fraction of your cotton and citrus is from Arizona (and the Imperial Valley of Cali. That canal runs right out of down town Yuma).