Economist Milton Friedman is often credited with noting, “If you put the federal government in charge of the Sahara Desert, in five years there’d be a shortage of sand.” State governments haven’t done much better managing the Colorado River. On Thursday, the Colorado Basin River Forecast Center, which is part of the National Weather Service, offered a grim outlook for the summer . After a dry winter, Colorado River flows into Lake Powell will be just 13 percent of average. That would be the lowest amount since the Glen Canyon Dam , which created Lake Powell, was finished in 1963. Lake Powell is upstream of Lake Mead. As Las Vegas residents can see, Lake Mead’s water levels keep falling . This isn’t a one-year problem. The seven states along the Colorado River have long been using more water than the river reliably provides . The Colorado River Compact of 1922 allocated too much water from the start. Climate trends and the Southwest’s extended drought haven’t helped.…