Colorado River running dry because of climate change?

Jonathan Waterman’s New York Times op-ed fails to make that case.

In “Where the Colorado Runs Dry,” Waterman asserts:

MOST visitors to the Hoover Dam and the Grand Canyon probably don’t realize that the mighty Colorado River, America’s most legendary white-water river, rarely reaches the sea.

Until 1998 the Colorado regularly flowed south along the Arizona-California border into a Mexican delta, irrigating farmlands and enriching a wealth of wildlife and flora before emptying into the Gulf of California.

But decades of population growth, climate change and damming in the American Southwest have now desiccated the river in its lowest reaches, turning a once-lush Mexican delta into a desert. The river’s demise began with the 1922 Colorado River Compact, a deal by seven western states to divide up its water. Eventually, Mexico was allotted just 10 percent of the flow…

Looking for back-up for the climate change assertion, the most Waterman can muster is:

… Demand for water isn’t the only problem. Climate change also threatens to reduce runoff by 10 to 30 percent by 2050, depending on how much the planet warms, according to a 2009 paper in Proceedings of the National Academy of Sciences…

Earth to Waterman, a future threat does not explain past change — not that we have much confidence in warmist projections of how future climate change may affect the Colorado River.