Under the rusty cliffs of Marble Canyon, the start of the Grand Canyon in Arizona, a nondescript river measurement gauge has been tracking the flow of the Colorado River for decades. … The Colorado River’s flows at the gauge, called Lees Ferry, are fundamental to water sharing agreements among upstream states, like Colorado, and downstream states including Arizona, California and Nevada. If the river’s flow falls too low, the three downstream states can raise a ruckus, arguing the upstream states are breaking century-old agreements and forcing the basin into a legal mire that might only be decided in the U.S. Supreme Court. 

Other Colorado River management news:

• Lake Powell Chronicle (Miami, Ariz.): The 2.3 million-acre-foot reality​​