Water supplies to some US states and Mexico will be cut to avoid "catastrophic collapse" of the Colorado River, Washington officials said Tuesday, as a historic drought bites.

More than two decades of well below average rainfall have left the river—the lifeblood of the western United States—at critical levels, as human-caused climate change worsens the natural drought cycle.

Despite years of warnings and a deadline imposed by Washington, states that depend on the river have not managed to agree on a plan to cut their usage, and on Tuesday, the federal government said it was stepping in.