The next U.S. president will have to act quickly to chart a course so the Colorado River can continue supplying water to millions of city-dwellers, farmers, Indian tribes and recreational users in the Southwest, according to a university research study made public Monday.

A survey of policy- and decision-makers by the University of Colorado concluded that the president who takes office in 2017 could almost immediately face the prospect of Colorado River water supply cuts to Arizona and Nevada in January 2018.