For more than a century, a collection of deals, treaties and legal agreements have divided up the Colorado River’s water, a vital supply for 40 million people, seven states in the U.S. and two in Mexico, 30 federally recognized tribal nations and 5.5 million acres of agriculture.

Arizona will again go without 18% of its total Colorado River allocation, while Mexico loses 5%. The reduction for Nevada — which receives far less water than Arizona, California or Mexico — will stay at 7%. California won’t face any cuts because it has senior water rights and is the last to lose in times of shortage.

Federal officials announced Friday they would continue water allocation cuts on the Colorado River for the fifth consecutive year following a persistent drought that’s shrunken the river’s largest reservoir.