Nevada sued the federal government on Monday to block officials from cutting its share of the Colorado River, launching the first major legal fight over the Southwest’s dwindling water supply. The state asked the U.S. District Court in Nevada to order the Bureau of Reclamation to rescind plans that would cut water allocations significantly for Nevada, California and Arizona over the next decade if the river basin continues to dry up.

Nevada argued the plans unfairly burden those three states while federal officials did not impose any mandatory water restrictions on four other states — Wyoming, Colorado, Utah and New Mexico — upstream. It said that the Reclamation Bureau, part of the Interior Department, violated a complex web of laws, agreements and court cases known as the law of the river, as well as other federal laws governing administrative procedure and environmental regulation.

Gov. Joe Lombardo stated, “The Department of the Interior can’t roll Nevada and solve the entire Colorado River shortage on the backs of the Lower Basin states.” The lawsuit targets a longer-term plan issued last month that calls for potentially more severe actions to limit the lower basin states’ water use from 2029 through 2036. Officials said the state’s share of the river could shrink by 70 percent, even though Nevada has taken steps to cut its water use by 40 percent.

Interior officials declined to comment. Mark Squillace, a law professor at the University of Colorado, noted the lawsuit avoids the feared quagmire of states suing one another.