For New Mexico, a lot is at stake.
Though Texas also named Colorado in the suit, its real target is New Mexico. Texas alleges that by allowing farmers in southern New Mexico to pump groundwater connected to the river, the state is unfairly taking water from the Rio Grande that, under the 1938 Rio Grande Compact, should be flowing to Texas.
When Texas filed a similar suit against New Mexico about the Pecos River, the case dragged on for almost two decades, and cost both states millions of dollars.
Were Texas to win the Rio Grande case, it could force some southern New Mexico cotton, pecan and chile farmers to stop pumping groundwater. Or, the state could even wind up paying up to $1 billion in damages, according to the Associated Press.
New Mexico filed a motion to dismiss the case, but the U.S. Supreme Court’s special master—appointed to research the issues and report to the court—recommended the court reject that motion and allow the case to proceed.
One entity from the state absent from the list is the Elephant Butte Irrigation District, which sits below the dam in New Mexico, but in the legal world of western water, is considered a part of Texas.