The U.S. Supreme Court has denied Texas agency’s request to go into Oklahoma to obtain water.

While the water department that serves the Fort Worth area claimed it has the right to the water under the Red River Compact, an agreement that allocates water rights among states where the river flows, Oklahoma argued that its state law prevents the transfer of water to out-of-state applicants. In a unanimous decision the Supreme Court concluded that Texas has rights to water under the compact but cannot draw the water from Oklahoma.

Legal experts say the ruling will encourage other states to similarly restrict water supplies. With the drought in the Southwest continuing, battles over water are expected to heat up.

Along the same lines, hydraulic “fracking” to extract oil and natural gas across the southwestern states is driving up the costs of water for irrigation.