Attorneys have wrapped up a marathon 25-day trial in which Montana sought to hold neighboring Wyoming liable for taking too much water from the Yellowstone River basin.
An initial decision is expected in mid-2014 from the U.S. Supreme Court appointee overseeing the dispute. The high court will have the final say.
Montana claims Wyoming has violated an interstate agreement 10 times since 1981 by taking more than its share of water from the Tongue River, a Yellowstone tributary. The state says that's left farmers' fields dry.
Wyoming counters that Montana officials formally requested more water only twice. In both instances, attorneys for Wyoming argue that there was no clear evidence of harm.
Farmers and ranchers on both sides of the border are dependent on the Tongue River for irrigation.