As Texas’ rivers run dry and lakes fall to record low levels, part of the fight over water supplies is moving underground.

Neighbors who pump water from the same formations beneath their land have long argued over that water. But the stakes are rising as cities and industries see groundwater as a solution to the demands of explosive population growth.

But Texas law governing groundwater is murky, and a recent state appeals court decision signals that only years of expensive legal battles will provide clarity.

“This whole issue will ultimately be resolved by litigation and not legislation,” said Andrew Sansom, executive director of the Meadows Center for Water and the Environment at Texas State University.