Lawyers for the Coachella Valley’s largest water districts and the Agua Caliente Band of Cahuilla Indians presented their arguments to a federal appeals court in a water rights case that could set a precedent for tribes across the country.

The case hinges on the question of whether the Agua Caliente tribe holds a federally granted “reserved right” to groundwater beneath its reservation in Palm Springs and surrounding areas.

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State supreme courts in Wyoming and Arizona have previously ruled on similar cases and have reached different conclusions, said Barton “Buzz” Thompson, Jr., a Stanford University law professor and water expert who isn’t involved in the Agua Caliente case.

“This is a very important case on an issue which is still, surprisingly in some ways, unresolved,” Thompson said. “This potentially could be a case that could go all the way to the U.S. Supreme Court.”

Thompson said he thinks the tribe has the stronger legal argument.

“There is a recognition today, that more and more states have built into their law, that there is really no difference between surface water and groundwater,” he said. “It is one hydrologic system.”