The lawsuit filed last week by the Havasupai Tribe seeking to halt groundwater withdrawals near the Grand Canyon’s South Rim is the first time the tribe has asserted its water rights, according to the tribe’s lawyer.

“Nobody has ever filed a lawsuit like this before,” Santa Fe-based attorney Richard Hughes said.

It was future plans for development, especially in the area around Tusayan, that spurred the tribe to take legal action, Tribal Chairman Don Watahomigie said.

“All we're saying is that you can go ahead with development if you can find other sources of water you're okay,” Watahomigie said in an interview last week. “We don't want any more drilling of water up on top on the plateau area where it’s going to deplete some of the springs and seeps we have down here.”

The Havasupai’s lawsuit asserts that a number of wells drawing from the Redwall-Muav aquifer, which runs deep beneath the Coconino Plateau, are threatening the springs and seeps that are the tribe’s sole water source deep in Grand Canyon. Several of the springs feed Havasu Creek, which runs through the village of Supai and creates the turquoise waterfalls that bring thousands of tourists to the Havasupai reservation each year, sustaining the tribe’s economy.

The lawsuit states that those canyon water sources are part of the tribe’s “aboriginal and federally reserved water rights” and that aquifer withdrawals by the 19 well owners named as defendants “constitutes a trespassory and unlawful interference with the Tribe’s water rights that threatens irreparable harm to the Tribe’s livelihood and cultural interests.”

If the court granted the relief the tribe seeks, it would mean that future appropriations of groundwater from the Redwall-Muav aquifer would not be allowed unless the tribe agreed to them, Hughes said.

While significant for the tribe, the lawsuit is also important in the broader scope of state water law because it marks yet another instance where it will be up to the courts to test and define Arizona’s conflicting groundwater and surface water laws, said Sarah Porter, director of the Kyl Center for Water Policy at Arizona State University’s Morrison Institute. Long-running adjudication processes in the Little Colorado and Gila river basins are trying to settle similar conflicts, Porter said.

Resolving cases like these can clarify the limits on  withdrawals and potentially stop years of unchecked drawdowns on a water system, Porter said.

Defining water threats

Hughes said he employed experts who refined U.S. Geological Survey water models to determine the threat of groundwater pumping on the Havasupai’s water resources.

“The model shows that eventually there will be a reduction in the flow, so the tribe’s position was it didn't want to wait until that was happening demonstrably,” Hughes said. “It needed to proceed now to get a declaration of its rights to the stream before it’s too late.”

Don Bills is one of the U.S. Geological Survey hydrologists who has been involved in measuring Havasu Creek’s flows for the past decade or more. Those measurements don’t yet suggest there has been any long-term impact from groundwater pumping, Bills said. At this point, the combined groundwater withdrawals from the Redwall-Muav aquifer within the watershed that includes Havasu Creek are just a fraction of the creek’s current flows -- less than 300 gallons per minute compared to the creek’s flows of 25,000 to 30,000 gallons per minute, Bills said. The biggest contributor to the minor long-term declines seen in the creek’s baseflow are more related to climate than groundwater withdrawals, he said.

But that doesn’t mean a reduction in flows due to groundwater pumping “can't happen tomorrow, a year from now or a decade from now,” Bills said. It all depends on development at elevations above the springs and seeps and how long it takes for a withdrawal of groundwater to migrate through the system, he said.

Emery Cowan can be reached at (928) 556-2250 or ecowan@azdailysun.com

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Emery Cowan writes about science, health and the environment for the Arizona Daily Sun, covering everything from forest restoration to endangered species recovery efforts.

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