Six years later, Wirt and two U.S.G.S. colleagues produced a more detailed report that said up to 86 percent of the Upper Verde comes from the Big Chino. To pin down the origins of the river water, she had water from the river’s springs, the Big Chino and other places in the area analyzed for elements such as lithium and boron that appeared in the rocks, and for various isotopes of hydrogen and oxygen, to date the water and determine how long had it taken for it to move from one spot to another.

Neither report was popular in Prescott, and the Arizona Department of Water Resources published a highly critical review of the first one. But in 2005, Department of Water Resources hydrologist Frank Corkhill wrote that the second study is a valuable reference tool for future research. In an e-mail this spring, he said Wirt’s 80 to 86 percent figure lies within the “possible range” of contributions from the Big Chino to the river.

Prescott and Prescott Valley last year commissioned a separate review of Wirt’s 2006 report. Prescott Valley water director John Munderloh said that though consultants found numerous errors and omissions in Wirt’s study, they didn’t take issue with the 80 to 86 percent figure. “It’s important to point out that the Laurie Wirt report isn’t an impact study. You can’t use that report to come to the conclusion” that the pipeline will dry up the river, Munderloh said.

 

Shortly before Wirt drowned last June, she warned — in public speeches and in private correspondence with pipeline critics — that she was concerned the pipeline would dry up the Verde. This drew criticism from pipeline supporters who felt she was stepping beyond the bounds of science.

Prescott officials asserted that the odds are low that pumping water from the Big Chino sub-basin will greatly impact the Verde, because the city-owned ranch where the pipeline will start lies 19 miles from the springs that feed the river. The city’s groundwater model predicted a water table decline of only 77 feet over 100 years, far too little to cause significant water-level reductions so far away, said Jim Holt, Prescott’s water resource manager.

The city and town are installing an extensive network of monitoring wells in the Big Chino Valley that will allow them to keep tabs on groundwater levels every 15 minutes. To reduce the pipeline’s effects, the city has also bought and retired 3,600 acre-feet of water rights historically used for area farms, Holt said.

But Jim Holway, a former state water official who was heavily involved in the Prescott disputes back in the 1990s, said he had little doubt that drawing down the Big Chino aquifer would have an effect on the river, particularly when the pipeline is combined with new housing developments pumping away in the area. “There’s only so much water there — we can’t both move it and develop there at the same time without creating a significant overdraft problem,” said Holway, now associate director at Arizona State University’s Global Institute for Sustainability.

Victoria Langenheim, a geophysicist who collaborated on Wirt’s second study, said she is sure the pipeline will eventually have an impact on the river. The question is when. “All the water level indicators do suggest that groundwater there is moving towards the river. If you pump water out of it, it will affect the springs,” she said. The pipeline proposal has sparked threats to sue from both the Center for Biological Diversity and the Salt River Project, a Phoenix utility that gets 30 to 40 percent of its surface water from the Verde and whose rights to the Verde date back a century.

In 2001, SRP President William Schrader wrote the mayors of Prescott, Prescott Valley and Chino Valley (which later dropped out of the pipeline project) that their plan was precipitous and unwise. “It is our intention to make you aware of our opposition to your pumping proposal right now,” Schrader wrote. “If you choose to continue on with construction of the pipeline, despite our express opposition to it, you will do so at the financial risk of the cities and towns.”

Today, Salt River Project officials say their basic legal stance hasn’t changed, although they don’t know when they might sue if the pipeline goes forward. They’ve installed a gauge at the river’s headwaters to monitor the river’s flow and have told Prescott officials it would be good to get a mitigation plan in place before they start pumping groundwater.

“The cone of depression (the area where the pumping of groundwater lowers the water table) is eventually going to reach the river — it’s just a matter of time,” said Dave Roberts, SRP’s manager for water rights and contracts. “As you withdraw more water, the cone just expands further and further outward from the place of pumping.”

Center for Biological Diversity officials say it will sue to protect Southwestern bald eagles living along the Verde and critical habitat for the threatened spikedace minnow, if Prescott-area cities get federal permits needed for the pipeline. Some of the center’s legal clout will depend on the success of two separate efforts in court: one seeks to prevent the U.S. Fish and Wildlife Service from delisting the Southwestern bald eagle when it removes the rest of the Lower 48’s eagle population from the endangered species list; the other would force the Service to list the roundtail chub that lives in the Upper Verde as endangered.

The group hopes, however, that Prescott and the other cities will work with the Service to produce a mitigation plan before the pipeline starts operations, said Michelle Harrington, the center’s rivers program director. “If they can pull together water that would go back into the aquifer to replace what they are taking out, if they can cobble together a plan that shows they are going to protect the aquifer and outflow to the river, then we wouldn’t have anything to fight them over,” Harrington said.

Since the lawsuit threats first surfaced, the pipeline furor has grown. The cost of the project has mounted from $30 million to more than $190 million, plus interest on bond sales. This year, Prescott officials acknowledged they still must acquire rights of way for the line from 160 property owners along the route. The right-of-way issue clouds the pipeline’s construction timetable, although officials said they still intend to open it in 2009.

County Supervisor Tom Thurman said he feels confident that the pipeline will not be stopped, but adds, “I never say never anymore.” If the pipeline isn’t built, the only way he can see Prescott ever coming into compliance with the state’s water laws would be to tell one-third of Yavapai County’s population to move out and bulldoze their homes.

“That is not feasible, of course,” he said.

The pipeline faces another obstacle. Its backers must prove to the state that the wells feeding the line will tap into an assured 100-year water supply. Such assurance will be difficult to make, given the presence of neighboring property owners who are eyeing Big Chino water, led by a Missouri investment firm that has asked the state to certify that water is available for the future development of the 30,000-acre CVCF ranch.