Tapping the aquifer—at what cost?

Buried extent of the Lower Tuscan Aquifer system in the northern Sacramento Valley.

Buried extent of the Lower Tuscan Aquifer system in the northern Sacramento Valley.

Is the Lower Tuscan Aquifer—the vast underground lake that provides Chico and nearby communities with their drinking water—in danger? Are irrigation districts profiting from selling surface water at inflated prices and then replacing it with pumped groundwater?

Such questions were being asked last Friday (June 9), when the Sacramento Valley Environmental Watershed Caucus held a forum at the Chico City Council chambers downtown. One of the speakers was SVEWC’s Jim Brobeck.

“Several schemes are unfolding to inject our groundwater into the state water supply,” Brobeck charged, “and they are doing so without the science, without the knowledge of what these major transfers will do to the aquifer.”

Brobeck’s distrust is not without cause. Back in 1994, under the blessing of the Department of Water Resources (DWR), the Western Canal and Richvale irrigation districts sold the rights to 105,000 acre-feet of “surface” water to Southern California. To make up for it, the districts tapped the aquifer.

1994 was a drought year, however, and once the districts started pumping, wells in Durham began to “suck air.”

Brobeck insisted it’s happening again.

“The Western Canal District, which straddles Butte and Glenn counties, gave notice that they will test Measure G [a water sales ordinance] by applying for a permit to sell some of their surface water to the desert community of Palmdale for $135 an acre-foot,” stated Brobeck. “And how does WD intend to replace this water? By pumping the aquifer.”

Calls to the Western Canal District were not returned.

In another charge, Brobeck said the Glenn-Colusa Irrigation district (GCID) had hired a consultant to apply for a taxpayer-funded grant that would definitively “wed the Lower Tuscan Aquifer to the state water supply.”

“That is not true,” said Thad Bettner, general manager of the GCID, in a later phone interview. “Yes, we hired a consultant for grant writing, and we are looking at the Lower Tuscan for various opportunities, but we are not hiring consultants for water transfers. … Agriculture does not benefit if we transfer water south.”

When reminded of the ‘94 water sale during a drought year, Bettner responded, “1994 was a learning experience for all. That was a crisis mode, and no one wants to see that happen again.”

In 1994, after the Durham dry-well incident, Butte County supervisors pushed for major studies of the Lower Tuscan. Twelve years later, no studies exist, though data is being gathered.

“We have 60 monitoring wells throughout the Tuscan that are collecting data every hour,” said another forum speaker, the DWR’s Dan McManus. “The kind of fear and distrust that exists [among the various users of the aquifer] is good. It allows for due diligence. There’s no advantage to anyone to dewater the aquifer to the point that it becomes less effective.”

“It would take three years, great resources, and cooperation among several agencies to conduct a thorough study of the aquifer,” stated Dr. Lev Kavvas, a UC Davis professor who discussed his successful computer water modeling at the forum. “You already have a tremendous amount of uncertainty to the water supply of the Butte basin.”

Which brings us back to Brobeck: “It seems crazy to me to take more water out of the system before science is conducted.”