A dry spell
Butte County groundwater levels at historic lows
Don’t let the recent rains fool you—it’s been a dry year in Butte County. Or, perhaps more accurately, it’s been a dry decade.
During a forum in the packed Chico City Council chambers on Nov. 14, representatives from the city of Chico, Butte County and the local water-advocacy group AquAlliance outlined the current state of the county’s groundwater system and potential threats to its health, including climate change and the state’s controversial Bay Delta Conservation Plan.
Speaker Christina Buck, a water-resource scientist for the Butte County Department of Water and Resource Conservation, explained that about two-thirds of the water the county uses comes from rivers, streams and lakes, while the other third is groundwater drawn from the Tuscan Aquifer. As indicated by measurements of six local water wells that have been monitored since the 1940s, the county’s groundwater levels have been in decline for decades, Buck said. The water levels of those wells are currently at “historic lows,” while dozens of wells with monitors installed more recently have triggered low-water alerts based on levels recorded in a shorter timeframe.
Dry conditions over the last dozen years have most likely played a part. In terms of annual precipitation, there have been two “wet” years—2006 and 2011—in the past 12, while the rest were below average or in the drought category. The amount of water drawn from the aquifer for human use is also a major factor. About 90 percent of water used in Butte County is for agricultural purposes, while urban use and environmental projects account for the rest.
Durham-area farmer Ed McLaughlin offered a ground-level perspective on Butte County’s groundwater issues. Due to the enormous amount of water required for agriculture, McLaughlin said, there is a common perception that farmers “use water excessively.” Because overdrawing the Tuscan Aquifer affects all county residents—not just farmers—McLaughlin championed a “nonpartisan balance” in which “everyone would share the burden” of proper water-resource management.
As several speakers did throughout the evening, McLaughlin pointed south to the San Joaquin Valley—an area responsible for the majority of the state’s agricultural exports, which bring in an estimated $30 billion annually—as an example of how irresponsible groundwater management could affect Butte County. Due to subsidence—the gradual or sudden sinking of the surface of the ground, attributed to excessive water pumping—certain areas of the San Joaquin Valley have sunk dozens of feet over the last century.
“Don’t think that can’t happen here,” McLaughlin warned.
Since Butte County began measuring for subsidence in 1999, there has been no measurable change in ground level. However, Buck emphasized the importance of further understanding how the Tuscan Aquifer recharges and how much water can be safely drawn from it in order to avoid the San Joaquin Valley’s mistakes.
Buck suggested looking to other areas of California that have been more proactive than Butte County in terms of groundwater management. One such option is “managed aquifer recharge,” which, according to the Bay Delta Conservation Plan, involves man-made infrastructure or landscape modifications to enhance the natural groundwater-recharge process. There is such a project currently being monitored in the Resource Conservation District of Santa Cruz County.
“We can’t keep hoping for wet years,” Buck said. “We know water demands are greater than what we’ve gotten from these below-normal and drought years.”
Later in the forum, Buck spoke at length concerning a major threat to the county’s groundwater levels: drought due to climate change.
California’s place along a jet stream makes long-term changes in annual precipitation due to climate change difficult to project, Buck said, though “drought is definitely a threat, and there’s not a lot we can do to control that.”
While future precipitation levels are unpredictable, it’s certain that average temperatures are trending upward, Buck said, which will impact how much precipitation falls either as snow or rain. Less snowfall in the Sierra Nevada mountains would have huge implications for water management, as reservoirs such as Shasta Lake and Lake Oroville were “designed to manage snow runoff.”
Barbara Vlamis, executive director of AquAlliance, highlighted another potential threat to local groundwater—the Bay Delta Conservation Plan backed by Gov. Jerry Brown’s office. The plan includes a pair of 35-mile-long tunnels to divert water from the Sacramento-San Joaquin Delta south for agricultural use, and would cost an estimated $25 billion.
Vlamis anticipates that diverting so much of the North State’s water to points south will only further stress Butte County’s groundwater supply.
“[The tunnels] will drain our wallets and devastate our water resources,” she said. “It’s horrendous to even think about.”