Sonoma Valley water supplies at risk
Sonoma County’s top water engineer warned members of the Sonoma Valley Citizens Advisory Commission that the Valley’s water supply is not immune to the effects of the State drought declared by the Governor last month. The extended lack of rainfall has put the local water supply “at risk,” as there is no new water to replenish the groundwater that is heavily used by residents and agriculture alike.
On Jan. 22, Jay Jasperse, P.E., chief water engineer for the Sonoma County Water Agency (SCWA), spent two hours going over the current state of the Sonoma Valley’s water supply which comes from the Sonoma Creek, existing groundwater and from the Russian River through a water pipe that runs down Highway 12 to the City of Sonoma.
SCWA and other water agencies have been preparing for a drought for years, but the reality is now setting in with the lowest rainfall in decades, if not longer, being registered this winter season.
“It’s very likely that Russian River supplies will be limited by this summer,” Jasperse told the Commissioners at their monthly meeting. He said his agency will be working with its contractors, which includes the Valley of the Moon Water District, to implement additional water conservation measures and water shortage contingency plans.
“Your water supply is less reliable than other parts of the county,” Jasperse said, noting that:
• It’s a long way to the Russian River.
• Pipelines are subject to natural hazards.
• Our groundwater aquifer is slow to recharge.
• Saline water is intruding at the southern end.
• Water use is increasing.
While the City of Sonoma and south valley residents typically use more Russian River water than north valley citizens, the pipeline provides the emergency backup to the Kenwood Village Water Company that supplies water to most residents of the village.
All of Sonoma Valley’s natural water comes from flow off the mountains that eventually goes to the Sonoma Creek and flows out to San Pablo Bay. Along the way, a good part of the water that falls on the ground seeps into the groundwater supply.
A United States Geological Survey of Sonoma Valley’s groundwater, part of an innovative inventory of the county’s groundwater situation, was released on July 9, 2013. It found a clear and localized decline in groundwater levels, and estimated groundwater storage decline of between 680 to 1,420 acre-feet per year since 1975. It also found salt water intruding into the southern parts of the area’s groundwater, as far up as El Verano.
Jasperse noted that the El Verano area and the southeast part of the City of Sonoma are both at sea level elevation, putting the groundwater in those areas effectively below sea level. Well monitoring shows that deep wells are declining by up to three feet a year in El Verano and up to five feet a year in the southeast part of the City.
A look at Sonoma Valley water use in 2012 shows that 59 percent came from groundwater, 26 percent was imported from the Russian River, 8 percent was local surface water, and 7 percent was recycled water.
The groundwater use varies greatly by the area it’s taken from, but on the whole, agriculture took 53 percent of the groundwater, with rural users taking 27 percent. The rest is broken up into roughly 3 to 7 percent each for irrigated turf, municipal, small water systems, and mutual/private water companies.
Locally, Kenwood (in the flatlands) uses about 1,300 acre feet of water, evenly divided between ag and residential. Glen Ellen, on the other hand, has access to Valley of the Moon Water and uses far less groundwater at about 350 acre feet a year. The entire stretch of Mayacamas mountains to the City of Sonoma accounts for 1,600 acre feet of groundwater every year.
Jaspers said the county is working out a four prong push to manage water that includes conservation, using recycled water, banking Russian River water (should any extra come our way), and capturing storm water runoff in the event we get more storms.
Recycled water may eventually be pumped directly underground to replenish groundwater supplies. Farmers have been using recycled water to irrigate crops since the early 1990s in Sonoma County, where available.
Jaspers also made it crystal clear that everybody would have to come to the table to work out solutions to any extended drought conditions. “Primary water users, including rural residential and agriculture, in groundwater depletion areas must participate in developing and funding solutions to address this problem.”
There have already been extended fights over rights to draw Russian River water for frost protection, and so far, agriculture has been slow to embrace the need to reveal how much water they are pumping out of the ground, much less any need to regulate that take.
Well monitoring is an essential part of the ongoing study of Sonoma Valley’s groundwater. Anyone willing to participate should get in touch with Kathy Pons, who has been a member of the Groundwater Study since the beginning in 2006 (833-2452). Tests can be monthly or twice a year and the results are completely confidential.
You can view Jasperse’s presentation to the SVCAC at www.scwa.ca.gov/files/SV_CAC_2014.pdf.