By Chris Gralapp
Board member, BVCA
Some years ago, a neighbor of ours was conducting well monitoring, checking our wells a couple of times per year to gauge the static water levels in an effort to discern a seasonal or annual pattern. As the data accumulated, it was informative to see how our well levels were moving up and down. That limited little program was suspended, but a group of us in BVCA would like to revive the project, and expand it to include a broader reach of well samples in all parts of the Valley. This would be a monitoring project, and is unrelated to well metering, which is a program under discussion in Sonoma Valley and Santa Rosa Plain. To be clear, Bennett Valley is not slated for well metering at this time.
The aquifers under Bennett Valley are like a 3D puzzle—there is fracturing, folding and multidimensional pockets that seem to appear and disappear capriciously. The nearby Rogers Creek fault influences ground shifting, and for some of us, the blue clay that forms the floor of the valley can move and cause problems with our wells. It is important for us to understand our groundwater situation, and manage our wells responsibly, whether we be residential or agricultural.
A good case in point are the wells dotted around Batesole Drive, smack in the middle of the Valley. Even though these wells are in close proximity to Matanzas Creek, the water table has fluctuated significantly in the last decade. More than half of the wells on the street have felt the effects. Several have been re-drilled, my own being one of them.
My well went dry in 2010. Originally drilled at ~150 feet in 1959, it served us adequately for fifty years, then suddenly could no longer recharge. I was forced to redrill, and went down to ~1000 feet before a reliable water source could be discovered.
This experience sparked an interest in the vagaries of water in Bennett Valley—if it could happen to me and my neighbors, it could happen to others. In my research on the groundwater availability for Bennett Valley, I discovered that the county has identified a classification system:
Class 1 = Major Groundwater Basins—Santa Rosa Plain, Sonoma Valley and Petaluma Valley
Class 2 = Major Natural Recharge Areas—primarily West County around Sebastopol / Valley Ford
Class 3 = Marginal Groundwater Area—Bennett Valley /Warm Springs / others
Class 4 = Highly Variable Water Yield Area—NW Sonoma County to the coast, both sides of 101
On Sunday February 19, a group of us assembled for a well monitoring session conducted by David Noren, who grew up in BV and works as an environmental consultant. He has successfully set up a monitoring project in the Sebastopol area, and has agreed to mentor us to do similarly here. David expertly demonstrated the simplicity of finding the level of our wells. Three wells were measured, using three different devices each time, with surprising results—two wells were at 57 feet, and a nearby well was at 166 feet. The data are already interesting!
The goal will be to involve well owners from around the Valley to participate in the measuring and add to the dataset, so we can gain a clearer picture of the changes in our aquifer over time, and send data to Sonoma Water, to help them fill in their data gaps for our area.
David has agreed to conduct a larger scale demo at the Grange in April or May, inviting all interested neighbors to learn how to monitor their wells, and hopefully to sign on to be a part of the project. BVCA and Grange would like to jointly start a small capital campaign to purchase a sounding device, that can be used twice yearly for this project. Citizen science at its best!
Link: Sonoma County Groundwater Availability Map: Groundwater Map