Sonoma Creek is drying up
Stewardship by creekside property owners is needed now more than ever if young steelhead are to survive the summer of 2021
By Steven Lee
Have you seen the creeks lately? They are about as dry as they’ve ever been, at least in the memory of this Sonoma Valley native. After a very good rain year in 2019 (67.5 inches here in Glen Ellen by the Sonoma Developmental Center), and an average annual rainfall of ~35 inches, we had just 24.9 inches in 2020, and a scant 14.0 inches thus far in 2021.
Last year the seasonal creeks stopped running early, by June or so, and this year we never even saw flow at all in most seasonal creeks. Here at the Sonoma Ecology Center, we’ve been measuring streamflow around the valley since 2015, with extra resolution since 2017 in the steelhead-critical upper Sonoma Creek section between Eldridge and Kenwood. This summer, Sonoma Creek started off the dry season with lower streamflow than was measured at the end of dry season 2020 (less than 1 cubic foot of water per second)! Toward the end of last summer Sonoma Creek stopped flowing completely in the vicinity of Watmaugh Road. This year by mid-August it had already dried to a series of isolated pools all the way up to at least Agua Caliente Road, with just a trickle of flow occurring through Glen Ellen to around Sonoma Mountain Road, where the perennially flowing Graham Creek connects in.
Inflowing groundwater in that section, from Graham Creek to Kenwood, is what sustains dry season streamflow in the rest of Sonoma Creek, and is the reason we continue to have steelhead in this watershed. Young steelhead must endure two or more summers in the creek before migrating to the ocean. Good flow and cool, deep pools are critical to their survival.
The importance of this section of the creek is the reason we began our Sonoma Creek Streamflow Stewardship Program back in 2016 with a grant from California’s Wildlife Conservation Board (WCB). The purpose of this program was to study streamflow patterns in the creek and to work cooperatively with any landowners still pumping creek water to help them find alternative solutions for their irrigation needs (yes, this remains conditionally legal, but is discouraged). No one is pumping huge volumes of water from Sonoma Creek, but many smaller diversions remain present in this wetted section for irrigating lawns and garden beds, and these collectively impact dry season streamflow, especially in a year like this, when the creek is drying to a trickle.
In most years the problem isn’t a lack of ample water in the watershed overall, it’s just coming all at once in very flashy storm events and racing down the creek channels instead of soaking into the ground and recharging aquifers. Thus, with less water to seep back out of the ground later, streamflow is not lasting as long into the summer as it should. If one is to rely on the creek for their water needs, better to pump and store water in the winter or spring when it is plentiful than to do it late in the dry season when the steelhead need it most to survive.
Better yet is to employ a rainwater harvesting approach which eliminates the need for creek pumping altogether. This is the approach I’ve taken at my own property, and I filled my ~60,000-gallon system this year even with the scant rain we received! As part of our program, two such users of stream water agreed to follow this stewardship approach and signed letters of support for a subsequent WCB grant, recently awarded to the Sonoma Ecology Center. The grant includes funding to help two or more landowners develop water storage strategies, making dry season stream diversions unnecessary. One of those landowners ended up following my lead and is instead pursuing a rainwater harvesting system for their irrigation needs. Two additional landowners have signed on to plan for larger scale water storage and infiltration projects on their properties.
Yet another landowner, Mark Brewer, stopped pulling water from the creek altogether this year. After seeing dramatic changes in streamflow over the past few years, Brewer had already sharply decreased his use of creek water in the dry seasons. He feels so strongly about this that he has been willing to take a lead role in encouraging others to follow suit.
To be clear, this isn’t about demonizing certain landowners’ choices and actions. In fact, we all have a hand in this water story, from those of us who rely on spring water sources to those who draw from wells, including streamside wells, that are basically pumping the same water that feeds the creek, but also the deeper wells which support, among other things, production of the wines we all love to drink.
This is about finding solutions — solutions that help people improve their water security but also help the environment in the process. Stewardship actions like this can help turn things around and start to improve dry season stream flows… maybe not this year, but in future drought years. It is very possible that Sonoma Creek dries up completely this year. There is a reason we all bought properties along the creek. It wasn’t to look down upon a dry streambed!
If you are one of those folks still relying on the creek who might benefit from assistance in planning for a water tank installation, or if you’re interested in rainwater harvesting and/or other alternative water storage strategies, please call me at (707) 996-0712 or email me at [email protected]aecologycenter. org.
For more information about the Sonoma Ecology Center or to donate, please visit www.sonomaecologycenter. org/donate.
Steven Lee is an aquatic ecologist with nearly 30 years of experience in marine and freshwater research and monitoring. He grew up in the Sonoma Valley, swimming and playing in the same creeks and hills he now studies at the Sonoma Ecology Center, where he is the senior scientist and research program manager.