* Editor’s note: This is the last in a three-part series of articles by the Putah Creek Council to educate residents about a creek restoration project to improve water quality and wildlife habitat in and along Putah Creek.
In 2010, Putah Creek Streamkeeper Rich Marovich, applied for and was awarded funding for the “Pleasants Creek Sediment Reduction Project” from Proposition 50 water bonds through the State Water Resources Control Board to address erosion coming from Pleasants Creek, a tributary to Putah Creek.
The work intends to stabilize eroding stream banks that deliver so much sediment downstream during rain storms that it threatens the reliability of one of Solano County’s drinking water sources: Putah Creek.
Unprecedented erosion along Pleasants Creek began shortly after the completion of Monticello Dam on Putah Creek. The dam creates Lake Berryessa, a major source of drinking and irrigation water for Solano County during the summer.
During rain storms, Pleasants Creek swells in size, sending thousands of gallons of water per second into Putah Creek. However, Monticello Dam retains the water that naturally would have flowed down Putah Creek, keeping Putah Creek fairly small even during storms.
Because the magnitude of storm flows on Putah Creek and its tributary Pleasants Creek are now unequal, Pleasants Creek enters Putah Creek at a steeper slope, creating essentially a mini-waterfall. Pleasants Creek began to down-cut and widen to disperse its energy, causing massive erosion.
Pleasants Creek and other tributaries downstream of Monticello Dam are now roughly three times deeper and wider than before the dam was constructed. More detail on this process is available at www.putahcreekcouncil.org/news.
Ranchers living along Pleasants Creek began to lose land to erosion at an alarming rate after the completion of Monticello Dam. They armed creek banks with an invasive plant, arundo (a false bamboo), in the hopes that it would curb the erosion and prevent their land from being washed away.
Within a decade, the opposite happened: Arundo had spread so aggressively that it sped up erosion.
“At the time, the federal government was promoting arundo as a cure-all for erosion,” Marovich said. “What they didn’t realize is that because arundo is not native to this area it does not behave favorably during storm flows. Our native streamside plants like willow lay flat during storm flows, allowing water to pass with little obstruction while their roots hold streambanks in place.
“Arundo does the opposite — it’s like having millions of cement pillars in a creek, each of which stands rigid during storms, sending raging water into unprotected banks and promoting streambank failure.”
Marovich is now at the helm of a three-year project to begin addressing the massive erosion in Pleasants Creek, the first step of which is to control arundo. Marovich’s team will work with willing landowners to survey high-priority sites, treat arundo and install native plants at places where arundo was removed.
The re-shaped banks will be armored by native plants, and the stream flow will be directed away from vulnerable banks using lines of boulders in the channel. The lines of boulders will be placed by trained stream engineers into structures that redirect the water’s energy away from eroding banks using a method called bio-engineering.
A pilot project at Ethel Hoskins’ ranch in 2002 stabilized an eroding bank with boulders and vegetation that withstood high flows in 2006 and 2008 without damage. The project created gently sloped floodplains along the flow channel where native vegetation now flourishes. The boulders have disappeared under thickets of willow, rushes, cattails and other native vegetation in what was previously a barren and vertical streambank.
Marovich went on to clarify that “None of the methods can be used in isolation. No quantity of boulders could stabilize the streambed unless we first control the arundo, slope back the banks in high-priority areas, and then use the boulders to direct the stream flow away from vulnerable banks. Moreover, the long-term success of this project hinges on establishing native plants in disturbed areas. Native plants’ roots will form a web of deep-reaching roots which will provide the strongest erosion protection possible.”
Native plants not only provide superior erosion control, they also provide habitat for wildlife.
“Our partnership has been monitoring wildlife at restoration sites along Putah Creek for about 15 years,” Marovich said. “Once native vegetation is restored to the landscape, native wildlife follows. We’re often amazed at how quickly birds move back into a restored area that was once dominated by impenetrable thickets of weeds.”
“I have my grandfather’s journals dating back to the mid-1800s, and he documented everything from farm yields to weather to wildlife,” she said. “We’re never going to see what he witnessed, but as I’ve watched wildlife return to my land over the past decade it’s been very gratifying to see that doing right by my land has brought back some of the richness my grandfather enjoyed.”
The project will continue through December 2014.
While no one anticipates rolling back the hands of time, project success will increase the reliability of water supplies downstream, reduce invasive weeds delivered to downstream locations, and increase wildlife habitat. Given the success of the similar pilot project at Hoskins’ ranch in 2002, the project team anticipates similar results for more Pleasants Creek landowners in the coming years, and helping Pleasants Creek — and landowners, wildlife and downstream water users — find more peace.
If you are interested in learning more about this project, visit http://tinyurl.com/solanowater.
When the rains return this fall, Putah Creek Council will organize groups of volunteers to help replant restored areas with native plants. If you’d like to hear about tree planting opportunities, sign up for Putah Creek Council’s e-newsletter on the home page at www.putahcreekcouncil.org.
Readers of this paper are invited to take a quiz about what they learned from this article. A winner will be drawn randomly from all entries, regardless of how many answers are correct, in October. The winner will get $100 cash. Deadlines and the quiz are available at http://tinyurl.com/creekquiz2.