|SCWA will continue Cotati Creek Critters work in laguna
In 2005, the Sonoma County Water Agency (SCWA) supported the Cotati Creek Critters and the Laguna de Santa Rosa in their application for a grant from the California Department of Water Resources (DWR), with the goal of improving the Laguna de Santa Rosa.
Cotati Creek Critters, supported by SCWA and the City of Cotati, organized community workdays and worked together with a wide range of community partners to plant about 2,000 native trees and shrubs along a nearly one-mile stretch of the Laguna de Santa Rosa flood control channel between Liman Way and East Cotati Avenue in Cotati.
The project was nearly completed in May 2008, with a few tasks remaining – the removal of Himalayan blackberry and garbage and the installation of interpretive signs.
Over the last several years, CCC has organized volunteer community days to keep the channel free of trash and to slowly thin the successful native plantings to help prevent the channel from flooding during heavy rains.
Starting this summer, SCWA will take over the maintenance of this project as part of its ongoing Stream Maintenance Program (SMP).
The Water Agency’s vegetation management approach can be found in Chapter Five of the “Stream Maintenance Manual” at www.scwa.ca.gov.
Generally, SCWA’s philosophy is to take a “frequent but light” approach to vegetation management.
This approach gradually nudges habitat into the right locations over time, aesthetics are retained, and large disturbing changes are avoided unless sediment removal becomes necessary.
The work is done by SCWA maintenance crews, summer youth crews or supervised adult crews with an advising biologist onsite.
A primary goal of the SMP is to provide for flood capacity while retaining or developing habitat for plants and animals. This strategy is based on ecological “succession.”
Succession occurs after the land has been disturbed (by plant removal, bulldozing, floods or fires) and plant communities slowly transition from the species that are early colonizers – in creeks often young willows – to a more long-term composition and arrangement including mature willows, maple, ash and poplar.
To successfully design a restoration project using succession, we must overplant the early colonizers.
Currently, the existing density of plant species along the DWR project is higher than the designed target density for a flood channel of this size. This was a planned element of the overall project.
When SCWA performs its annual stream assessments, it will prioritize maintenance tasks at the DWR Project site. Some trees and shrubs will be thinned to provide capacity and habitat. Eventually, trees will be thinned so the trunks are separated by about 30 feet to 40 feet.
In the short term (one to three years), SCWA crews will focus on removing closely grouped willows, bushy vegetation inside the channel (red-stemmed dogwood) and removing lower limbs from the developing trees.
As time progresses, work will include greater spacing between retained trees with larger canopies, annual mowing of certain patches of vegetation, and wholesale removal of shrubby material below the top of bank as overall shading increases.
SCWA hopes to be able to continue CCC’s tradition of community days to replace and enhance plantings and to remove garbage.
In 2011, SCWA engaged the CCC and the Laguna Foundation to continue restoration work along a different section of the Laguna de Santa Rosa (Gravenstein Drive to Commerce Boulevard in Rohnert Park).
The maintenance of this newly restored section of the Laguna will be adopted by the Laguna de Santa Rosa Foundation, but SCWA hopes to continue to work in the future with volunteers to continue the community-building restoration work by the CCC.
Currently, SCWA holds four community events annually, geared to high school and middle school students. These days are planned by the Water Education Program and implemented in concert with the SMP goals.
Given community interest, SCWA would like to continue to partner with Cotati, Rohnert Park and community residents to restore creeks, clean up garbage debris, provide training opportunities for young people and further community involvement with local water resources.
Keenan Foster is a Senior Environmental Specialist currently working for the Sonoma County Water Agency in the Stream Maintenance Program. He has worked with SCWA for the past 12 years and as a professional biologist for more than 18 years. Specialty areas include plant taxonomy, terrestrial and riparian ecology, environmental management and regulatory permitting. Foster works closely with the Stream Maintenance Division to develop vegetation management and sediment removal standards that establish a balance between habitat function and flood control to reduce the cost and frequency of needed maintenance.