Invasive Vegetation Removal

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Yolo County Partners to Preserve Cache Creek Flood Capacity
By Beth Gabor, Yolo County Public Information Officer
November 9, 2006

Cache Creek Aerial ViewAnyone who has visited Cache Creek is aware of its scenic beauty from Clear Lake through Yolo County down to the Yolo Bypass. What you may not be as aware of is the extent to which non-native vegetation in the creek, such as tamarisk and arundo, threatens existing flood capacity in lower Cache Creek, contributes to bank and levee erosion, and degrades native riparian habitat. To address this issue, Yolo County partnered with the Cache Creek Conservancy this fall to remove non-native invasive plants in the section of the creek between I-5 and Road 94B.

Yolo County staff worked with the Conservancy and a geomorphologist to identify priority sites for vegetation removal based on their significance in maintaining flood capacity and reducing the rate of bank and levee erosion. Yolo County implemented the project as part of the Cache Creek Resource Management Plan with funding assistance from the Water Resources Association of Yolo County. The effort builds on previous efforts of the Cache Creek Conservancy, and more recently, the Yolo County Resource Conservation District to remove non-native vegetation in other sections of Cache Creek.

“The removal of tamarisk and arundo in lower Cache Creek will help to reduce erosion at key points in the flood protection system,” said Petrea Marchand, Yolo County Water Resource Coordinator. “Yolo County also plans to work with the Cache Creek Conservancy in the future to ensure that tamarisk and arundo do not come back.”

Non-native vegetation creates channel constrictions and deflects flows toward banks and levees – thus changing the course of the creek, and at times, contributing to levee failure. Removal of tamarisk and arundo will reduce this type of erosion, and also provide opportunities for the establishment of multi-tiered, native riparian canopy that provides much-needed wildlife habitat.

“It’s always been a priority of mine to improve Cache Creek’s flood capacity,” said Supervisor Duane Chamberlain. “Removing non-native vegetation is a step in the right direction.”

Yolo County is also working with the Water Resources Association, the City of Woodland, and the Yolo County Flood Control and Water Conservation District to evaluate possible solutions to provide residents in the vicinity of Cache Creek with flood protection beyond the creek’s existing capacity. The Water Resources Association most recently established the Cache Creek Flood Management Advisory Committee to review technical documents and provide recommendations for moving forward with this effort through a public process. They expect to establish a formal public process to seek input on flood management solutions in early 2007.

For more information on efforts to remove non-native vegetation on Cache Creek, contact Julia McIver, Yolo County Water Resources and Conservation Program Manager at (530) 406-4889.