Arundo donax (Giant Reed) is a noxious weed that can infest and dominate watersheds including the Santa Clara River watershed (SCRW). Surveys completed by the California Invasive Plant Council found that the SCRW is one of the top three in terms of abundance and extent of invasive Arundo. Arundo grows incredibly fast and creates large dense stands that create many problems for the ecosystem and wildlife in the area. Native vegetation, like willows, have a hard time competing against Arundo, lessening biodiversity, habitat for fish and frogs, and inhibiting the natural flow of the river. Much of the adjacent land to the Santa Clara River is used for agriculture, which is a significant economic driver for Ventura County. Additionally, many municipal areas along the river are expanding, increasing the population that lives on the wildland urban interface. A. donax not only creates a huge fire hazard to the ecosystem and surrounding communities, but it also consumes much more water than native species, almost four times the amount.
The Ventura County Resource Conservation District (VCRCD), in partnership with Channel Islands Restoration (CIR), implemented 1 year of Arundo donax initial treatment in the Santa Clara River just below the Freeman Diversion. With a grant from State Coastal Conservancy and funding through Proposition 1, the project focused on treating and removing Arundo donax on a 9-acre parcel along the river. The project site has approximately 50% coverage of giant reed in native willow habitat (e.g., Salix exigua, S. lasiolepis, S. laeviogata). The goal of the Project was to remove 5 of those 9 acres using the “cut and daub” method, which consists of hand crews cutting the tall stalk at the base and painting the short stem with an aquatic safe herbicide. With regulatory and biological oversight by VCRCD, CIR successfully treated nearly 3.5 acres of Arundo. This project will rely on a passive restoration method now that this area of the river has been cleared of Arundo. Passive restoration allows the native vegetation that is already there establish and spread on its own rather than actively planting or staking the bank with locally grown plants from a nursery. Natural recruitment tends to yield stronger and more resilient plants.
Freeman Diversion
The Ventura County Resource Conservation District is working with many partners in both the Santa Clara River Watershed and Ventura River Watershed to create, conduct and work through plans to remove invasive species and restore the habitat in the entirety of these watersheds. There has been great progress and much still to accomplish but with funding from state agencies, like State Coastal Conservancy, support from conservation partners and engagement from the community, the problems start to get a little smaller each year.
