The harmful effects of arundo (Arundo donax) and tamarisk (Tamarix) species are well documented. In fact, the California Department of Food and Agriculture (CDFA) recently proposed the addition of arundo and tamarisk, to the CDFA Noxious Weed List in the California Code of Regulations. The Ventura County Resource Conservation District, as lead agency for the Ventura County Arundo Task Force, in conjunction with its partners, proposed to undertake a regional arundo and tamarisk eradication program in the Upper Santa Clara River watershed. Invasive weed infestations are most effectively addressed on a regional scale and done systematically over a period of many years.

This project not only benefits the Upper Santa Clara River watershed, but also helps those restoration efforts downstream in Ventura County as it will reduce the amount of Arundo that annually washes out of the river channel and is deposited on downstream beaches. The long-term goal of the Ventura County Arundo Task Force is the eradication of Arundo from all portions of the Santa Clara River, both in Los Angeles and Ventura Counties.

The goal of this project was to establish an eradication program that demonstrates measurable riparian habitat improvements as the project progresses in the next twenty (20) years and beyond. The stated goals and objectives of the proposed eradication program are consistent with those of the Nonpoint Source (NPS) Program and the Watershed Management Initiative (WMI). Specifically, “Eradication of exotic species and habitat restoration” is listed as one of the priority projects on the Regional Water Quality Control Board’s (RWQCB) NPS Program’s Target Projects List. Also, in the WMI Chapter dated December 2000, the Regional Board lists “Impacts from exotic vegetation” as one of the significant watershed issues for the Santa Clara River watershed.

Removal of arundo and tamarisk increases the available surface and subsurface water that can be utilized for beneficial purposes. Water quality sampling will be done prior to eradication efforts and again after eradication has been completed. Short-term impacts of the removal project are also identified. Back to top.

The primary threats to the remaining riparian habitat of coastal southern California are invasive non-native plant species, including arundo and tamarisk. Arundo is a giant reed native to the Indian subcontinent and introduced by Spanish settlers to the western United States. Although historically useful for fencing, roofing, and fiber production, the benefits of Arundo do not outweigh its current negative impacts on local watersheds. Arundo has the capability to spread rapidly, forming large contiguous root masses covering several acres, effectively crowding out native riparian vegetation. This results in lower biodiversity of plant life, eliminating crucial habitat for birds, fish, and other wildlife that use riparian waterways.

Tamarisk is a native to south Eurasia and was introduced at the turn of the century for cultivation. It is an aggressive, woody invasive plant species that is relatively long-lived and can tolerate a wide range of environmental conditions once established. It can replace or displace native woody species, such as cottonwood, willow, and mesquite, which occupy similar habitats, especially when timing and amount of peak water discharge, salinity, temperature, and substrate texture have been altered by human activities. Stands of tamarisk generally have lower wildlife values compared to stands of native vegetation and have allelopathic effects by causing the surface soil to become highly saline, thus impeding future colonization by many native plant species.

Over time, arundo and tamarisk have spread rampantly throughout riparian forests in southern California. The Santa Clara River Watershed is no exception; arundo and tamarisk are present in the Santa Clara River and all its major tributaries, including San Francisquito Creek. Stakeholders in the watershed are anxious to see the arundo and tamarisk removed and have expressed interest in participating in the eradication efforts. Back to top.

This project has resulted in the development of the Upper Santa Clara Arundo River Watershed Removal Plan (SCARP). This plan includes a programmatic California Environmental Quality Act (CEQA) and National Environmental Policy Act (NEPA) document and related documentation for the implementation, maintenance, and monitoring of arundo and tamarisk removal projects within the riparian corridors (500-year floodplain) of the upper Santa Clara River watershed. The goal of this comprehensive document is to allow any agency or organization to perform arundo/tamarisk removal projects of any size within upper Santa Clara Watershed.

SCARP is a long-term eradication, monitoring, and maintenance plan, which takes into consideration: land ownership; degree of infestation; access; potential eradication methods and procedures; presence of threatened or endangered species; current work being done or planned/pre-existing environmental agency restrictions and permits; and funding mechanisms in place and/or strategy for funding further eradication in the Santa Clara River Watershed that may include Federal and State grants, Federal cost-share programs and in-lieu fee program potential. The programmatic environmental documentation will contain everything necessary to fast-track projects.

Vegetation mapping for the Upper Santa Clara River and its tributaries was also undertaken as a part of this project. Back to top.

Funding for this project has been provided in full or in part through an Agreement with the State Water Resources Control Board (SWRCB) pursuant to the Costa-Machado Water Act of 2000 (Proposition 13) and any amendments thereto for the implementation of California’s Nonpoint Source Pollution Control Program. Back to top.

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Maps and Related Information

Arundo Handout

Tamarisk Handout

Santa Clarita Site-Specific Implementation Project (Target Vegetation)

Santa Clarita Site-Specific Implementation Project (Vegetation)

SCARP Maps

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Documents

Final Environmental Impact Report (EIR)

Final Long Term Implementation Program (LTIP)

Site Specific Plan

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