Lake WMA – California Invasive Plant Council

Chair: Katherine VanDerWall, Lake County Agricultural Commissioner

General contact: Katherine VanDerWall, 707-263-0217, Katherine.Vanderwall@lakecountyca.gov

Mapping contact: None

Meetings: Once every two months at the Lake County Department of Agriculture Building in Lakeport; also online via Teams

Outreach Summary:

Annual Weed Tour in spring or early summer
2025 Weed Tour: May 8 – aquatic weeds at Clear Lake State Park – and May 9 – terrestrial weeds at McLaughlin Preserve
2026 Weed Tour: TBA
Presentations on weeds of Lake County are given as needed for local organizations like watershed groups.

For Invasive Weed Awareness Week, Lake WMA members go before the County Board of Supervisors to receive a proclamation paralleling the state legislature?s proclamation, an event that is aired on local television
Articles about the Lake County biocontrol program have appeared in a local paper and in a Farm Bureau publication.

GPS technology was used to survey and create GIS maps for arundo and tamarisk species over 70-75% of Lake County. Of the mapped area, 60% has been treated for arundo using two forms of chemical treatment. Most plants were originally treated using the cut-and-daub method, and then any re-growth was treated a second time by bending the plant down and spraying it with a dilute herbicide. Project partners included the East Lake and West Lake Resource Conservation Districts, Lake County Public Works, and the Agricultural Commissioner’s Office.

Broom species were grazed by goats on 1.5 acres at the Robinson Rancheria in Nice, on the northern end of Clear Lake. A follow-up treatment with clove oil on new shoots and re-growth during intense summer heat was very effective.