Arundo Donax Removal Begins Near Dam

Contractors hired for the Matilija Ecosystem Restoration Project use a crane to see above the prolific stands of arundo donax

By Nao Braverman
The tall canes that surround the Matilija Dam are ruthless survivors. Though the arundo donax, known as giant reed, grows tall and majestic, enduring the canyon’s driest seasons, it spreads quickly, crowding out native plants and strangling vegetation that once fed and sheltered numerous species of wildlife.
Currently contractors have begun removing the highly invasive weed from Matilija Canyon as part of the Matilija Ecosystem Restoration Project. Efforts to bring native habitat back to the canyon area have been slowly progressing for the past 10 years, and are finally making headway under the lead of the Ventura County Watershed Protection District partnered with the Army Corps of Engineers.
The long-awaited eco-system restoration involves removal of the 59-year-old dam, the largest dam elimination in American history. Though the dam removal is still slated for 2009, contractors are already getting rid of the arundo along Matilija Canyon in an effort to make way for endangered steelhead trout and other species expected to thrive in the area once the dam is removed.
The highly invasive weed was introduced to California in the 1820s for roofing material and erosion control. It is being removed from the dam area to make room for grading, allow for sediment excavation so the creek will flow after the dam is removed, and for overall improvement of the surrounding ecosystem, according to Pam Lindsey, watershed ecologist for the Ventura County Watershed Protection District.
With a $5 million grant from the State Water Resource Control board, the government agencies are getting started, and spraying the arundo with glyphosate.
The herbicide has been found in water supplies and may cause health problems if found in amounts greater than the health standards set by the United States Environmental Protection Agency, according to the agency web site.
Contractors will not be spraying over water in Matilija, and the chemical dissolves in a relatively short time if it does get in the soil because soil has microbes that digest it, said Lindsey.
The maximum contamination level goal for glyphosate has been set at 0.7 parts per million, and if the chemical did reach the water, it would be in much smaller amounts than the EPA’s maximum allowable levels, she said.
A recent study by researchers at the UC-Santa Barbara Marine Science Institute are currently looking into a natural arundo removal method involving non-native wasps. The tiny wasp species, tetramesa romana, can lay eggs in the stem of arundo plants, weakening the weeds and making them susceptible to fungus infestation and disease, according to Tom Dudley, a biologist at the institute researching for the study.
Though the tiny wasps, also found in the Mediterranean region, have recently been let loose at a study site where arundo grows along the Santa Clara River, they work much too slowly to be utilized for the Matilija Canyon project, said Dudley.
The wasps will be an important tool which can be used to prevent the spread of arundo in the future, said Lindsey.
Jeff Welch, a Matilija resident, suggested in a letter to the editor, using man power, rather than harmful chemicals to remove the cane, but Lindsey said that neither man power nor heavy equipment would be nearly as cost-effective as the herbicide.
About $1.5 million was used to complete wildlife surveys and map out more than 1,200 acres of arundo. The other $3.5 million is being used in the removal process.