Weeds invading Colusa Basin

Weeds are clogging up the Colusa Basin watershed.

"A lot of these species absorb a great deal of water and they can deteriorate the natural (landscape) and cause farmers and ranchers a great deal of problems," said Mary Fahey, watershed coordinator for the Colusa County Conservation Resource District.

Because the invasive weeds are not indigenous to the basin, which is comprised of most of Colusa County, as well as a fair chunk of Glenn and part of Yolo counties, they do not have a natural enemy to keep them in check.

Worst still, Fahey said, they are pushing out indigenous plant species at the same time.

"But there is really no comprehensive mapping of where they are," she said.

So Fahey, in developing an overall watershed management plan, is creating a GIS mapping of eight specific invasive weeds.

Those are Arundo, Tamarisk, Tree of Heaven, Barbed Goat Grass, Purple Starthistle, Yellow Starthistle, Perennial Pepperweed and Yellow Water Primrose.

Gene Massa, general manager of the Colusa Basin Drainage District headquartered in Willows, said developing a scope of the problem and mapping out the weeds is a good start.

"Basically the invasive weed that we deal with is Arundo," said Massa. "That grows in the valley and clogs passage of water through drains."

But it is not simply knowing where the weeds are.

For example, duck clubs and other property owners often purposefully plant Arundo, a reed- or bamboo-like weed, for soil erosion control, but by doing so, may cause flooding issues for neighbors.

Jean Miller, assistant agriculture commissioner in Glenn County, said it is not just the cost of fighting the weeds, but the cost to the crops' value.

"Tamarisk changes the salinity of soil," Miller said.

So even if a farmer is able to get rid of the weed, it could have already impacted the soil to the point of not being able to grow a crop there.

In turn, the farmer must spend a great deal more to get the soil back to a productive condition.

"Invasive species are a leading threat to biodiversity, second only to habitat destruction. And the economic cost is as significant as the ecological cost: in California, more than $85 million goes to fighting invasive plant and animals every year," according to the Northern California Conservation Center.

The center cites Cornell researchers that estimate the economic impact of invasive species, which includes bugs and other animals, to be $120 billion a year, or an average of $2.4 billion for each state.

"Given California's size and resources, the actual impact is likely greater in (California)," the center states.

The figures were not broken up to show the impact of invasive weeds alone.

"But it would be pretty significant," said Daniel Gluesenkamp, executive director of Calfora.org, an organization that collects information on virtually everything that grows in the state.

The group is particularly concerned with the impact invasive weeds have on natural habitat, but is involved in all areas of the research and data collection and sharing.

"They do the same thing out in the wild," Gluesenkamp said. "On the farm they are competing against crops; out in the wild they are competing against things that grow in the wild."

He said there are about 1,500 invasive plants in California.

"Of that number, most do not cause any harm at all, but there are others, about 100, that are the school yard bullies," Gluesenkamp said.

And because recreation and other outdoor industries represent equally significant economies in the state, invasive weeds are a holistic issue to address.

Fahey is looking for area residents to help her out by providing critical information about the location of the weeds.

The Colusa Basin Drainage District, along with the Glenn County Agriculture Department, the state Department of Fish & Game, the U.S. Fish & Wildlife Service, Yolo County RCD, Glenn County RCD, U.C. Cooperative Extension, the Maxwell Irrigation District and other organizations are part of the work effort.

"This project is the first comprehensive weed mapping effort in the watershed and will be a great resource for land managers in Colusa, Glenn and Yolo counties," Fahey wrote in an e-mail distributed to various agencies and individuals throughout the watershed.

Fahey, who works under a grant that goes through the end of June, has the basic mapping foundation done, and just needs to add the specific information about the weeds.

She hopes to have that done by the end of the calendar year.

"Then we will have to find funding for some kind of eradication plan," Fahey said.

Massa said the Glenn County Agriculture Department had some success with the Yellow Starthistle by bringing in a beetle that feeds on it.

"They had some success but (the beetles) didn't last long. They couldn't take the colder winters," Massa said.

Starthistle can dominate areas and dramatically hinder grazing.

And because the seeds can be carried from one area to another by the cattle, for example, it is very difficult to control.

Massa said whatever eradication plan is developed, it will have to be widespread.

"And it will have to be long-term," he said.