Plans to control weed fall short

By BOB NORBERG
THE PRESS DEMOCRAT
Saturday, July 14, 2007

A $2.1 million, three-year program to control a weed choking the Laguna de Santa Rosa has made headway but is falling short of expectations, officials said.

"To say it is worse is untrue, to say it is solved is untrue," said Julian Meisler, restoration manager for the Laguna de Santa Rosa Foundation. "We have a long way to go."

As a sign of success, Meisler points to the return of otters and osprey to the laguna and recreational use by kayaks and canoes in areas once choked by the weed, Ludwigia, which grew to be 5 feet tall.

"You couldn't get in there with a canoe in the summertime; it was a solid wall of plant," Meisler said. "The coverage was so great that using it for fishing by osprey was not a possibility."

In the channels near Rohnert Park, however, Ludwigia returned this spring with a vengeance, looking almost as bad as it did two years ago, though Sonoma County Water Agency officials say it was only a foot tall, not four, and not as dense.

"It came back, although not nearly the way it was," said Keenan Foster, the agency's senior environmental specialist.

After this year, funding for the control program runs out and there are no plans to spray, harvest or take any other measures to combat the plant.

It could mean that within five years, the Ludwigia will be just as bad as it was before the program started.

"Doing nothing is not an option," Meisler said. However, "we don't have the money, not even the money for a plan yet."

There are two native Ludwigia species in the laguna and along the Russian River, but since those two species evolved in the ecosystem, there are natural checks and balances that limit growth.

The non-native species being targeted was first seen 30 years ago, but took off in the past decade, choking out the native water plantain, swamp knotweed and marsh pennywort and various rushes, sedges and grasses.

The laguna has provided an ideal place for the plant to grow, with shallow, warm, stagnant and nutrient-rich water, and the non-native species now accounts for 90 percent of the Ludwigia found there.

In 2004, the Ludwigia Task Force was formed and a plan developed to check its growth.

"It wasn't an eradication project, it was to try to bring the plant down to a minor rather than a dominant member of the plant community," Meisler said. "It is still a dominant member, but that density is reduced and we have learned a lot in the process."

The $2.1 million program is in its third and final year, funded by the Sonoma County Water Agency, city of Santa Rosa, Marin/Sonoma Mosquito & Vector Control District, and the California Wildlife Conservation Board.

It involves spraying herbicides and mechanically harvesting the plant on 130 acres of the laguna. In the first two years, 21,000 cubic yards were trucked away and this summer workers are expected to haul out another 5,000 cubic yards, which would almost cover a football field three feet deep.

The Ludwigia effort is separate from the ongoing program to remove eight acres of pepper weed from the laguna near Sebastopol.

Faced with opposition to spraying, an effort was mounted to pull the plants by hand. Because that didn't succeed in killing the deeply rooted plants, Meisler said, the pepper weed will be sprayed and covered with tarps.

As a measure of success against Ludwigia, Meisler said 12 percent of the sample plots the foundation monitors are choked with the plant, compared to 79 percent when they started.

The removal and spraying also open up waterways so mosquito control officers can get in to spray for mosquito larvae.

Meisler said there is no support for the continual spraying and harvesting, which is expensive.

He said the long-term solution will include planting trees and shrubs on the banks. The foundation put in 2,100 trees and shrubs along a two-mile stretch of the laguna this spring, using a separate $500,000 grant.

Meisler said other measures could include deepening channels and removing sediment, and the foundation is looking for a grant to monitor nutrients from such places as lawns and golf courses.

You can reach Staff Writer Bob Norberg at 521-5206 or bob.norberg@pressdemocrat.com

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