By Katy Hillenmeyer, THE PRESS DEMOCRAT
Article published - Jul 19, 2005
Herbicide spraying to control a fast-growing water weed began Monday in the Laguna de Santa Rosa, an unprecedented step to combat 10,000 tons of non-native Ludwigia clogging the waterway.
Working with two airboats and a tractor-like "swamp cat," aquatic weed control specialists from Martinez began surface-spraying glyphosate, a common herbicide chosen because regulators consider it among the least likely to contaminate ground water.
The spraying of about 130 acres between Occidental and Guerneville roads is expected to take up to 10 days and will be followed by mechanical removal of the invasive plants. It marks the first phase of a proposed $1.5 million, five-year project that calls for spraying at least once a year for three years under a plan to restore the wetlands system.
"With a problem of this magnitude, nobody could take care of it in a year, but we're hoping to see a continuous reduction each year," said Julian Meisler, restoration project manager for the Laguna Foundation, a nonprofit environmental group that is spearheading the spraying effort.
Ludwigia, the Uruguayan water primrose, has multiplied to cover 155 acres during the decade since landowners around the Laguna first began noticing its encroachment.
In addition to suffocating native plants, degrading the water and blocking the passage of spawning salmon, the densely packed Ludwigia provides cover for mosquitoes, thwarting efforts to control them and prevent the spread of West Nile virus. Sonoma County public health officials said seven dead birds and one horse have tested positive this year for the mosquito-borne virus, which can result in severe illness or death in humans.
The application of glyphosate, an ingredient in Roundup and Rodeo, is necessary to eradicate the stubborn weed, said Thomas McNabb of Clean Lakes, Inc., the Martinez firm that began spraying Monday under a one-year permit. Each fragment of Ludwigia can reroot and form a new plant, and researchers said the weed has the ability to double in size every 15 to 90 days in summer.
"Mechanically, we can harvest it, but if you don't do anything with the root, it's right back," McNabb said. "It's a waste of money."
But other environmentalists and members of the Sebastopol City Council continue to raise objections about herbicide use.
"I continue to hope that mechanical removal will be pursued before spraying to ensure that we take care of this problem in the Laguna without jeopardizing people's health," Sebastopol City Councilman Craig Litwin said Tuesday. "We don't want any outbreaks of West Nile, and we don't want any pesticide poisoning, so mechanical removal seems to be the most prudent choice."
Including the mechanical harvesting process, McNabb said, Clean Lakes, Inc., will continue its work through October.
The North Coast Regional Water Quality Control Board, which authorized Monday's spraying, also granted permission for spraying in flood control channels bordering Rohnert Park. Spraying there is expected to begin Thursday at the earliest, or next week.
The Sonoma County Board of Supervisors today will consider approval of a $500,000 agreement between the Sonoma County Water Agency and the Laguna Foundation to fund the foundation's Ludwigia management plan.
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