LAKE COUNTY, Calif. – If at some point over the past month you've witnessed some unusual vessels working on portions of Clear Lake, you're seeing part of this summer's effort to address the proliferation of lake weeds.
With summer in Lake County comes an increase in lake weeds and algae, and since 2011 the county government has allocated more money to the work of keeping weeds out of popular swimming and boating areas.
Scott De Leon, the county's Water Resources and Public Works director, said the Board of Supervisors set aside $350,000 for weed abatement this year.
“This is a continuation of the weed program that we've run the last three years,” said De Leon.
Altogether, about 220 acres of the lake will be targeted for special treatment this summer, he said.
De Leon said the weed control work was divided into zones, with the county hiring two contractors – Martinez-based Aquatic Environments and Pestmaster, based in Lake County and specializing in herbicide treatments – at a total contract cost of $274,340.
He said that leaves the county with some funds left over in case followup weed treatments are needed later in the summer, as once the weeds are pulled other types usually comes up to replace them.
Conditions are “absolutely” improving following treatments, De Leon said.
Five weed harvesters owned by Aquatic Environments worked off Library Park and along the Lakeport shoreline in June.
They began around the middle of June, said De Leon. “They were assigned about 135 acres of area to treat along the western edge of the upper arm here, all along the Lakeport shoreline.”
The weeds, once harvested, are taken Lake County Waste Solutions and put into the greenwaste, De Leon said.
De Leon said they are creating boat lanes leading to boat ramps, commercial areas and high density residential areas along the lakeshore. There also is a shoreline lane about 50 feet wide just on the outside edges of piers and docks, and the harvesters worked the entire area off Library Park from First through Fifth streets.
In addition, they were treating a recreational area along the Lakeport shoreline where Lakeshore Boulevard meets the lake, stretching down to Alterra. De Leon said the area has historically been very popular for water skiing because it's protected from the wind by trees and topography.
Aquatic Environments specializes in mechanical harvesting, but there are areas within that treatment zone where spraying is used instead due to the presence of hydrilla, according to De Leon.
De Leon said the state doesn't allow mechanical harvesting within a quarter mile of a hydrilla location.
The non-native hydrilla is described by the California Department of Food and Agriculture as a “pernicious aquatic plant which infests natural and man-made aquatic ecosystems.” It was first found in California in 1976 and has posed a problem on Clear Lake for the past few decades.
Lake is one of nine California counties where CDFA conducts eradication efforts; the agency said the largest eradication effort, beginning in 1994, was on Clear Lake's infestation.
CDFA's 2012 hydrilla report said plant numbers remained low last year, at 26 plants in five locations, but that was an increase over the six plants found in 2011.
Besides hydrilla, there are many different lake weeds of concern. Sago pondweed was the main weed pulled up by the mechanical harvesters over the past month, as it tends to be the first weed to sprout early in summer, De Leon explained.
As the summer progresses, other varieties sprout, including curly-leaf pondweed, De Leon said.
After the initial treatment, if other weeds come up, a followup treatment could occur, he said.
The lake's weeds came up earlier this year than last, he said.
“A lot of the areas that we're treated were topped out,” which De Leon explained meant that the weeds already had reached the water surface and were spreading out over it.
“We are seeing an abundance of weeds due to clear conditions,” said De Leon, noting that the weeds also are extending much further out into the lake than has been seen in the past.
The lake is shallow due to lack of rain, and those shallow conditions seem to be contributing to the weed profusion, as De Leon said sunlight is more easily able to reach the bottom of the lake, with that sunlight encouraging weed growth.
The recent hot conditions also kick-started algae, which started growing once the water temperatures climbed, he said.
“We have received quite a few phone calls about the algae,” he said. “But it is a natural phenomenon that we really can't control.”
He said wind and cooler temperatures help knock down and break up the algae.
For more about the county's aquatic weed management visit http://www.co.lake.ca.us/Government/Directory/Water_Resources/Aquatic_Plant_Management.htm .
Email Elizabeth Larson at This email address is being protected from spambots. You need JavaScript enabled to view it. . Follow her on Twitter, @ERLarson, or Lake County News, @LakeCoNews.