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Toxic algae blooms pinned on legacy pollutants: Cleaning up Pinto Lake...

Donna Jones, Santa Cruz Sentinel

Toxic algae blooms pinned on legacy pollutants: Cleaning up Pinto Lake described as daunting task

WATSONVILLE Cleaning up pollutants that cause toxic algae blooms in Pinto Lake will be a daunting task at best, a researcher said Monday.
The poison produced by the algae can cause rashes and intestinal upset and has been linked to sea otter deaths.
Findings from a two-year study of the blue-green algae or cyanbacteria that has long plagued the 80-acre lake in rural South County will be presented at 6 p.m. Tuesday at Padres Hall, 35 Browns Valley Road, Corralitos.
Marc Los Huertos, associate professor of science and environmental policy at CSU Monterey Bay, said runoff from farms contributes to the problem but pales in comparison to nitrogen- and phosphorous-laden sediments deposited in the lake 50 to 100 years ago. The nutrients, which may have come from hillsides eroded after clear-cutting of forests decades ago, are aided by favorable conditions.
It's shallow lake with lots of sun, Los Huertos said. It's really hard to control.
Researchers recently built a small treatment plant with the aim of reducing or removing toxins before they flow into Corralitos Creek and out to the Monterey Bay. It's too early to tell if the pilot project is a success, Los Huertos said.
Another idea, he said, if funding becomes available, is to seal the sediment with alum, a binding agent.
Los Huertos said cyanbacteria is one of the earth's oldest organisms, responsible for producing the oxygen that made our own evolution possible. It's found in lakes and freshwater bodies throughout the world, including the Klamath River system and several Southern California lakes, Los Huertos said. He added Pinto Lake is a particularly pernicious example.
The state requires warnings to be posted whenever toxin levels exceed 5 parts per billion. Robert Ketley, Watsonville's water quality specialist, said he typically posts warnings at the city park at Pinto Lake spring through fall, though currently levels have been running 3-4 parts per billion.
Right now it's probably a function of a cool spring and the late onset of summer, Ketley said, adding he's kept up warnings posted earlier this year because he expects the numbers to climb again.
In 2009, samples averaged 183 parts per billion. One oft-cited 2007 sample exceeded 2 million parts per billion, though Los Huertos called it very biased, saying it was taken from area with a high concentration of algae and not representative of the lake as a whole.
Los Huertos said people shouldn't panic.
It's like a lot of environmental issues, he said. It took a long time to develop, and it's probably going to take a long time to solve. It doesn't mean you can't go to Pinto Lake. More people should go to Pinto Lake to see what the lake is doing. It's a beautiful place.
Follow Sentinel reporter Donna Jones on Twitter: @DonnaJonesSCS

Pinto Lake Pollution
WHAT: Public meeting to discuss findings of research into toxic algae looms
WHEN: 6-8 p.m. Tuesday
WHERE: Padres Hall, 35 Browns Valley Road, Corralitos
DETAILS: 464-2950 or

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