ALGICIDE POURED ON LAKE SHOULD REMOVE MUSTY TASTE.

Byline: Patricia Farrell Aidem Staff Writer

CASTAIC - A helicopter swept across Castaic Lake for hours Thursday, dumping chemical granules aimed at killing a pesky strain of seasonal algae that tainted much of Southern California's drinking water supply with a musty taste and odor.

By early afternoon, eight tons of copper sulfate had been spread on the upper lake, a reservoir serving not only the nearby Santa Clarita Valley, but water districts from Ventura County to Orange County.

``It's an effort to control green algae that grows near the surface,'' said John Bunce, operations superintendent for the state Department of Water Resources. ``The algae gets into the drinking water - it can give it a bad taste and odor.''

Neither the algae, called geosmin, nor the chemical used to kill it is harmful and the treatment is almost routine each summer, Bunce said.

To apply the algicide, crews affixed a huge spreader filled with copper sulfate to the underside of a helicopter. The exercise was monitored by water quality experts to ensure that the algae was killed with the minimal chemical use. The substance does not harm fish in the lake, Bunce added.

It could be Sunday before the earthy odor is gone from the water, which is being piped to an estimated 10 million people, Jill T. Wicke, water system operations manager for the Metropolitan Water District of Southern California, told City News Service. More customers than usual are receiving state water stored in Castaic Lake because an East Los Angeles county pipeline has been shut down for maintenance.

The impacts of the algae growth will vary from region to region, as local water agencies blend various water sources.

CAPTION(S):

photo

Photo:

(color) A helicopter carrying a spreader filled with copper sulfate - an algicide - passes over the upper Castaic Lake on Friday.

David Crane/Staff Photographer