Southern California

Algae Bloom Closes Diamond Valley Lake

Drinking water will not be affected by the bacteria, authorities say

Alex Vasquez

All recreational activities at Diamond Valley Lake have been suspended indefinitely due to a large bloom of blue-green algae at the bottom of the lake, the Metropolitan Water District of Southern California announced Thursday.

Boating, fishing and hiking are just some of the activities suspended around the lake until the district determines it is safe to use again. The algae, called cyanobacteria, sometimes releases harmful cyanotoxins into the water, which in high concentrations can be poisonous when ingested.

"We do know that this bloom is producing some of these cynotoxins, and so that's why we've taken this precautionary measure of temporarily closing the lake," said Paul Rochelle, microbiology unit manager.

Water quality experts, however, said local drinking water will not be impacted at all.

"This is a recreation issue, not a drinking water issue," said Mic Stewart,the Metropolitan Water District quality manager, in a news release. "We are not using [the lake] as a drinking water source right now. Even if we did, our processes for withdrawing the water from the lake and treating it will ensure its safety."

Metropolitan posted a signs at the lake last week telling visitors and their pets to stay away from the water due to the algae bloom, which looks like mats of green scum floating on the water.

Rochelle said he and his team will continue to monitor the situation and test bacterial levels daily. The district will lift suspensions "when conditions improve," which could take a week or more.

Rochelle expects the lake to reopen far before the end of summer, but cannot say exactly when due to the unpredictability of the natural phenomenon.

"It could be days, it could be weeks," Rochelle said. "In some extreme circumstances, blooms like these have lasted for a month or longer, but I don't expect that to be the case here."

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