Two beaches at Silverwood Lake in San Bernardino County remain closed by the state Department of Water Resources because of huge mats of blue-green algae known as cyanobacteria.
Swim areas in LA County’s Pyramid and Castaic lakes have also been put under advisory.
“These are warnings that should be taken seriously,” said Doug Carlson from DWR. “People who ingest it or accidentally swallow these algae can become sick. Pets can die from it”
While Silverwood Lake remained open to boating, the Sawpit and Cleghorn swim beaches were closed to swimming on Friday. Officials urged the public to avoid direct contact with visible algal blooms.
The recommendations are based on the potential health risks from blue-green algae. Water sampled in the Sawpit swim area contained approximately 6.1 micrograms of the toxin microcystin per liter, a concentration just above the “Warning” action level of 6.0.
Blue-green algae can pose health risks, particularly to children and pets. It can cause eye irritation, allergic skin rash, mouth ulcers, vomiting, diarrhea, and cold and flu-like symptoms. Pets can be especially susceptible because they tend to drink while in the water and lick their fur afterwards.
But USC biology professor David Caron said it’s easy to stay safe while cooling off in the lake this summer – just pay attention to where you’re splashing.
“If you see large aggregations of material, just don’t risk it,” he told KPCC.
The toxic algae blooming right now in pockets of Southern California form scums of blue-green, white, or brown foam at the water’s surface and accumulate along the shoreline and boat ramp areas. That’s a sign for swimmers to keep out.
“Don’t let your dog go swimming in there, don’t go in that material,” Caron said.
Caron studies both ocean and freshwater algae. He said there have been a rise in toxic algae warnings because of increased awareness of the issue in affected communities.
“We have a number of problems, and have had a number of problems for many years,” Caron said.
Algal blooms take place where there’s low circulation, agricultural runoff, warm water or a combination of all these.
Bloom conditions can change rapidly, and wind and waves may move or concentrate the bloom into different regions of the lake, officials said.
But Caron says the summer heat as well as lingering effects of the drought also ramps up freshwater algae production.
“As more evaporation takes place, as there’s less replenishment of water, some of these problems have been exacerbated by climatic conditions,” he said.
Enjoying the water worry-free this summer is simple: look at posted signs, don’t let pets drink the water, and avoid kicking up algae foam with your boat – you could breathe toxins in.
The Department of Water Resources recommends taking these extra precautions:
- Don’t wade or swim through algae blooms or mats.
- Don’t let pets drink algae-infested waters, and be sure to rinse them off with clean water to prevent algae lingering in fur.
- Don’t drink or wash dishes with untreated surface water from areas – boiling, purification tablets and camping filters don’t treat algae!
- Avoid eating fish, muscles and other shellfish from areas with algae.