What's the green sheen on Big Bear Lake? What you need to know about harmful algal blooms

If you’re heading to Big Bear Lake to beat the heat — keep people and pets out of the water.

Officials have confirmed harmful algal blooms throughout the lake that are showing up as discolored water with a green sheen, scum and floating algae.

The blooms can produce potent toxins that could cause you and your furry friends to get sick.

Marisa Van Dyke, a senior environmental scientist with the State Water Resources Control Board, told LAist these conditions in California’s lakes and streams are primarily caused by tiny bacteria that grow into big, flower patch-like blooms.

“When you inadvertently swallow some of that water, it can contain those toxins,” she said. “It can be quite severe and cause you to need to have some hospitalization or even visit an animal veterinarian to get treatment."

What you need to know

People are being urged to avoid swimming, eating shellfish from the lake and drinking or cooking the water. Officials said boiling or filtering the water won't make it safe.

For anglers on the lake, Van Dyke recommends rinsing the fish off before handling and only eating the filets.

Dogs and children are especially vulnerable to exposure because they’re more likely to swallow water while playing and swimming, according to the State Water Resources Control Board.

Do not let pets in Big Bear Lake or near scum along the shore.

The harmful algal blooms in Big Bear Lake.

(

Courtesy State Water Resources Control Board

)

“If [the water] looks a little bit more green … and there's a little bit more growth of something that looks kind of like a plant but not quite, there might be a harmful algal bloom occurring,” Van Dyke said. “So keep an eye on children and pets so that they don't get in contact with that material.”

If you do have to dip your toes in, rinse yourself, your family and your furry friends with clean water after. Van Dyke also recommends drying off and changing into a pair of clothes as an extra precautionary measure.

You can learn more about healthy water habits here.

What to watch for

If you come into contact with harmful algal blooms and start showing symptoms such as eye irritation, rash, headache and vomiting — contact your doctor right away. It could also cause neurological effects, Van Dyke noted.

For dogs, the symptoms can include loss of energy and appetite, diarrhea, seizures and vomiting. You should reach out to a vet immediately if they start showing any signs.

People are asked to report any potentially related illness to state officials here.

Where is it safe to swim

Warning signs have been posted around Big Bear Lake, but when in doubt, stay out.

It’s prime time for harmful algal blooms in California. They’re most common between late May through October, although they can pop up year round, according to officials.

Van Dyke said research has shown that in the last decade, harmful algal blooms have been showing up more in lakes and reservoirs.

“There's many things that are driving that, including climate change,” she said. “So it's not just the warmer temperatures, but also less precipitation.”

California has a harmful algal bloom map that shows if any outbreaks have been reported in the area.