Toxic Muck: California’s Algae Problem Is Worse Than Ever

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Blue green algae at Discovery Bay.  (Lesley McClurg/KQED)

Algae blooms are a natural feature of summer, but the record levels of cyanobacteria, or blue-green algae, are rattling state officials this year.

“Everyone’s on edge,” says Bev Anderson, a scientist with California’s State Water Resources Control Board. “We are seeing more than we’ve ever seen before.”

She says her inbox overflows with reports of new algae sightings every morning. In some parts of the state, it looks like someone poured a giant can of green paint into the water. And the smell can be rank. When a bloom dies, it reeks of rotten eggs.

So far this summer, the state has posted warning signs at 30 freshwater lakes and reservoirs — advising boaters and swimmers to stay out of the water.

“We are getting blooms all over the place this summer," says Anderson. "We’ve got a massive bloom in Lake Elsinore, a lot of the East Bay Parks, Shasta Lake, Lake Oroville, Mountain Meadows Reservoir… and toxin levels are crazy.”


It's not just the number of outbreaks that's worrying. It's also the toxins blue-green algae can produce.

Health officials get nervous when they detect microcystin, one of several toxins produced by algae, at 20 micrograms per liter.  This year, they're detecting levels of 150,000 micrograms per liter.

The docks behind homes at Discovery Bay are quieter than usual due to fears of blue green algae toxins.
The docks behind homes at Discovery Bay are quieter than usual due to fears of blue green algae toxins. (Lesley McClurg/KQED)

But don’t worry — there have not been any reports of contaminated drinking water. Utility districts are screening for toxins to try and keep tap water safe. Plus, drinking water is usually drawn from levels far below where algal blooms tend to float in reservoirs.

Summer Recreation on Hold

Boaters and swimmers are the ones who are suffering.

Discovery Bay, a suburb east of Walnut Creek, is normally buzzing with boats and jet skis. But this year the waterfront has been eerily still for weeks. There isn’t a soul in the water.

Local resident Dave Holmes says he’s never seen anything like it. “We’ve been here since 2002. It is by far the worst we’ve ever seen," he says.

With disgust, Holmes watches his white speedboat and blue kayak bob in mucky green water behind his home.  

Kathy and Alfred Gulizia cringe from their table at the Boardwalk Grill. Slime wraps around docks at Discovery Bay's marina.

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“We’ll swim in our pool at the clubhouse where we live,” says Alfred Gulizia.

Wade Hensley regrets jumping in the water in mid-July. He ended up in the hospital because his body went numb from the waist down. His doctors can’t explain why he still can't feel his legs and feet a month later.

County health officials did find microcystin in Discovery Bay. Common symptoms are dizziness, rashes, fever and vomiting -- not numbness. But it can be lethal to dogs and livestock, since the animals are more likely to drink the water or lick the slime off their fur.

Twenty two states have had toxic algae outbreaks this summer. Florida declared a state of emergency in two counties, and a bloom sickened more than 100 swimmers in Utah in July. In 2014, 38 states and the District of Columbia reported harmful algal blooms in lakes or other freshwater bodies.

Rising Temperatures to Blame

Scientists blame a changing climate for the blooms — at least in part.

“We’re getting higher temperatures than we’ve seen ever in the past,” says Anderson. “California had an unprecedented drought for the last five years, which have the water levels very low in a lot of areas.”

Shallow waters allow the sun to penetrate easily, and bacteria thrives in hot water.

"We have created these massive bathtubs for them to be able to bloom in," says Anderson. "Tubs are nice and warm, and that’s what these organisms need."

Add fertilizer runoff from farms, golf courses and lawns to the cocktail — nitrogen and phosphorus are the main culprits. This year is especially bad, because Northern California’s wet winter washed an unusually high concentration of these and other nutrients into the water.

But toxic algae is not only showing up as a result of urban pollution. Scientists are starting to find blue-green algae in surprising places like pristine mountain lakes and alpine streams.

Scarce Solutions Forebode a Scary Future

Worst of all, scientists are just starting to understand a problem they expect to escalate.

“Some areas have been monitoring and seeing blooms for decades, but they’ve never had toxins,” says Anderson. “And when these massive blooms die off, they can cause a rapid drop in dissolved oxygen levels.”

Less oxygen can lead to massive fish die-offs, leaving an ecosystem completely altered. In 2010, a microcystin outbreak killed sea otters off the coast of Monterey Bay.

Scientists are scrambling for solutions. Algaecides can help temporarily, but the chemicals can also backfire by promoting other toxins.

Anderson’s advice is simple.

“If in doubt, stay out!” she says. “Don’t go in, don’t let your dogs in.”

There’s nothing to do now but wait for the green muck to disappear, and hope for a cold winter to kill it off.