Clear Lake Community Puts Strategies in Place to Recover from Harmful Algal Blooms in the Water Supply

In October 2022, a study led by the Public Health Institute revealed that microcystin, a toxin produced by cyanobacteria, contaminated private drinking water that many community members rely on in Clear Lake, California. The study was a collaborative project between Gina Solomon with the Public Health Institute, PHI’s Tracking California, Big Valley Band of Pomo Indians, and the California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) and State Water Resources Control Board’s Division of Drinking Water. The Climate Health Adaptation and Resilience Mobilizing (CHARM) project was developed shortly after in 2023 and led by PHI and community partners. CHARM aims to establish the first countywide and coordinated action plan for addressing the impact of extreme heat events and harmful algal blooms in Lake County.

“Jesus Campanero Jr. was a teenager when he noticed there was something in the water. He once found a rash all over his body after a swim in nearby Clear Lake, the largest freshwater lake in California. During summertime, an unbearable smell would waft through the air.

Then, in 2017, came the headlines, after hundreds of fish washed up dead on the shore. “That’s when it really started to click in my head that there’s a real issue here,” says Campanero, now a tribal council member for the Robinson Rancheria Band of Pomo Indians of California, whose ancestors have called the lake home for thousands of years.

The culprit? Harmful algal blooms (HABs). Often marked by unsightly layers of blue-green scum, these blooms happen when certain algae or microbes called cyanobacteria grow out of control, fueled by warm temperatures and phosphorus- and nitrogen-rich pollution.

The impact of harmful algal blooms ranges from disruptive to deadly. Some species of cyanobacteria release toxins, including one called microcystin that can damage the liver. Contact exposure can lead to symptoms like Campanero’s rash as well as headaches, eye irritation, wheezing and more. In recent years, HAB advisories warning residents not to drink their tap water have appeared in cities across the nation; 18 dogs in California died from suspected exposure to HAB-polluted waters in 2017.

The US National Office for Harmful Algal Blooms estimates that the blooms cost the nation upwards of $50 million annually in costs related to health, fisheries, recreation, tourism and monitoring. A 2017 survey of nearly 1,200 US lakes revealed that about a third of the lakes contained cyanobacterial toxins. And that number is growing.

“There’s no question that, in the freshwater field, there’s more of these events happening, more people being affected, in some cases more significant events,” says Donald Anderson, director of the national HAB office in Woods Hole, Massachusetts.

The ecosystems suffer as well: As the algae in blooms decompose, they deplete the waters of dissolved oxygen, causing fish to suffocate. But perhaps counterintuitively, in the case of Clear Lake, removing one specific species of fish may be a key tool for rehabilitation. Along with other efforts, an audacious plan is now underway to remove invasive carp, which kick up phosphorous in the lake, feeding the blooms.

Threats to water and to traditions

The Clear Lake watershed has sustained Native peoples for millennia. Campanero recalls stories from his elders of the lake teeming with wildlife from birds to bears to fish, including a revered minnow, the Clear Lake hitch.

But for more than a century, the lake has endured many assaults: Runoff has leached into the water from an abandoned open-pit mercury mine, now a Superfund site; runoff also comes from gravel mines, unchecked septic systems, cannabis farms and vineyards. Hitch are now on the brink of species extinction.

Local tribes had asked California’s Lake County to monitor the water quality but county officials said they didn’t have the capacity, says Sarah Ryan, environmental director for the Big Valley Band of Pomo Indians. So in 2014, after a bad bloom, Ryan and Karola Kennedy, then environmental director of the Elem Indian Colony of Pomo Indians, began their own water testing program.

The team focused on sampling water from areas often used for traditional tribal activities and ceremonies, uses of water that are not protected by maximum pollutant allowances stated in the 1972 Clean Water Act, Ryan says.

An early result found more than 17,000 micrograms of microcystins per liter in a water sample, dramatically higher than the 8 micrograms per liter cutoff recommended by the US Environmental Protection Agency for recreational water use, which includes swimming and fishing.

Sixty percent of Lake County gets its drinking water from the lake, and even before the monitoring started, people were sometimes afraid to drink their water, Ryan says. Big Valley’s monitoring program now provides regular updates to the community on Clear Lake’s water quality.

Monitoring hasn’t made the problem go away, though. A 2022 study published by the US Centers for Disease Control and Prevention, coauthored by Ryan, analyzed the tap water of homes drawing from the lake and found that 58 percent of them had microcystin levels at or above levels that require a drinking water health advisory from the EPA.

A team with a plan

Change may finally be coming. In 2017, a state assembly bill established a committee to set a plan in motion. The multimillion-dollar effort, which is ongoing, brings to the table representatives from the tribes as well as scientists and county officials.

Keeping nutrient-rich runoff from seeping into the lake would be an obvious step — for some lakes, it reduces the levels of nutrients fueling the blooms. But it is very difficult to implement and enforce such measures, at Clear Lake or anywhere else, says Anderson, coauthor of an overview of HABs in the Annual Review of Marine Science. “It’s just an extraordinary challenge,” Anderson says. In any case, at Clear Lake, estimates suggest that most of the phosphorus driving the harmful algal blooms has already accumulated in the sediment.

Several of the committee’s proposals aim to tackle that preexisting phosphorus burden.”

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Originally published by Knowable Magazine