A BOOM IN BLOOMS
Just before the July 4 holiday, a group of recreationists went to the Bridgeport Reservoir to escape the sweltering heat – only to break out in rashes soon thereafter, Louis Molina, Mono County’s environmental health director, announced recently.
Now, cautionary signs at the shoreline warn beachgoers not to enter the water. The group’s ailments were presumably caused by a toxin released by a surplus of algae in freshwater lakes, he said.
Cyanobacteria, also known as blue-green algae, are a typical element of freshwater ecosystems, according to the EPA. However, with excess heat and nutrients, the microbes multiply rapidly and produce cyanotoxins, which are harmful to humans, pets and wildlife.
Exposure to cyanotoxins can cause gastrointestinal illness and skin infections in people, said Raymond Ho, Managing Director at the California Poison Control Systems in San Francisco.
“If you happen to be swimming in [the contaminated water] or even swallowing it, it can be quite irritating,” he says. “It’s sort of like an allergic reaction; people get hives and itching.”
Dogs and children, who are smaller and tend to ingest more water while submerged in water, are more vulnerable to these toxins than adults, Molina said.
In September, 2019, the state passed a bill requiring the State Water Board to develop a program to monitor and alert Californians of blooms.
That program reported sightings of algal blooms in Grant Lake, June Lake, Gull Lake, Silver Lake, Diaz Lake and Millpond last week, though no advisory has been made yet to limit beach access for those locations.
The Marina and Hilton Bay areas of Crowley Lake have also habitually become inundated with algal blooms, Molina said.
“It happens pretty much every year,” he continued. “It’s just a matter of time until they identify the toxin level in those areas and then they’ll post those caution signs and maybe even go with high warning signs if we get high toxicity levels.”
The Sheet first reported on Crowley Lake’s harmful algal blooms in August 2021, just two years after the program was initially developed. The county strongly discouraged visitors from going in the water in any capacity after a person allegedly died from ingesting the contaminated water.
There are varying degrees of danger posed by cyanotoxins.
On one end of the spectrum, the county may advise swimmers to use their judgment and avoid suspicious water. On the opposite side, they may restrict all swimming, fishing and boating.
When sampling, scientists either scoop a water sample from clumps of algae in the water or scrape a sample from the green mats atop rocks, said Carly Nilson, Senior Environmental Scientist at the Surface Water Ambient Monitoring Program.
Then they test to see what type of algae the sample is, whether it has produced toxins and the quantity of toxins.
Mammoth Lakes Tourism has not yet made changes or issued advisories in conjunction with their marketing but intends to monitor the situation, Executive Director John Urdi said.
“At this point we have not heard or seen any effect on visitation and imagine we won’t move forward unless something happens to shine an even brighter light on it,” he stated in an email. “I think people visiting may see it as an inconvenience”
The state does not have a long enough data record to assess whether the contamination has trended worse over the years because the program is so new, Nilson said.
Lots of things can affect the temperature or nutrient load of a lake, and consequently, it’s susceptibility to algal blooms, she said. If a lake is proximate to cattle, for example, phosphorus and nitrogen from cow waste can trickle into the water source and fuel the blooms.
Alpine lakes, often more remote and colder than lower altitude lakes, might be more protected from these environmental factors, she said. But even they have some evidence of toxic contamination.
The monitoring effort is reliant on both science and community partnership to develop an understanding of how these blooms may affect public health, said Nilson.
“The public really are our eyes and ears to kind of pinpoint where we should be focusing our energy,” she said.
People can submit photos of potential algae blooms to the Surface Water Ambient Monitoring Program to identify potential problem sites, she said. Community groups such as Friends of June lake also help crowdsource information.
