CLEAR LAKE — The latest testing of the waters of Clear Lake by the Big Valley Band of Pomo Indians and the Elem Indian Colony found concerning levels of toxic cyanobacteria in six locations in the Lower Lake arm of the lake, as the County of Lake reported this week.
Cyanobacteria, also known as blue-green algae, is a naturally occurring bacteria that contains cyanotoxins, which are harmful in high concentrations to humans and animals.
Big Valley Pomo Environmental Director Sarah Ryan, who has been involved with the tribe’s methodical cyanobacteria testing program since its inception in 2014, said the current testing levels aren’t remarkably high, but are notable for their appearance all at once.
“We had higher toxin levels last year at the highest sites,” Ryan said, “but not all at the same time…This is the first time I remember a whole arm” of the lake being found with concerning levels of cyanotoxins “all at the same time.”
According to Lake County Public Health Officer Dr. Erin Gustafson, cyanotoxins can be harmful when animals and humans come into direct contact with them by skin contact or ingestion—with the potential for creating skin irritation, liver issues, gastrointestinal issues, nausea, vomiting, yellow skin and eyes, diarrhea and difficulty breathing, among other symptoms.
Asked about the airborne effects of cyanobacteria, Gustafson cited two recent studies—one from Florida Gulf Coast University and one from two Greek universities—that are aimed at learning more in that direction.
For now, she said, “we don’t have enough information” to know what the airborne effects are on humans.
While the current blooms in Clear Lake’s Lower Lake arm have caused the county to post signs warning against entering the lake near where concerning levels of cyanotoxins were found, Gustafson said it’s still safe to get in any parts of the lake outside of those areas.
The Big Valley and Elem tribes test biweekly at 30 sites around Clear Lake, and outside of the Lower Lake arm, no concerning levels of cyanotoxin have been found so far this year.
Elem Environmental Director Alix Tyler said that cyanobacteria are common in bodies of water, and their presence alone does not signify something is wrong.
“It doesn’t necessarily mean there is a huge problem with this lake,” Tyler said. “Cyanobacteria created photosynthesis and it gave us oxygen,” she added. “It’s one of the reasons we are living as human beings.”
Ryan said the two tribes combined spend roughly $150,000 to $200,000 annually on the advanced testing program, which includes looking at samples under microscopes, tracking results, documenting progress, and doing work in the field.
All told, she said, it’s “a lot of staff time.”
Funding comes from the California Environmental Protection Agency, the Bureau of Indian Affairs branch of Water Resources, and other entities that provide grants for the work.
While the concentrated levels of the bacteria sometimes found in Clear Lake are harmful, no illnesses in people have been confirmed as caused by cyanotoxins to date, said Gustafson. Potential cases have cropped up, she added, but no lab tests are available to easily determine whether cyanotoxins are the cause of a given health issue.
Along with the lake water, tap water sourced from Clear Lake is also being tested for cyanotoxins. Former Elem Environmental Director and current director of Kennedy Environmental Karola Kennedy said Friday that nine of the 18 water systems that “use Clear Lake as their source water are sampling every other week for microcystin level during bloom season.”
Kennedy said “all finished drinking water results testing for microcystin to date has not exceeded the EPA recommended guideline of 0.3ug/L.”
In 2018, the California State Water Resources Control Board found that every water system sourcing from Clear Lake had barriers protecting against microcystins in place, according to a report shared by Gustafson. No official regulations exist, however, to create a threshold of acceptability in microcystin levels in tap water.
“There is no threshold level,” said Gustafson. “This was the first time the drinking water plants had been scored in this manner. The state water board cannot ask the drinking water plants to add more barriers since they don’t regulate microcystin. They do however, (regulate) odor and color in drinking water, and the same protections that mitigate those issues also mitigate microcystin.”
The tribes’ testing of Clear Lake’s waters began in the years following what Ryan called a “heinous” bloom of cyanobacteria in 2009. “You’d have birds walking on it,” she noted.
That bloom inspired the tribes and other interested parties around the lake to begin collecting information on the blooms.
“We felt a need to do it,” Ryan said. “We wanted to have that information at our fingertips on a regular basis.”
Asked how the cyanobacteria in Clear Lake can be reduced, Ryan pointed to nutrient levels.
“Cyanobacteria, just like algae, are fed by nutrients,” she said, naming phosphorous and nitrogen as two major examples.
If nutrient levels are limited, so is the bacteria. Limiting those levels, however, is a complex task.
A federal Clean Water Act requirement called a “Total Maximum Daily Load” is in place for Clear Lake’s nutrient levels, Ryan noted. The TMDL is meant to force entities responsible for nutrient discharge like the County of Lake, the Bureau of Land Management, the National Forest Service and the cities of Lakeport and Clearlake to bring Clear Lake’s total daily nutrient load down to acceptable levels.
Many of these requirements have not been met, and in 2016, the Central Valley Water Board of California issued TMDL enforcement orders to these entities.
Ryan noted that the county’s grading ordinance, the cities’ requirements for new development near the shoreline, and other rules have been put in place to limit nutrient discharge into Clear Lake.
But, she added, “we need to do more.”
