For the last few months California water officials have been busy taking water samples of an often very noticeable green sludge. Commonly referred to as blue-green algae, the muck can be toxic, and lately it’s been in many of California’s reservoirs and lakes, including Lake Oroville and Lake Shasta.
Actually a bacteria known as cyanobacteria, blue-green algae is naturally occurring in water bodies and usually goes unnoticed. But when conditions are just right, the bacteria rapidly grows and become highly visible. This is known as a bloom — and in some cases it can be dangerous.
Beverley Anderson-Abbs, an environmental scientist with the State Water Board, said it’s not clear why California is seeing an uptick in blooms.
“There are various hypotheses about why it’s happening, but nobody knows for sure," she said.
She estimates that there are currently more than 40 blooms in California when taking into account those reportedand those not reported that are on private lands. She says the drought, climate change and high amounts of nitrogen and phosphorus in water bodies could all be contributing to the issue. One thing is for sure though, she said.
“It seems to be a more toxic year than we’ve seen in the past," Anderson-Abbs said.
That’s the real problem: the toxins that some cyanobacteria produce. In Northern California, Anderson-Abbs says the most common toxin is anatoxin-a. So far she says it’s only been reported in low levels.
“So anatoxin not really high, but still worrisome because it can be problematic with dogs and wildlife and livestock that tend to drink a fair bit of water," she said.
According to an email from the California Department of Public Health, death in animals can occur within minutes or hours after contact with contaminated water. In a recent press release CDPH reports the toxins can be deadly to humans and can cause serious damage to the liver, kidneys and nervous system.
Drinking water has not been affected, Anderson-Abbs said. Right now in California the concern is mainly for boaters and swimmers.
Looking at other countries who have been dealing with this issue for longer than the U.S. – the concern could be a new normal, she said.
“In Australia they’ve been dealing with cyanobacteria blooms for 25 or 30 years, and they’ve just watched it steadily increase. The blooms have lasted longer, they’ve become more toxic, they’ve invaded more water bodies, and we’ve started seeing those same kinds of patterns here," Anderson-Abbs said. "So if we continue to get warmer temperatures as we have over the last 8 or 10 years and certainly if we get drought years we are very likely to continue seeing this pattern."
If we continue to get warmer temperatures as we have over the last 8 or 10 years, and certainly if we get drought years, we are very likely to continue seeing this pattern. — Beverley Anderson-Abbs, environmental scientist
This summer four lakes and reservoirs in the North State have reported blue-green algal blooms: Mountain Meadows Reservoir, Lake Britton and Lake Oroville and Lake Shasta.
According to Eric See, an environmental program manager with the California Department of Water Resources, the bloom in Oroville has dissipated. It was in the Middle Fork Arm of the river and lasted for about a month officially ending August 22.
Lake Shasta's bloom, however, is ongoing.
The first bloom at Lake Shasta was in the Pit River Arm of the lake, but now there are other areas that contain anatoxin-a. Clint Snyder, assistant executive officer of the Central Valley Water Board, said the biggest thing to note is that the newly affected areas are invisible, which is a stark contrast to the bright-green pea soup color that usually warns of a bloom and possible toxins in the area.
“The public’s not going to be able to see it like they were able to see, or they currently are able to see the bloom in the far upper reaches of the Pit Arm," Snyder said. "So this area would look like any area of the lake un-impacted however anatoxin-a is present there.”
Newly affected areas include water near Jones Valley Resort, Silverthorn Resort and the Squaw Creek Arm of the lake. The bloom in the Pit River Arm of the lake also still exists.
Snyder says the levels of toxins in all areas are still too low to be considered harmful to humans, but they could be harmful to animals. He says signs will be posted in the affected areas and that people don't need to cancel their Labor Day lake plans.
“Again the concern here is for pets," Snyder said. "As long as they’re paying attention to the caution signs and heading those warnings they should have a great time up there.”
Stay Safe In Waters Impacted By Cyanobacteria
- Keep pets and livestock out of the water. Do not allow them to drink the water or eat algal material on shore. If they do get in the water, do not let them drink the water, swim through algae, scums or mats, or lick their fur after going in the water. Rinse pets in clean water to remove algae and toxins from fur.
- Avoid areas of accumulated algae, scums or mats when wading, swimming, or jet or water skiing.
- Do not drink untreated surface water from these areas or use it for cooking; people should not eat mussels or other shell fish collected from these areas. Limit or avoid eating fish from these areas; if fish are consumed, remove the guts and liver, and rinse filets in clean drinking water.
- Get medical treatment immediately if you think that you, your pet, or livestock might have been poisoned by cyanobacteria toxins. Be sure to alert the medical professional to the possible exposure with cyanobacteria. Also, make sure to contact the local county public health department.
Recommendations from the Statewide Guidance on Cyanobacteria and Harmful Algal Blooms