Spring has sprung, lake fishing season opens April 27, and outdoor enthusiasts will soon begin flocking to area lakes. Before you dive in, it may be wise to check conditions first.

“We have some wonderful lakes here in Jefferson County and there are some great opportunities for fishing, swimming and boating,” said Michael Dawson, water quality manager for the Jefferson County Department of Public Health. “We also have cyanobacteria blooms that happen every year, and people should be aware that sometimes these can be dangerous.”

The four area lakes often most affected are Anderson Lake, Gibbs Lake, Lake Leland and Crocker Lake.

“Cyanobacteria are also known as blue-green algae, and are naturally occurring organisms,” Dawson said. “Most cyanobacteria are beneficial (such as those that fix nitrogen in your garden), but some can produce toxins, including some of the most deadly toxins known, such as anatoxin-a. In our county, several dogs have died after swimming in Anderson Lake, and we have had toxin levels high enough to be very dangerous to humans as well.”

To keep visitors safe, Dawson said environmental health staff monitor the four lakes every Monday from April through October.

“We check other lakes as needed if we get reports of blooms,” Dawson said. “It takes several days to get results back from laboratory testing.” Results, which are posted at
jeffersoncountypublichealth.org/723/Lake-Water-Quality, are usually updated on Thursdays or Fridays.

“We post warning signs at lakes that have blooms, and do press releases,” he added.

As of April 15, Anderson Lake and Lake Leland both showed light algae blooms. Crocker Lake and Gibbs Lake have no blooms visible, according the county website.

Lake conditions can change rapidly and a lake’s status may change since the last sample was taken. Sampling is only done at one access point on a lake and conditions may be different elsewhere on the same lake.

“Regardless of what is posted (on the website), if you observe a green paint-like scum or bloom on a lake, follow the recommendations listed at the warning level,” Dawson said. “We encourage the public to keep their eyes open for signs of cyanobacteria blooms when visiting lakes.”

Any bright green, blue or other colored scum or flecks in the water in a Jefferson County lake should be reported to 360-385-9444, so they can take a sample. In addition to seeing a green paint-like scum on the water, other signs of a toxic bloom may include dead fish, waterfowl, or other animals.

“If you are unsure if it is safe, then avoid contact with the water. Keep children and pets out,” said Dawson. If exposed to a bloom and there are any symptoms, he said to see a health provider. For serious symptoms, such as difficulty breathing, call 911.

If a dog gets algae on its fur, try to rinse it or wipe it off right away and keep it from licking it off. If you take an animal to the vet, let them know about the algae exposure.

Toxic algae blooms contain either neurotoxins, which cause nerve poisoning, or hepatotoxins which causer liver poisoning. Signs of nerve poisoning in humans, may include numbness of the lips, tingling in fingers and toes, and dizziness. In animals, signs may include weakness, staggering, difficulty breathing, convulsions, and death. Signs typically appear within 15–20 minutes after ingestion.

Signs of liver poisoning include abdominal pain, diarrhea, and vomiting in humans and death in animals. It may be hours or days before signs of liver poisoning appear.

Dogs or cats may experience a sudden unexplained sickness or death, especially if it has algae on its mouth, legs, or feet. In addition to the symptoms listed above, humans may experience skin rashes after being in the water.

Toxic blooms in area lakes are not new, Dawson said.

“Anderson Lake has had a toxic bloom every year since monitoring started in 2007,” he said. “We are not certain exactly how long it has had toxic blooms, but a 2021 study found that cyanobacteria were present in lake sediments dated back to the 1700s. Also, the toxin-producing varieties of cyanobacteria have been present in Anderson Lake a long time, although the levels have fluctuated over the decades.”

Eventually the toxins break down in the water and are destroyed naturally.

Dawson said the it’s only relatively recently that health officials have been able to test for algae-related toxins.

“Health officials haven't always known the full risk of exposure to cyanobacteria, nor had the ability to test for toxins such as anatoxin-a, until recent decades,” he said. “The good thing is that the blooms at Anderson Lake have been very regular, so testing has been able to tell us when the toxin level has exceeded state guidance, and signs can be posted in a timely manner.

A lot of visitors are expected for opening day of lake fishing on April 27. Dawson said they will update the website in advance. It will include images of what blooms look like.

To learn about Washington lakes outside of Jefferson County, go to www.nwtoxicalgae.org.