Canals in the Tahoe Keys are plagued by blue-green algae. Photo/Kathryn Reed

By Kathryn Reed

A toxic algae bloom is covering a large swath of the Tahoe Keys, prompting a warning to people to be wary of the water.

Officials with the Tahoe Keys have known about the blue-green algae since Aug. 11. Warnings, though, did not start until Aug. 23.

For such a big problem, the caution signs are very tiny.

“It’s in different locations in the west lagoons,” Kirk Wooldridge, general manager for the Tahoe Keys Property Management Association, told Lake Tahoe News. “It’s in various degrees in different areas. It depends on sunlight, current and depth.”

Some warning signs are in Spanish, but most are just in English. Photo/Kathryn Reed

On Wednesday the Lahontan Regional Water Quality Control Board encouraged signs be posted alerting people to the danger. Driving by it is near impossible to see them, but out with a dog is a different story.

“The level tested at Tahoe Keys did not show a high danger level. It was at the much lower caution level,” Doug Smith with Lahontan told Lake Tahoe News.

There are three levels of danger for cyanobacteria, which is better known as blue-green algae. The toxicity in the canals of this South Lake Tahoe neighborhood are at the lowest level.

Still, the “caution warning” includes: humans and dogs should not come in contact with the algae or scum on the shoreline, neither people nor pets should drink the water, fish caught in the area should be cleaned with tap/bottle water before cooking, no shellfish should be eaten from these waters, and the water should not be used for cooking.

More dangerous toxic levels can cause eye irritation, skin rashes, mouth ulcers, vomiting, diarrhea, and flu-like symptoms. Two dogs in Napa County died this summer after drinking water from a pond with the algae.

“Blue-green algae naturally occur everywhere in the environment. We don’t know the exact reason why certain areas have blooms,” Smith said.

Outbreaks have been occurring throughout California this year.

Contact with the water of a large swath of the Tahoe Keys lagoons could be dangerous because of the algae bloom. Photo/Kathryn Reed

Why it goes away also isn’t known.

The plan is to continue field tests. If those have indicators that the level of toxicity is rising, it will be sent to the lab for definitive proof.

This is not something the Tahoe Regional Planning Agency or El Dorado County Environmental Health regulate.

“TRPA is aware of this concerning development and working closely with the Lahontan Water Board, who has jurisdiction on this matter, to monitor the situation and make sure that appropriate steps are taken to protect public health, safety, and the environment,” Tom Lotshaw with TRPA told Lake Tahoe News.

Copper sulfate is a proven herbicide that kills the algae. Applications have worked in other jurisdictions under Lahontan’s oversight. An emergency provision in Lahontan’s Lake Tahoe Basin Plan would allow the use, but the danger level would have to increase substantially for that option to be on the table.

It is not known if the algae can be spread by watercraft, but boat travel has not been halted. It could be that if it were to get into Lake Tahoe, it would die because of the colder water temperature.

The Keys put up a boom on a canal linking the regular homeowners with the Lighthouse Shores gated community. According to Wooldridge, it didn’t do any good. The algae went under the boom.

He did not know how deep the muck goes.

The waterway at Venice and Alpine drives looks like a holding pond for a toxic chemical plant with the eerie green color and swirls along the shore.