Clear Lake getting some relief from algae

Clear Lake is suffering from a particularly putrid algal bloom that has created a sewer-like stench.

"We are having a cyanobacteria bloom," said Carolyn Ruttan, invasive species program coordinator for the Lake County Water Resources Department.

After more than a month, the stinky infestation finally appears to be on the decline, she said. But it could rebound.

"Maybe, maybe not. Who knows," said Ruttan, noting very little is known about the ancient organism that is commonly called blue-green algae, but is actually a cyanobacteria. Its green color comes from one of the earliest forms of chlorophyll, she said.

Clear Lake is unlucky enough to have problems with multiple types of algae, weeds and cyanobacteria. Lake County officials have been mowing, poisoning and aerating the pesky plants that can clog motors.

But this particular cyanobacteria — Lyngbya spirulinoides — gets most of the attention because it emits hydrogen sulfide gas that smells much like rotten eggs as it decays. It's a hard smell to ignore and one that seems to stick to hair and clothing.

The stench is concentrated along Clear Lake's shore, where the decomposing bacteria form thick mats that defy attempts to disperse.

This year's infestation is about the same type and size of bloom that kept residents indoors and tourists away from the lake two years ago, Ruttan said.

That bloom was considered the worst in at least 20 years. Some residents believe it's even nastier this year.

Ruttan said she receives about 10 phone calls a day from people asking when it will go away.

"I don't know," she said.

Little is known about the bacteria and what causes it to proliferate, Ruttan said.

"It's very frustrating," she said.

One theory is that it gets worse when lake levels are low and temperatures are hotter than normal. But lake levels this summer are high and temperatures cooler than usual, casting serious doubt on that theory, Ruttan said.

"We don't know what triggers" the blooms, she said.

But they seem to be increasing around the world and are believed to be linked to global warming, Ruttan said.

It's ironic that cyanobacteria is so ancient yet so little is known about it, she said.

Ruttan is trying to drum up interest in scientific studies on Clear Lake's plants and organisms and whether any of it is useful. A cyanobacteria related to Clear Lake's stinky variety is believed to be a cancer inhibitor. It's harvested and sold as a health supplement.

"We could keep hundreds of graduate students busy" studying the lake, Ruttan said.

You can reach Staff Writer Glenda Anderson at 462-6473 or glenda.anderson@pressdemocrat.com.