Climate Change May Worsen Green Lake's Algae Blooms

If you’re a Green Lake regular, you may have noticed the public health alerts on placards around the lake, warning you not to tread where neon green algae blooms have blossomed.

That shouldn’t be surprising, as toxic blooms have prompted public health alerts across the Northwest every summer – including at Lake Sammamish – but a Northwest scientist argues that pollution and climate change may be making freshwater algae blooms more toxic.

Related: More coverage on algal blooms from EarthFix

Oregon State University researcher Tim Otten’s article in the journal Science concludes that fertilizer pollution, wastewater, and a warming climate are fueling the growth of huge mats of green scum in lakes and reservoirs.

“For instance in Lake Erie (Mich.), it’s been plagued with toxic blooms that are so large you can see them from outer space,” Otten said.

Algae can pose a risk to drinking water because some species, notably cyanobacteria or blue-green algae, release powerful liver toxins and nerve toxins. A toxin called microsystin is particularly common.

Otten’s Science analysis suggests that microsystin helps the algae protect itself from cell damage that can occur when reactive forms of oxygen develop in the water. The protective effect gives toxic cyanobacteria a competitive advantage over non-toxic algae.

Cyanobacteria have been around for more than two billion years and Otten says scientists had long puzzled over why blue-green algae produce toxins.

“They’re some of the oldest organisms on the planet, and they actually pre-date any predators that may try to eat them,” Otten said.

More recently, algae blooms have affected Dexter Reservoir, the source of drinking water for the community of Lowell, Ore. In Southern Oregon’s Klamath Basin, harmful algal blooms contribute to poor water quality that harms endangered suckerfish.

Washington state regularly monitors harmful algal blooms in both the freshwater and the marine environments, and in particular focuses on toxins that impact the state’s shellfish industry. Oregon used to monitor harmful algal blooms, but the state has dramatically scaled back its program after losing grant funding from both the National Oceanic and Atmospheric Administration and the Centers for Disease Control.