The Bear Lake Algae Bloom

 

What is it?

Lake Alpine Water Company (LAWC) sent a sample of the algae and water to a researcher at Fresno State University and it was identified as the Anabaena genus.  These are filamentous cyanobacteria capable of fixing atmospheric nitrogen. It is planktonic, meaning it floats in the water, being moved by wind and waves without its own source of motility.

 

What causes a bloom?

Blue-green algal blooms happen when there are high nutrient levels, low flows in rivers, low wind and high temperatures.  Although the annual lab analysis of Bear Lake indicated undetectable levels of nitrogen, this algae can fix nitrogen from the atmosphere.  One of the most important factors triggering blue-green algal blooms appears to be a lack of mixing of surface and deeper water layers in a reservoir. In lakes and reservoirs mixing is mainly controlled by wind and temperature. Through the summer months the surface waters heat up resulting in a warmer top layer and cooler bottom layer which do not mix.

 

Is it affecting the drinking water?

No.  Since the algae floats on the water surface and the intake gate for the treatment plant water is seven feet from the bottom of the lake, the algae bloom is currently not affecting the drinking water.  LAWC is continuing to monitor turbidity, color, odor and pH as usual.  All lab tests and analysis at the treatment plant are normal.

 

What are the concerns?

Anabaena is one of four genera of bluegreen algae capable of producing neurotoxins.  Not all algae blooms are toxic.  It is not known what triggers toxin production. The Bear Lake algae is of the Genus Anabaena but the species has not yet been identified and it is not yet known if it is producing toxins.  Toxins can be harmful and fatal to animals but no human deaths have been directly associated with these cyanotoxins however they may cause skin irritations or nausea.  

Standard precautions you can take include not drinking or swimming in the raw water and not allowing your pet to go in the water or drink the water. 

The water processed through the treatment plant and delivered through the tanks remains safe to drink. 

 

Will the algae bloom be treated?

The California Department of Public Health has directed Lake Alpine Water Company to take no action to combat the algae bloom unless there are indications that the water delivered to customers is affected.  If the autumn rains are significant enough, they may flush the algae bloom out of the lake and over the spillway.  Over the winter, the algae will die back in the cold temperatures. 

 

If you have any questions, observations or comments about Bear Lake, please contact the LAWC office via phone at 209-753-2409 or email at info@lakealpinewater.com.  Thank you.

 

 

 

 

 

Cheers-

 

Kimi Johnson

Office Manager

Lake Alpine Water Company

209-753-2409