Known for its clear warm water and extensive shoreline, Shuswap Lake in B.C.’s southern Interior is an outdoor paradise for many people during the hot summer months.

But last July, a rare phenomenon occurred when a large algal bloom filled most of the Salmon Arm end of the lake, turning the pristine water into pea soup for several weeks.  

“We’ve never seen anything quite like that. We’re still trying to fully understand the cause,” said Mike Sokal, a water quality limnologist for B.C.’s Ministry of Environment and Climate Change Strategy. “The lake was visually unappealing, but health officials noted the water was safe for all recreational activities and public drinking water systems.”

Ranging in size from microscopic single cells to large seaweeds, algae are a natural part of all aquatic ecosystems, providing food for fish and supplying much of the oxygen we breathe. However, prolific growth can cause a dense mass or bloom to form. Most of the blooms are harmless, according to Sokal, but some species have the potential to produce toxins that can be dangerous to people, pets or livestock.

To better understand where and when algae blooms happen around the province, the ministry has developed the educational Algae Watch website. People are invited to contribute information to create a comprehensive picture of B.C.’s algae situation. The website helps people recognize potentially harmful algae blooms and differentiate algae blooms from other natural phenomena, such as foam or pollen, which can sometimes look like blooms.

People can also use the online submission form to provide information on the location, extent and photos of an algae bloom, and access links to provincial health authorities in the event of a blue-green algae (cyanobacteria) bloom. The data collected will help scientists like Sokal determine future water-monitoring programs.

“The website can help us track changes over time and identify areas of the province that are getting more algae blooms. We can then start investigating what’s causing these changes,” said Sokal, who receives calls every year from people concerned about algae at their local lake. “It’s really encouraging to see people interested in what’s happening at their lake. Some of those concerned citizens become champions for the lake and start local sampling programs.”

Norm Zirnhelt is accustomed to seeing algae blooms every summer on the nutrient rich Opheim Lake, which has been naturally prone to blooms for decades. Living on a farm along the lake in B.C.’s Interior, Zirnhelt keeps a close eye on the water and has to be careful his livestock don’t drink it whenever the blooms blow onto shore.

As the executive director of the B.C. Lake Stewardship Society (BCLSS), Zirnhelt encourages everyone to pay attention to what’s happening on their local lake and report anything unusual to the Province.

“Lakes are susceptible to impacts from all kinds of human land uses and activities, so it’s really important that there’s some vigilance on those activities. If there are any changes that might be occurring in a lake, citizens can be an early detection or early warning mechanism,” Zirnhelt said. “In the Cariboo region of the province, there a number of lakes that are susceptible to algae blooms. These blooms can occur naturally or can be the result of land use activities causing nutrient enrichment of lakes. People need to be careful and regard them as all potentially toxic.”

Anyone with immediate concerns related to drinking and/or recreational water use is asked to contact their local health authority.

Quick Facts:

• Most algae blooms form when there are increased nutrients, warmer temperatures, abundant light and stable wind conditions. Some human activities, such as agricultural run-off or improperly placed or poorly functioning septic systems, can also make blooms more likely.
• Cyanobacteria (also known as blue-green algae) blooms are of particular concern since there are several species capable of producing toxins that can be harmful to humans, domestic animals and livestock.
• Fifty-three lakes throughout B.C. are being monitored through the BC Lake Monitoring Program, which reports long-term changes to the lakes' water quality, to help determine the best way to manage and protect them. The ministry also co-ordinates the Volunteer Lake Monitoring Program in partnership with the BCLSS, which supports stewardship groups and individuals with various levels of monitoring on more than 40 lakes around the province.

Learn More:

Visit the Algae Watch website: www.gov.bc.ca/algaewatch

For more information about lake monitoring programs in B.C., visit: www.gov.bc.ca/lakemonitoring

For more information about toxic algae blooms, visit: https://www.healthlinkbc.ca/healthlinkbc-files/blue-green-algae

For more information about the BCLSS, visit: https://www.bclss.org/