Residents are reminded that Jackfish Lake, located in Yellowknife on Highway 3, continues to have elevated levels of arsenic and harmful algae. The water is not safe for swimming, fishing, or other recreational use. Updated warning signage will be installed around Jackfish Lake within the next couple of weeks.

Harmful Algal Blooms (Cyanobacteria):

Since 2013, Cyanobacteria, commonly known as blue-green algae, has been monitored in Jackfish Lake. Cyanobacteria are microscopic organisms that grow naturally in freshwater bodies like lakes and ponds. Some species can produce harmful toxins called cyanotoxins. Under certain conditions—like warm temperatures and high nutrient levels—they can quickly multiply, leading to harmful algal blooms.

Health Risks:

Cyanotoxins can be harmful to people and animals if the contaminated water is:

• Swallowed
• Inhaled as mist or spray
• In contact with skin

Symptoms can include:

• Skin, eye, nose, or throat irritation
• Stomach pain, diarrhea and vomiting
• Headaches, muscle weakness, or fever
• Liver or kidney damage in severe cases

Children are more at risk because they often spend more time in the water and are more likely to accidentally swallow it.

Pets are particularly vulnerable due to their increased likelihood of exposure to water.

Identification:

Cyanobacteria is present in Jackfish Lake at all times of year. Blooms usually appear between mid-August and early September. They are often found in warm, shallow, and slow-moving waters. Cyanobacteria are often blue-green in colour, but some types may appear green-brown, red-brown, or red.

Blooms may look like:

• Green pea soup
• Turquoise paint
• Thick surface scum
• Solid-looking clumps

Blooms may smell bad, like:

• Potent Grass
• Sewage, or
• Rotting garbage

What you can do:

If you see a bloom, assume it contains toxins. To stay safe:

• Do not drink untreated water from lakes, ponds or wetlands
• Do not bathe or swim in discolored, scummy, or smelly water 
• Do not boil lake water with a bloom. This will not remove toxins and may make them more concentrated.
• Do not let pets:
  • Swim, play, or drink in water with a bloom
  • Eat dried algae along the shore
  • Lick their fur after contact with a bloom
• Rinse yourself and your pet with clean tap water as soon as possible if you come into contact with a bloom
• Keep children and pets away from affected areas
• Use clean, treated, or bottled water for drinking and cooking

Report suspected blooms to your Regional Environment and Climate Change Office.

Arsenic in Yellowknife-Area Lakes

Arsenic is a natural element in our environment. It is found at low levels in the soil, sediment, snow, plants, mushrooms, rocks, water, fish, and wildlife across the NWT. In some locations, such as the Yellowknife area, arsenic levels are naturally higher than in other places, due to the local geology. However, historical gold mining activities, particularly in the Yellowknife area, have released large amounts of additional arsenic into the environment, including certain lakes.

Safety Guidelines:

Based on current environmental and human health data, avoid swimming, fishing, or harvesting berries, mushrooms and other edible plants in and around these lakes:

• Jackfish Lake
• David Lake
• Fox Lake
• Frame Lake
• Gar Lake
• Handle Lake
• Kam Lake
• Niven Lake
• Peg Lake
• Meg Lake
• Rat Lake

More information can be found here.

While occasional exposure to lakes with arsenic levels above Health Canada's drinking water guidelines may not pose significant health risks, it is recommended not to drink untreated water from any lake.

For more information or to report environmental health concerns, contact the Department of Health and Social Services or visit www.hss.gov.nt.ca.

Helpful Links

• Environmental Contaminants
• Harmful Algal Blooms, Cyanobacteria and Cyanotoxins in Surface Water
• Arsenic in Lake Water Around Yellowknife

For media requests, please contact:
ECC Communications
Environment and Climate Change
Government of the Northwest Territories
ECC_Communications@gov.nt.ca

Backgrounder: Jackfish Lake Power Generation Facility  

• Research and monitoring indicate that the high concentrations of cyanobacteria in Jackfish Lake are a result of the combination of physical characteristics of the lake (i.e., small size, limited water flow, and historical environmental impacts of nearby land uses).
• Historical evidence has shown that the Northwest Territories Power Corporation’s (NTPC) operation of the Jackfish Lake Power Generation Facility (power plant) is not solely responsible for the proliferation of cyanobacteria in Jackfish Lake. Surrounding land use, including the Yellowknife landfill site, road networks, and cemetery, are also likely contributing nutrients to the lake.
• Industrial processes can alter water temperature; however, temperature effects alone are not enough to create an algal bloom. 
• NTPC holds a Type A Water License to authorize the use of water from Jackfish Lake for generator cooling purposes and monitors thermal effects to Jackfish Lake.
• Results have shown that thermal effects are contained to the plant discharge location, forming a thermal plume when the plant is operating.