Synura

Algae the cause of lake odor, discolouration

Lab results show three culprits for recent algae bloom on Cowichan Lake.

Though many residents were in disagreement over what was causing the Cowichan Lake’s strange greenish-brown colour, odor and taste, the word is finally in, as the Town of Lake Cowichan’s Public Works and Engineering Department recently received the laboratory results.

The town sent a water sample to Maxxam Analytics in Burnaby, who confirmed that the cause of discolouration was the result of an algae bloom — of a magnitude rarely seen on Cowichan Lake.

The three culprits are Anacystis, Dinobryon and Synura. Synura is in the same algae group as Uroglena, which has been previously identified in Cowichan Lake. Synura and Uroglena are both similar in that they are both colonial golden-brown algae and that individual cells have two flagella. Along with the bad taste and odor, the algae could also clog filters in the lake.

Though many residents opted to buy bottled water due to concerns over how the algae bloom would effect drinking water quality, Island Health lifted its boil water advisory on May 14, eight days after it was issued, as the turbidity of the water was determined to be below 1.0 NTU, the new standard for turbidity for Vancouver Island’s drinking water.

Though the algae bloom on Cowichan Lake has largely faded at this point, residents of Shawnigan Lake have complained of the same problems — discolouration, bad taste and an odor on the water and in the air — with their own lake.

Future boil water advisories will be posted on the Town of Lake Cowichan’s website (www.town.lakecowichan.bc.ca) and the Lake Cowichan Gazette will also post live updates on drinking water quality, when available, through our Facebook page.