Blue-green algae indicated as cause of fish kill in Douglas Lake

By on August 25, 2017
Numerous fish carcases were discovered at Douglas Lake on Aug. 11. (Herald file photo).

Water samples taken by the First Nations Health Authority have indicated blue-green algae to be responsible for killing fish found at the mouth of Douglas Lake and the Nicola River earlier this month.

“We’re pretty confident that’s the cause of the fish kill given the lab results,” said Upper Nicola Band (UNB) councillor Brian Holmes.

Due to the health authority’s findings, the algae advisory issued by the band remains in place, Holmes told the Herald.

“Blue-green algae creates a toxin that’s harmful to humans, animals and what not, so our advisory is still in place,” said Holmes.

An algae bloom was found at the mouth of the lake near where the dead fish were discovered, but it has since cleared up due to wind and rain, said Holmes.

Four species of fish were identified amongst the carcasses — sucker fish, white fish, prickly sculpin and shiners.

Further testing on the level of toxins in the algae is being conducted, Holmes said, adding that those results will determine how much more testing and monitoring the band will conduct.

For now, people and their pets are asked to avoid algae blooms and, if contact is made, to wash the affected area with tap water immediately.

“Just to stay out of the water for now,” said UNB Chief Harvey McLeod.

The band has put up signage regarding the algae advisory and no one has been going in the water, said Holmes.

The advisory is only in place for Upper Nicola Band members living on the Douglas Lake reserve at the southern end of the lake, Holmes said.

Douglas Lake (Photo courtesy of Google Maps)

“That’s the only place that we had found fish kill,” said Holmes.

The band has been working with the First Nations Health Authority and a fishery biologist from Nicola Tribal Association on this file, and the Ministry of Environment is being kept abreast of the situation, Holmes said.

Blue-green algae are bacteria that grow in shallow, slow moving or still water, and this bloom was discovered during a period of stagnant weather in the Nicola Valley.

Blue-green algae blooms occur naturally. However, water bodies enriched with nutrients from human activities such as municipal, industrial or agricultural sources are much more likely to have blooms, according to Healthlink BC.

Holmes said he thinks the amount of land that was washed out during this year’s flooding season may have contributed to having higher levels of nitrogen in the lake.

Some blue-green algae blooms can produce chemicals that are poisonous if swallowed by people, pets or livestock while other blooms can have no noticeable effect. Several types of toxins can be produced, including neurotoxins and hepatoxins.

Neurotoxins affect the nervous and respiratory symptoms, causing death only in extreme cases. Hepatoxins affect the liver and can take days before symptoms appear after drinking affected water.

Chief McLeod said the band gets its drinking water from a well and not Douglas Lake.

The investigation began back on August 11 when a band member observed some dead fish floating down the river from the mouth the lake, said Holmes.

“I went and investigated and there was some fish starting to turn up,” said Holmes adding that the algae advisory was put in place as a precautionary measure after that.

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