Cyanobacteria in a deep well contaminates community water source

Observation by Dave Tamblyn:

Cyanobacteria are generally considered obligatory photosynthesizers. You’re seeing a picture from a helicopter flying over the well/treatment plant. The main point is that there are ponds very close to the well. But it turns out, we don’t believe those ponds are the source of the cyanobacteria in the well. In fact, we don’t really have a good answer to how the cyanobacteria got 140 ft underground. Because the cyanobacteria concentration was very high, above secondary contact levels, bottled water was considered infeasible. With no second water source, the whole community was evacuated for 26 days.

The reason they couldn’t use bottled water was that the water was 5 times the recreational water guideline for primary contact. So, the Medical Health Officers decided that if it wasn’t acceptable for swimming, then it shouldn’t be acceptable for bathing and showering. The community affected was Ukwanalis Village at Kingcome Inlet, which pertains to the Dzawada'enuxw First Nation. You can also link to a news report. https://www.cbc.ca/news/canada/british-columbia/b-c-first-nations-village-evacuated-after-blue-green-algae-found-in-water-source-1.5468819

I’m making the report here on LEO because the news didn’t stress how rare it is to find cyanobacteria is a deep well source. The main genus identified was Aphanothece with occasional Synechococcus (1000 times less populous). Cyanotoxins never exceeded drinking water guidelines when tested. The highest measured concentration was 541,000 cells per mL, in Jan 2020 in the community water distribution system.

The attached pic (credit G. Luttrell) shows some of the remedial work carried out by Indigenous Services Canada, specifically the installation of a bentonite clay surface seal to prevent contaminants travelling down the well casing.