Cyanobacteria bloom under lake ice

Observation by Dave Tamblyn:

Cyanobacteria blooms usually occur in summer. This event was described to me by a local resident. The date is approximate. The location is Kirby Lake, which is used as sole drinking water source for a small community. There is no treatment in place to address cyanobacteria blooms. Subsequently, in about 2014, the community installed bubblers at the bottom of the lake to reduce the risk of blooms.