Toxic Algae Alerts

The alert level is based on an assessment of the percentage of river bed covered by cyanobacteria mats at each site. Risk may also be increased by algae mats carried downstream from other sites. Check the alerts page regularly to stay informed. The alert status is updated weekly on a Thursday.

Alert level Health Risk
exposure to cyanobacteria toxins
Extent of cyanobacteria cover Action
Low Low Zero to 20% Most parts of rivers will not have cyanobacteria. Take usual care and be aware of cyanobacteria and risks
Medium Low to moderate 20-50% Blue-green algae levels have increased due to warm settled weather. Keep children and dogs away from the river and its margins where they may come in to contact with algal mats. 
High High 50%+  Blue-green algae levels have increased to warning level due to warm settled weather. Do not swim and keep children and dogs away from the river and its margins where they may come in to contact with algal mats.

Information about what to do during the different alert levels can be found in the Frequently Asked Questions.