HAB Recreational Awareness, Algal Mat Alerts, & Advisory Signs

Be Aware of Algae Blooms

Public access points where blooms have been known to occur may be posted with educational awareness signs such as this. This sign is recommended for locations where cyanobacteria blooms are known to occur and may be used year-round to raise awareness.







Algal Mat Alert

These signs will be placed at access points in the vicinity of waterbodies experiencing an observed cyanobacteria mat harmful algae bloom. These mats will typically retain the toxin which the cyanobacteria may be producing and therefore toxins in the water column are generally very low or below detectable levels. Therefore, avoiding contact with mat material and preventing children and pets from consuming mat material in the water or washed alongshore, should allow the recreational use of the waterbody to continue.







Cyanobacteria Warning Sign

En Español

The Health Department will use the “Warning” sign to indicate that a harmful algae bloom is present which exceeds recreational advisory guidance thresholds  (≥40,000 cells Microcystis species or ≥100,000 cells/ml total toxigenic cyanobacteria species) which are levels capable of producing toxins harmful to human health, or observed microcystin concentrations ≥ 8ug/mL, cylindrospermopsin concentrations ≥ 15 ug/mL, or the water has visible algae scums or mats.

At this level, the HAB Task Force initiates or continues monitoring and the local health department is recommended to issue a public notification to avoid all contact with the waterbody affected by the bloom.

Areas with high-recreational use such as beaches, boat ramps, and marinas are ideal posting locations. This sign should only be used when there is an active cyanobacteria advisory.




Animal Safety Alert Poster

CDC Poster for raising awareness of the potential risk which cyanobacteria blooms may pose to pets or other animals.

Additional sizing options and the ability to order hard copies at CDC’s website.