Harmful Algal Blooms Home

Harmful algal blooms occur when normally occurring cyanobacteria in the water multiply quickly to form visible colonies or blooms. These blooms sometimes produce potent cyanotoxins that pose serious health risks to humans and animals.Although most algal blooms are not toxic, some types of cyanobacteria produce nerve or liver toxins. Toxicity is hard to predict in part because a single species of algae can have both toxic and non-toxic strains, and a bloom that tests nontoxic one day can be toxic the next.

Real-Time Monitoring Networks

Check 2019 Monitoring Updates

Track monitoring updates as they are posted.

Protect Yourself

Learn about health risks to people and pets exposed to algal blooms and what you can do to recreate safely.

Learn About HABs

Got questions? Find more info about harmful algal blooms.

Find Guidance Documents

Retrieve helpful guidance documents and response plans. For agencies responding to harmful algal blooms.


Signage & Handouts

Go to Response Agency Resources for more resources.

Warning Sign

Danger. Closed due to toxic algae. Keep out of water.

Danger Sign

HABs info card front
Click for larger view

HABs info card back
Click for larger view

Report a Bloom

24-Hour DEQ Environment Incidents Line: (801) 536-4123

Call Utah Poison Control Center

If you believe you or your pet have been exposed to a harmful algal bloom, call (800) 222-1222.

Click the site icons for details.

2019 Advisories

Location Last Sample Date Advisory Level
Calder Reservoir July 2, 2019 Warning
Matt Warner Reservoir July 16, 2019 Warning
Payson Lakes June 24, 2019 Warning for McClellen Lake
Utah Lake July 10, 2019 Warning

2019 Monitoring Updates

Location Last Sample Date
None None

Get BloomWatch App

Help us track cyanobacteria blooms with your smartphone. Go to cyanos.org for more info.