Harmful Algal Bloom Observations

Welcome to the Montana Harmful Algal Bloom reporting application

• This site will allow you to report an algal bloom that you have observed using the  Report  form and also review current and past observations using the interactive  Map Viewer  found below.
• DEQ will issue the appropriate advisory when a harmful algal bloom is visually confirmed to be present and for two weeks thereafter.

Use the Report Form below to report a potential bloom that you have observed. A member of Montana DEQ staff will be automatically notified to review your observation and take the appropriate next steps.

The Harmful Algal Bloom Map Viewer allows you to explore past observations, look through current advisories, or view reports from specific lakes and streams. Use the selection tools at the top of the map to narrow down your results, or simply explore the map and tap on points of interest to view information about reported algal blooms in your area.

 For additional information and resources visit the Montana Harmful Algal Bloom Website 

 Caution and Closure Specific Guidance 

Disclaimer

These are public reports of algal blooms. Reports do not represent a comprehensive list of all HABs. Advisories (caution or closure) are issued by experts, but it is impossible to keep the status of each report perfectly up-to-date. Toxin production may occur or dissipate at any moment. Err on the side of caution, and if in doubt, just stay out.