Look Out For Harmful Algal Blooms When Recreating This Summer
Reporting Suspected Blooms Helps Alert Others
July 5, 2023 | View PDF
Helena - When recreating on Montana's waterbodies this spring, summer and fall, be on the lookout for harmful algal blooms (HABs) that can occur on Montana's reservoirs and lakes. While not all algal blooms contain toxins, the blooms can impact human health and the health of freshwater ecosystems. Report suspected HABs at HAB.mt.gov to help others be alert and prevent illness.
How to identify HAB:
• A coloration or scum on the surface of the water that can look like grass clippings or spilled paint.
• Blooms are often blue, green or gold in color.
HABs can occur when there is a rapid overgrowth of blue-green algae (also called cyanobacteria). The blue-green algae can produce toxins that can cause skin irritation, sicken humans and even kill pets and livestock if ingested. Toxins do not always occur with a HAB and water quality samples are the only way to determine if toxins are present. Blue-green algae are native to Montana and commonly occur at low, safe densities in many freshwater systems.
When in doubt, stay out. Do not drink, swallow, or swim in water that shows signs of HAB and keep kids, pets and livestock out. Direct contact, ingestion, or inhalation of the toxins may irritate the skin, eyes, nose, throat and respiratory system, or cause nausea, vomiting, diarrhea, headache, dizziness, muscle weakness or liver and kidney damage. If you suspect an HAB-related illness in a person or animal, including livestock, call your health care provider or veterinarian immediately.
The Montana Department of Environmental Quality (DEQ) and Department of Public Health and Human Services (DPHHS) maintain a website where people can submit reports of suspected HABs at: HAB.mt.gov.
Before recreating in a waterbody, Montanans and visitors can check the website and view a map of reported blooms, any associated health advisories and monitoring data associated with reports. The site also has photos and information to educate yourself on how to identify HAB. If you suspect HAB, submit a report to HAB.mt.gov and state agencies will work with the local jurisdiction to sample for the presence of toxins and monitor the incident. These reports are important for the health and safety of recreators and water users in the state, and they also help state agencies track where nutrient pollution may be an issue.
Nutrients like nitrogen and phosphorus fuel algae growth and potential HABs. Below are actions you can take to reduce nutrient pollution in Montana's waters:
• Reduce your use of lawn or crop fertilizers.
• Avoid trampling streamside vegetation when you're recreating.
• If you live alongside a stream or lake - restore and protect native woody plants, flowers and grasses because they help filter pollution and stabilize land.
• If your home relies on a septic system, have it regularly serviced and consider upgrading it to a higher-level treatment system.
Throughout the summer, DEQ will post confirmed HABs on Facebook. Follow @MTDEQ for updates.