Photo: MN DNR

By Laura Durenberger-Grunow - Boreal Community Media - October 6, 2025

An upcoming Twin Ports Climate Conversation webinar will explore the rising issue of harmful algal blooms (HABs) in northeastern Minnesota, including remote inland lakes and Lake Superior. Scheduled for October 14 from noon to 1:00 p.m. via Zoom, the event will feature three researchers who will share their work on the topic.

Harmful algal blooms are becoming more common across Minnesota, according to the Minnesota Department of Natural Resources (DNR). Though often called blue-green algae, the organisms responsible are actually cyanobacteria, which are a natural part of aquatic ecosystems. Under certain environmental conditions, however, these bacteria can rapidly multiply and form dense, potentially toxic blooms.

In a previous interview with Boreal Community Media, Dr. Christopher Filstrup, a limnologist at the University of Minnesota's Natural Resources Research Institute (NRRI) and one of the webinar's presenters, noted that these blooms are now appearing in lakes where they were not previously observed, including some in the Boundary Waters Canoe Area Wilderness (BWCAW) and near the Lake Superior shoreline. He pointed to factors such as warming temperatures, increased thermal stratification, severe weather events, and flood-drought cycles as potential contributors to this trend.

When cyanobacteria bloom, they can produce toxins that are dangerous to people, pets, and wildlife. Exposure can occur through ingestion—whether intentional, accidental, or from contaminated drinking water—as well as through recreational activities. Dogs can get sick from licking cyanobacteria off their coats after leaving the water. Some toxins can also become aerosolized, leading to respiratory exposure.

Dr. Filstrup recommends the Minnesota Pollution Control Agency's (MPCA) guideline: "When in doubt, stay out." If a body of water resembles "pea soup" or has a dense green or blue-green surface scum, it is best to avoid it. It's important to remember that toxins can be present even when there's little visible algae or after a bloom has dispersed.

For community members who may have missed the recent workshop on cyanobacteria led by Dr. Filstrup on August 11, 2025, in Grand Marais, the upcoming webinar offers another opportunity to learn about this topic. 

The Twin Ports Climate Conversation will feature presentations from Dr. Lienne Sethna from the St. Croix Watershed Research Station, Dr. Kaitlin Reinl from the Lake Superior National Estuarine Research Reserve, and Dr. Chris Filstrup from the NRRI. 

Additionally, the DNR shared that a new community science project will be highlighted, which aims to equip volunteers with the tools to track toxic blooms and chloride levels. This network will provide real-time data to help protect lakes and the public. One available resource for community science is the BloomWatch app, which allows users to report and view potential cyanobacteria blooms.

The Minnesota Department of Health (MDH) and the Minnesota Pollution Control Agency (MPCA) are the lead state agencies for HAB response and public guidance. The Grand Portage Band of Lake Superior Chippewa also issues alerts. 

The Twin Ports Climate Conversation series is a quarterly forum organized by the Minnesota Department of Natural Resources, the 1854 Treaty Authority, and Minnesota Sea Grant. The series aims to facilitate community dialogue on climate adaptation and resilience.

To register for the webinar, click Webinar Registration - Zoom. 

For accessibility accommodations or questions, contact Julie McDonnell at (218) 834-1443.