Lake Superior cyanobacterial bloom reports, 2012 - present

Lake Superior is a cold, oligotrophic lake. It is the largest freshwater lake in the world by surface area and the largest of the Laurentian Great Lakes with binational (United States and Canada) and multi-state (Michigan, Wisconsin, Minnesota) borders. Lake Superior is a globally important freshwater resource. Beginning in 2012, researchers and resource managers began receiving reports of cyanobacterial blooms in the western arm of the Lake. Cyanobacterial blooms have been reported nearly every year since. The purpose of this dataset is to collect observations of cyanobacterial blooms for Lake Superior and connecting waters, document patterns in their occurrence, and provide insights into their causes. For this dataset, a cyanobacterial bloom is defined as an aggregation of cyanobacterial biomass in some or all of the water column, which may lead to the occurrence of surface scums or subsurface maximums. This dataset relies on observations, data, photographs, and insights from a wide range of agency staff and individual members of the public with key input from participants in the Lake Superior Algal Bloom and Nutrient Subgroup collaboration. This dataset only includes reported blooms, and likely doesn’t include all actual bloom events. Additionally, there may be more than one report for a single bloom event, depending on its size. For example, in 2018 there was a widespread bloom event which resulted in numerous reports. Interpretation of this dataset should incorporate these nuances. Observations in the dataset were assigned one of four verification statuses to communicate the level of certainty in the cyanobacterial bloom event. Additional information on taxonomy and/or toxin analyses can be made available upon request.