Rock County Algal Bloom Watch

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The following information is an experimental observation of potential algal blooms through satellite imagery of Lake Koshkonong. This data is updated by the Rock County Public Health Department on weekday mornings during summer months and reflects satellite imagery of the most recent days of data available. Dark red colors represent higher levels of cyanobacteria bacteria that could indicate harmful algal blooms, although not all algal blooms produce toxicity issues. Be aware that the intensity and location of algal blooms can change often throughout any day depending on water temperature, water quality, and wind speed and direction.

Due to seasonal changes, the updates will resume in Spring 2025.

Disclaimer: This is an experimental representation of the potential for algal bloom presence and is not actual measurement of the toxicity that may be present from harmful algal blooms.

Level of Potential Algal Bloom

LOW Blooms may be present - be aware

MEDIUM Consider limiting swimming & keep pets out of water

HIGH Keep pets & children out of water when algae is present. Avoid ingestion of water. If exposed to water, rinse off thoroughly.

VERY HIGH Avoid direct exposure to water, especially children & pets. If exposed to water, rinse off immediately. Be aware of algae-related illness symptoms.