Drinking Water Safety
Potable water is only available seasonally (typically end of May-end of September)in Rock Harbor and Windigo. All surface lake and stream water should be considered contaminated with pathogens. Drinking contaminated water can make you very sick. Water collected at the park should be boiled at a rolling boil for at least one minute or passed through at least a 0.4 micron filter (using a water filter).
In recent years, blue-green algae blooms have occurred seasonally in several inland lakes. Blue-green algae can be toxic, and filtering does not remove toxins from the water. Avoid swimming, fishing, or filtering water if it has a cloudy-blue cast or looks like "pea soup." Report possible algae blooms to park staff. If algae blooms occur, advisories will be posted at park visitor centers, affected lakes and campgrounds, and in website alerts.
Last updated: January 12, 2018