Blue-Green algae is a serious heath problem for you, your kids and pets that occurs sporadically, especially towards the middle and end of the summer, when water temperatures rise, and nutrients have washed into the near-shore area where docks and beaches are located. Sources of nutrients include the runoff from a fertilized lawn to lake, non-compliant septic systems, campfires on the beach, and especially bathing with soap and shampoo. While the contaminants cause harm to the entire lake, it is your immediate shoreline that will be affected the most. Here are several links that provide more information:
https://www.theswimguide.org/2014/08/07/5-ways-to-protect-yourself-from-blue-green-algae
https://www.pca.state.mn.us/air-water-land-climate/blue-green-algae-and-harmful-algal-blooms