Chris Otto, a water resources biologist at Sleeping Bear Dunes National Lakeshore, is keeping a close eye on North Bar Lake in late July and early August—often the warmest time of the summer—for greenish algal blooms and signs of cynobacteria at the popular swimming destination.

Avian botulism returned to Lake Michigan this year, killing more species and lasting longer than other recent outbreaks, according to state wildlife officials and researchers. The increase came after a two-year lull. The outbreaks first hit Sleeping Bear Dunes National Lakeshore in Benzie and Leelanau counties in 2006. The die-offs rapidly spread across northern Lake Michigan shorelines and killed an estimated 8,000 to 10,000 birds in 2007.