Current & Historical Microcystin Levels in Grand Lake St. Marys
* Current numbers are averages. Microcystin levels vary at different lake locations. Courtesy Dr. Stephen Jacquemin, Wright State University-Lake Campus
Frequently Asked Questions
Micrograms per liter.
Parts per billion, or ppb, represents the amount of microcystin in a billion parts of water. In other words, it is the concentration of microcystin. The conversion of ppb to ug/L is 1:1, which means that 10ppb = 10 ug/L. Essentially, it’s two different ways to say the same thing.
The World Health Organization says water is safe to swim in at or under 20 ug/L. However, the State of Ohio puts the threshold at 8 ug/L.