Scientists at Michigan Tech Research Institute report their analysis of satellite images finds both Lake Huron and Lake Michigan waters are 20 percent clearer than they were two decades ago. During that time period, they have surpassed Lake Superior in water clarity. Reduction in phosphorous runoff, and increase in invasive zebra and quagga mussels and climate change are being given credit for clearing things up. Improved clarity is not all good. It could lead to an increase in a type of algae which grows botulism toxins which kill birds and fish.