Cyanobacteria, also known as blue-green algae, can produce toxins and deplete lakes of oxygen when they die. It can be dangerous for both pets and people. In August 2014, nearly half a million people in the Toledo area were without tap water for nearly three days due to contaminated drinking water. A type of blue-green algae, Microcystis, had produced particularly high levels of the liver toxin microcystin (MC) in Lake Erie.Since
the nutrient phosphorus
is an important nutrient for these algae, and environmentalists and the politicians they influence don't understand biological systems thinking, they have made efforts to reduce phosphorus levels and inhibit the growth of cyanobacteria.