Algal blooms come in a rainbow of colors, caused by a slew of algae and bacterial species that multiply exponentially with enough sun, slow-moving water and nutrients like phosphorous and nitrogen that commonly come from fertilizers, wastewater and fossil fuels. While most are merely inconvenient and kind of gross to humans, some blooms can cause neurological complications, respiratory problems and rashes.
St. Croix River separating Minnesota from Wisconsin turns dull as a slimy green sheen overtakes it like a shabby coating of tinted plastic wrap. Likely a result of runoff from the agricultural lands surrounding the river, these algal blooms shut down beaches, denying schoolchildren newly free for summer break from one of the few amusements in the sleepy towns surrounding the river. At the camp I attended for 10 summers, we swam in it anyway, the algae staining green polka dots into the lining of our swimsuits.As if to mark the passing of spring into summer, every year the mirror-clear surface of the