Jesus Campanero Jr. was a teenager when he noticed there was something in the water. He once found a rash all over his body after a swim in nearby Clear Lake, the largest freshwater lake in California. During summertime, an unbearable smell would waft through the air. … Then, in 2017, came the headlines, after hundreds of fish washed up dead on the shore. … The culprit? Harmful algal blooms (HABs). Often marked by unsightly layers of blue-green scum, these blooms happen when certain algae or microbes called cyanobacteria grow out of control, fueled by warm temperatures and phosphorus- and nitrogen-rich pollution. The impact of harmful algal blooms ranges from disruptive to deadly.