Algae are naturally occurring unicellular microscopic plants that appear in our lakes, rivers, ponds and streams. Warm weather, sunlight and increased nutrients (phosphates and nitrates) cause algae to flourish, which explains why, in the age of climate change, we're seeing more algae earlier in the season. Typically, large amounts of algae would appear in mid- to late-summer into fall. In 2020, we've been seeing them since mid-June. While algae is a normal part of the aquatic ecosystem, offering food and shelter to some fish and other species, an excess of algae – known as a bloom – can upset the natural order of our lake environment.
Blue-green algae, aka Cyanobacteria, are another matter altogether. Identifiable by their bluish tinge, blue-green algae produce toxins that pose a risk to humans and animals. If you see a blue-green algae bloom, report it to Peterborough Public Health at 705-743-1000. Assume toxins are present. Avoid using the water for swimming or drinking and keep your pets away from the water.