Last year a deadly algae took over many water sources in Colorado. It's called blue-green algae.
It's common in Colorado in the right conditions... HOT. And it's been warm in CO lately.
Blue-green algae can be harmful especially to dogs. In 2019 there were many reports about dogs swimming in blue-green algae infested waters and dying within half an hour of entering the water.
Blue Green algae is commonly found in stagnant waters when the temperature is higher. So be careful around ponds & lakes.
This year in 2020 the blue green algae has been detected.