- Jan 13, 2005
We usually see (green) algae on our local waterways when the temperature reaches around 100, but nobody gets too worried about it, because it disappears as the temperature drops. A few years ago we started seeing blue-green algae (cyanobacteria), which is toxic to humans and pets. We were recently notified that it's back in our Delta waterways. Chris had been enjoying evening swims with one of the doggies, but has quit in the interests of health and safety. I've heard that it's also shown up on several lakes in several states.