A biologist with the Iowa Department of Natural Resources says Iowa’s fourth largest natural lake went through a number of changes this past year. Ben Wallace says last spring the water in Storm Lake was exceptionally clear.

“It looked pristine, to be honest with you, but about midway through the summer we got a pretty strong cyanobacteria bloom,” he says. “Cyanobacteria is also called blue-green algae.”

The water in Storm Lake was green for several weeks, according to Wallace.

“Once you get something started like an event like a cyanobacteria bloom which creates their really turbid water, it’s hard to break away from that and get back to that clear water state,” Wallace says, “but fortunately in the Midwest we have pretty normal winters where ice sets in and kind of resets everything, so it will be interesting to see what next year brings.”

Wallace says the water levels in Storm Lake were lower due to the drought and that exacerbated algae growth.

“When you look at a lake like Storm Lake or Black Hawk Lake or any of our surrounding natural lakes, oftentimes you might have about 40% of the entire lake’s water volume in that top two feet” he says, “so if you lose two feet off your lake through evaporation — just dry periods — you’ve lost a very significant portion of the volume in your lake, so you can imagine how that would concentrate nutrients.”

Wallace made his comments during a presentation to the Storm Lake City Council.