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March 18, 2014 | 03:09 PMWe are emerging from a winter that was sorely needed.
Throughout the state and the entire Great Lakes region of the country, the last two decades of mild winters have increased water temperatures. Higher temperatures prevent lakes from fully freezing over, and that exposed winter water has been disappearing in invisible plumes of vapor that may not ever return.
Over the past few years, the ice-blanket that has historically protected Wisconsin lakes from winter evaporation has been less effective, and for shorter periods of time. This has caused a drop in lake levels despite higher-than-average precipitation in some years.
When cool winds sweep across the state in the fall, the cold air mixes with the warm water and carries it off into the wind. And when the water does finally freeze, it has done so too late and thawed too early.
Ice helps stabilize water-levels by limiting direct sunlight and air exposure, thereby preventing winter evaporation.
This phenomenon was explained at length by the Milwaukee Journal Sentinel's Dan Egan in a July 2013 article titled "Does Lake Michigan's record low mark beginning of new era for Great lakes?"
But this year was different. It was a healthy winter for our lakes — there was a great amount of precipitation and the deep freeze helped maintain current water levels.
And because of Geneva Lake's depth, spring fishing is looking pretty good, too. During long and cold winters, shallow lakes with thick ice and snow cover can suffer from lack of sun light penetration, said Susan Beyler, the DNR's fisheries specialist for southeastern Wisconsin.
"If you've got ice and snow and the ice isn't very clear, that prevents the light penetration, and so some of our shallow lakes, or the shallower areas of some of our deep lakes, can go anoxic."
When a body of water is anoxic, its oxygen sources have been depleted. Lake ecosystems rely on the photosynthesis of plants like algae to produce oxygen. Without light, oxygen production halts and plants die and decay, which uses up pre-existing oxygen. The lakes can then become toxic for fish.
"So there is a possibility that we may see some fish kills this winter," Beyler said. "Generally we don't see those until the ice starts to come off, unless we get a really bad one and then people start to call and say, 'Well I've been drilling holes to go ice fishing and the water stinks like hydrogen sulfide', or, 'I put my minnow down and I pull it up and my minnow's dead.'"
But because Geneva Lake is so deep, one of the deepest in Wisconsin, it is unlikely to become anoxic, and in fact, has benefitted from thick ice cover and heavy snowfall. So have area streams and rivers.
"The positive is, because we've got a lot of snow, once it starts melting, our streams should be in good shape," Beyler said. "That fresh water is going to replenish the (lost) oxygen once the ice comes up and the snow melts, and it will replenish it with lots of nice fresh water, so things will be good after that."
Statewide, it's hard to say whether the positives out weigh the negatives for spring fishing, Beyler said.
"It depends on where you are and what you're looking for," she said.
Individual lakes will respond differently to the ice cover — but, generally speaking, the deeper the lake, the better the fishing; at least this year.
"It may be a little bit of a late start," Beyler said. "If you're planning to fish up north, I know that there have been opening days where there's still ice cover on the lake. And who knows, we could get two weeks worth of 70-degree days coming up in the next couple of weeks, so it's all just a guessing game."
But once things get started, she said, it could be a good year. We'll just have to wait and see.
There is one guaranteed positive to come from this winter, however — Geneva Lake hasn't lost much water.