(C) Iowa Capital Dispatch This story was originally published by Iowa Capital Dispatch and is unaltered. . . . . . . . . . . Warmer weather at Okoboji: What it means for the lakes and those who use them • Iowa Capital Dispatch [1] ['Arnold Garson', 'Michael Bugeja', 'Douglas Burns', 'Randy Evans', 'More From Author', 'April'] Date: 2024-04-06 The changes in the lakes area resulting from warmer temperatures can be found not only in the lakes themselves but in the life and land around the lakes. Tornadoes A rare but real threat around the Iowa Great Lakes, they can be much larger and much more damaging today than they used to be. One study showed that tornado power has been increasing by more than 5% a year in recent years. Another showed that the size of a tornado increases as water temperatures increase. Skopec noted that those who monitor tornadoes are talking about creating a new F6 category because tornado wind power is beginning to go beyond the upper limits of the F5 category, which is the top category. Warmer temperatures, again, are a factor. More frequent flash floods and more droughts There are heavier, more frequent rainfalls than what used to be the norm. The floods not only cause property damage and inconvenience, they produce damaging lake shore erosion. At the same time, the increasingly long dry spells have produced more droughts, which are lowering lake levels. In East Okoboji, this is one of the factors leading to the curlyleaf pondweed invasion. Among all of these problems, the most troublesome has been what is known as the blue-green algae, even though its color looks bright green on the surface. These algae blooms are fueled both by warming water temperatures and by excessive nutrients – phosphorous and nitrogen – coming into a lake from landscaping runoff around the lake and from agricultural land draining into the lake. The bad blue-green algae tends to overtake the good algae, which produces necessary nutrients. In addition, lakeshore erosion or a bank collapse can dump nutrients into the water. Heavy rains used to be one to 1.5 inches, Skopec said. Now, we see 2-, 3- and 4-inch rains. Beneficial vegetation in the lakes gets drowned out. Water levels erode the banks and harmful nutrients rush in. All of which sets up the bad algae blooms. Overall, the least affected lake in connection with most of these water-warming issues is West Okoboji, Skopec said. It is deeper and the water at the deeper points is much colder than the water at the bottom of the shallower lakes – East Okoboji and Spirit Lake. West Lake is deeper than either of the other two by as much as 100 feet. West Lake also has more surrounding wetlands than the other lakes, thus providing some protection against adverse agricultural runoff of nutrients. “Sometimes we see the harmful algae in shallow areas or embayments, but not very often,” Skopec said, adding that the beaches of West Lake rarely have outbreaks of the harmful algae fields. Looking ahead, however, there are a couple of issues that could touch on West Lake. The fragility of both Spirit and East Lake resulting from their shallow depths, warmer water, and warmer weather could make parts of them unusable at times. East Lake also is at risk because of its history. The Indians considered it more of a marshland than a lake. Its depth was artificially maneuvered for some increase during the early years of development in the Lakes Area. With curlyleaf pondweed spreading across the bottom of the lake and longer droughts resulting in loss of water depth, could East return to its marshland status? All of this at least raises the possibility that people who live on East and Spirit might be forced to move their boating activity to West Lake. Skopec recalled that when curlyleaf pondweed made much of East Lake problematic for boating one recent year, many boaters from East Lake did move over to West. How many people can we put on West? Skopec asked. There are only so many square acres of water. Additionally, the threat of drought and lower lake levels would affect West Lake as well. Among other things, East Lake and West Lake are connected. If East loses water depth, West will lose it. It still would be a deep-water lake, but if that loss of depth becomes as much as 10 or 15 feet, how much longer would dock lengths on West Lake have to be to allow private boats to dock and be raised into hoists? Solutions to all of this? Yes, there are a few. Increasing vegetation in the lakes and harmful algae blooms can be managed to some extent with herbicides. They already are being used on curlyleaf pondweed, even though it keeps coming back. More wetlands around the lakes also would help, both in slowing agricultural runoff and the runoff during heavy rains. Can individual Lakes area residents play a role in minimizing the climate change impact on the lakes? Skopec said they can. Here’s how: Avoid fertilizers containing phosphorus “None of our soils around here need phosphorus,” Skopec said. It just runs into the lake and causes those bad algae blooms, she said. Minnesota, she noted, prohibits the use of fertilizer containing phosphorus. In Iowa, however, phosphorus is regulated by the Department of Agriculture. “I don’t think they have any interest in banning phosphorus fertilizer around lakes in Iowa,” she said. Plant deep-rooted native vegetation Planting on the banks around the lakes will help hold the banks in place even in adverse weather situations. One example is the purple cone flower, which develops 6-foot-deep roots but does not grow tall, so it will not intrude on the lake view. Consider natural landscaping Use plants instead of grass that do not require sprinkling systems and are drought tolerant. “The added benefit is all the wildlife, the bees, the butterflies, the birds, they love it, too,” Skopec said. The bottom line in all of this? Skopec put it this way: “We can manage the vegetation. We can manage the harmful algae blooms. We could try to manage the nutrients. “But we can’t change how much rain we have and how hot it is. Those things are outside our control.” Coming Sunday: The bigger picture. Why climate deniers are wrong, the global warming problem, and how Iowa is in a special position to help solve the problem. [END] --- [1] Url: https://iowacapitaldispatch.com/2024/04/06/warmer-weather-at-okoboji-what-it-means-for-the-lakes-and-those-who-use-them/ Published and (C) by Iowa Capital Dispatch Content appears here under this condition or license: Creative Commons CC BY-ND-NC 4.0. via Magical.Fish Gopher News Feeds: gopher://magical.fish/1/feeds/news/iowacapitaldispatch/