Rough Day on the Lake

It was a rough day on Lake Winnebago recently.  Steady winds at 30 mph and gusts to 50 mph were driving large waves on the lake.  Lake Winnebago is no pond, but it is not one of the Great Lakes or the ocean, so the waves are not monumental, but I would not want to be out in a boat on day like today.  On huge bodies of water the wave heights can be immense, but on a shallow lake like Winnebago the wave lengths are short, meaning a boat, or the shore is repeatedly pounded by waves in short succession.  There is no riding the waves up and down in this situations, just a constant battering.  The waves are continually interacting with the bottom, disturbing the it in deeper water and churning it into a soup in the shallows.

This churning of shallow waters, and erosion of the shoreline, releases nutrients from the bottom where they can be taken up by algae.  If warm, calm weather with bright sunshine were to follow a storm such as this an algae bloom would not be far behind.  This time of year though an algae bloom will be less noticeable because it will be dominated by species of diatoms sometimes called the golden brown algae.  When diatoms bloom they can be mistaken for sediment.  In the summer Lake Winnebago would be dominated by blue-green algae.

High winds also drive water across a body of water stacking it up on one side.  On October 14th when the video was taken NE winds caused a half a foot difference in lake levels according to the gauges monitored by the US Army Corps of Engineers.  These changes in water levels brought on by wind events can give lake users a sense that the entire lake has rapidly changed water level, when the effect has only been local.   When the wind abruptly ceases it will cause a sloshing effect, as if the lake were a huge bathtub.   This sloshing is called a seiche.

Click the pdf. below and look at the bottom graph to see the differences in water levels on the four Lake Winnebago gauges

Lake Winnebago Water Levels

The above was generated by the USACE Lake Winnebago Information website.

 

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