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4.2. Karth Lake water level modeling and management process progress report. <br />Renée Marino <br />4.2.1 Background: Hypothesis: a revision to the pump management policy can <br />reduce water level bounce (i.e., range of high and low levels), which can improve <br />lake quality and its environment while appropriately mitigating risk of damage to <br />shoreline properties. <br />Discussion: Renee presented charts showing preliminary application of lake level <br />hydrology model to recent lake level data (attached). Here are some observations: <br /> <br />The model’s current inputs include month, daily rain amounts and pump status. <br />Renee extended the model from a single period to 30 days. <br /> <br />Rain data from Linda’s internet-connected gauge is fair but not perfect. For <br />example, there was one time when the lake went up but there was no recorded <br />rain. <br /> <br />Air temperature matters. For example, the lake level dropped faster than the <br />model’s prediction for September 2023. Since that was a hot month, she found <br />that the predicted evaporation rate for August was a much better fit. <br /> <br />The spread of rain throughout the month also matters. The model assumes that the <br />first inch or so of watershed rain will be absorbed by the soil and the excess will <br />run off into the lake. In one week when there was a small quantity of rain each <br />day, the model predicted no change but the actual lake level rose. Conversely, <br />when there was a large single day of rain in September, the model over-predicted <br />the rise in lake level. <br /> <br />The purpose of this project and the model is, of course, not to provide a perfect <br />forecast of lake levels but, rather, to investigate the impact of pumping strategies <br />in a flooding type of scenario. Karth Lake reached its highest recorded levels in <br />2002, so that year’s rain pattern should be a test case for evaluating alternative <br />pumping strategies. A comparison of the 2023 rain pattern to 2002 daily rain data <br />from NOAA is: total rain in 2023 was about 1.5 feet versus 2.75 feet in 2002. The <br />maximum rain event in 2023 was around 0.4 feet in September versus two events <br />(June and September) of 0.5 feet in 2002. <br /> <br />Renee plans to do a couple of further steps before reviewing the model with its <br />developers at RCWD and Houston Engineering. There followed a general <br />discussion of this project’s history and goals. <br /> <br />4.3. Bylaws review and possible modification. Susan Johnson (not in attendance) <br />4.3.1 Background: A preliminary review of the bylaws questions who is a <br />member of KLID, how elections should be run going forward and who can vote. <br />Discussion: This topic is on hold. Susan asked Renee to report that she plans to <br />follow up with Arden Hills’ counsel on this topic since she has not heard back