​The same wetlands and springs that we enjoy are what keep our lake levels relatively stable.  Do they change at all from year to year?  Certainly, but even with a very dry summer the wetlands, (think “sponge”) supply enough to keep levels within the normal range.  The same would not be possible at Crystal Lake.  The other variable are dams. Over the years several studies have been undertaken to see if the dams, one on the Little Betsie, one on the shoreline of Duck Lake and the other below Green Lake at the Grass Lake recreation area, had any affect on the level of Green Lake.  The number of boards in or out of the dams, year around and readings taken at the Betsie River outlet on the lake were logged and the impact, if any, was noted.  The clear conclusion was that the effect of lowering Duck Lake in the fall had almost no impact on the level of Green Lake after a couple of days.  The same was true when the boards were replaced in the spring.  Green Lake didn’t drop as the wetlands gave up water to keep the flow rate the same.  The Grass Lake dam had no impact as it is too low to raise the lake level if the boards are put in and has a fixed spillway to handle any high volume of water.  The bottom line is neither dam has any significant effect on Green Lake water levels.  The Duck Lake dam does control the level of that lake as it was designed to do.  837.3 feet was set by court order but an unofficial compromise has worked pretty well by lowering the level in the fall to avoid ice damage and raising it in the spring for the boating and peninsula canal needs.  The dams and their impact on lake levels appear to be one of those rare occurrences where  Mother Nature has forgiven us for getting into her business! Click here for the complete 46 page Betsie River Watershed Hydrologic Study performed by Michigan Department of Environmental Quality in 2014.