There are numerous examples in Wisconsin and elsewhere that show that Eurasian water milfoil can be substantially reduced for multiple years following an overwinter drawdown if the exposed lake bottom freezes. Preliminary laboratory testing with starry stonewort has shown that freezing, even for short periods of time, will kill the star shaped bulbils that allow for plant regrowth.
In addition, the exposure of lake bottom sediments to dry and freezing conditions can cause the organic sediment in the exposed lakebed to compact and oxidize; increasing the water depth following the drawdown. This oxidation can lead to increased release of phosphorus from exposed sediments initially after the lake is refilled, but less phosphorus release after the initial flush from refill.
The extent of control of EWM and SSW and compaction of lake sediments will depend on the severity of the two winters and the amount of drawdown that is possible. Colder and dryer fall and winter weather will create conditions for better control of these invasive plants and organic sediments. Cracking sediment on the exposed lakebed is a sign that the lake bottom has dried enough to allow compaction of organic sediments and plant seed germination. The exposed sediments will be checked in winter to determine the depth of frost and freezing conditions.