Water is most dense at 39º F. When surface water reaches 39 degrees after ice-out in spring, it becomes heavier than the water immediately below it and therefore sinks. The downward movement of the surface layer forces water in the deeper parts of the lake upward. This circulation of water is called spring turnover. The April 12 mean temperature for Collegeville is 44º F. Thus, it can be assumed that spring turnover has already occurred. Note, however, that the lakes in question have already been cleared by the top experts in the nation. (Continued on next post, above)
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