If there is no water going into your pond during the winter from rain, snow or from the well, and it doesn't freeze over, then yes, it will keep evaporating. Our Lake effect snow storms come from water that's evaporated from Lake Michigan.

But, when have you had a winter without snow or rain? Mine is a ground water pond, and it's level has dropped even after it has iced over. It has always filled back up in the Spring due to rain or snowmelt.

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