Water leaves a pond 3 ways: leak, evaporation, and capillary action. Evaporative rates for NE or MO this time of year is less than .1”. Capillary action is real, but generally accounts for about half of evaporative rate. Anything beyond that I attribute to seepage. I’ve spoken to Joe back in late Summer - assume he’s still experiencing some issues. Best method to determine is by measuring vertical water loss using a ruler, etc.