Well the leak has to be in the portion that's seen water so you know where to start.. Does it stop dropping at a certain height if so the leak is above that.. Do you see any wet spots down stream or on the backside of the dam? 6-10 of drop could be possible if its not a big bod of water yet.. Post some pics of how much water you've got in it so far.. Are you sure it's dropping that much or just a estimate.. Place a measuring stick in the water mark the water level and see what happens over a week with no rain..

I believe in catch and release. I catch then release to the grease..

BG. CSBG. LMB. HSB. RES.

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