It looks like you hit groundwater like I did when digging the pond. If this is where you want to put the dam, then you might have to revise your plans. If the guy that's digging your pond is an experineced pond builder, then I'd go with his recommendations. If not, then I'd try and do some long distance troubleshooting with Mike Otto.

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).