Robinson, I have not been able to read all the threads, and just now got the jist of this one. I really feel badly for your situation. I know this past summer you had high hopes for the new lake.
To expand on Ric's good suggestion of the dye, maybe instead of puncturing the bags, if they are placed close to the suspected leak, it would surely get broken as it is sucked down and through wherever it is going.
Best of luck
