Well...I've been clearing the vegetation and trees around the area, so I can get the hoe back there, and have made a few observations.
1) Having gotten further into the leak (looking in from the opening, I have not opened the top yet) it is extensive, running right and left from the opening and larger than I had anticipated, a good cubic yard or two of missing earth at least.
Going to have to scout that out some more before I put a machine back there.
2) There is a tile system of some sort involved in the problem. As the pond has dropped lower I have found a tile opening below the old water level that is packed with dirt. This is about five feet to the left of the leak. Judging by the angle it runs right into or under the area where the water is dropping down into the bank. And I can see tile pieces in the large opening mentioned in 1. Need to get down in the creek and look at the opening on that end to confirm, but I was always pretty sure that was a tile too.
3) I found a tile on the opposite bank that is supplying some incoming water to the pond.
4) As the pond level has dropped it is quite obvious that the old depth of the pond has been largely filled with organic muck at least towards the banks - suspect there is one small area of depth left in the middle.
That is the update...thinking more about draining it...and wondering how I will deal with the incoming water from the tile if I do decide to drain it.
