I'm no expert on lakes
but I do believe the lake was a man-made sport fishing feature, along with the fish holding area (the area that Potts wants to be the natural swimming pond). They diverted water to create it (centuries ago) from the local streams and it has a built-in sluice (?) feature to lower the lake (control the water level), when fish would be moved to the holding area (natural swimming pond to be) perhaps for breeding or restocking. Not sure how the lake is or was connected to the moat, if at all. The moat also used to be larger and was changed at some point, but they discovered original walls. Not sure about the water table or well system of the property but there are some natural streams that seem to run through the property. I can't recall any video where Stephoney talked in-depth or knowledgeably about water on the property (lake, natural natural streams, water table, wells and natural water sources). Her "narrative" was that water police demanded she drain the lake and threatened her with fines and legal troubles, so she did so without talking to any experts (being all alone and depressed, she didn't bother to investigate or hire an expert at that time - insert sob story here) -- so she opened the sluice (?) and drained the man-made lake. She found out some years later that the water police lied to her or misled her -- I recall her saying that she could have chosen NOT to drain the lake, but once she did so, they could then threaten her with legal troubles if she refilled it (using local water). I do know that Europe has complicated rules around water for conservation. In the meantime, trees and shrubs have filled the area -- and I believe there's still some swamp area where the frogs and other creatures have made their home. We'd need a good topical map to see the water systems clearly which I suspect that now have with the various surveys.