Thanks for the feedback. I understand your comment about the "babbling brook" coming off a hill. There is some water that comes from a slough on the inlet side that has a steady flow but I'm not sure if its enough to oxygenate the water. I'd guess much of the lake is being refilled by seeping springs from the shore or from the bottom of the pond. The DO then must be coming from some remaining algae. At any rate it's apparently present which does answer part of my question.
Your comment about removing smaller fish brings me to another question I haven't explored yet... how many of a given species can I harvest without negatively impacting reproduction? I haven't explored this yet and am sure there are many references that help answer that question. I have defaulted for the time being to returning all of the game fish BG, YP, LMB to the pond for being unsure of affecting the breeding population. I'm open to removing some as I gain confidence that I'm not going to mess the balance up somehow.
Regarding the hyporheic theory... I'll have to look through your link to understand more. My first impression is that the pond is higher in elevation than the river (SWAG +10' maybe) so that should create an outflow of water from the pond to the river rather than the reverse. The river is perhaps 1/4 mile at it's closest spot.
Thanks for the insight on the excavation. There already is a 6" layer of black muck across much of the basin that I've been wondering if is a problem. I wouldn't want all of that to end up in the 12' excavation. More to ponder.
BTW... the weird ring/rash around the gill plates of the NP is where he stuck his head in my trap & got caught, I did end up eating him since he was just about done for.
