Hi there,
Im in Zeeland/Holland West Michigan.
I have one pond, formerly 2 but they were connected 10 years ago and a spancrete bridge put over them.

They were dug in ~1990 by my dad with a large excavator. The spoils were used to make the banks.
Around 2000 the ponds were connected and a spancrete bridge placed over them.
We have 5 diffusers run off a 1hp pump to aerate the pond.
The ponds were originally ~12' deep at the deep end but have since filled with muck. I am not sure if its from dead organics or banks deteriorating from muskrats.
A few weeks ago I used a small excavator to remove the muck from about 500' of shoreline and will probably do the entire pond this coming 4th of July. You can see the pile of muck in the picture to the right of the grey pump house.
The pond has tons of large and small mouth bass, bluegill, sunfish and at one point Walleye (but no one has caught one in a while).
I have around 20 acreas of property, the pond is just under 2 acres

I will totally buy the sonar off you, just have to figure out how much I need.