If you can, check the depth at the dam. You can use a fishing rod with a heavy weight and a slip bobber. If the weight sinks the bobber, move the slip knot higher until the bobber floats. Measure that distance. If there is a large descrepancy, that would (might) give you an idea of how much silt is in the pond.

Does the dam have a metal pipe going thru it? If so, check it's condition. If it hasn't been replaced since the pond was built, double check it for rust/corrosion/leaks. Rex had a good idea of having a plumbing contractor that has a camera inspect the inside of the pipe. To repair a bad pipe, it might be necessary to drain the pond.......

When I bought this place I was told the pond was 15' deep. The first year I had a massive fish kill and when I measured it was actually only 6'-7' deep. If I had known that, I would have installed an aerator and avoided killing 5#-6# LMB, 24"+ CC and lots of large BG.

If the pond isn't what it's advertised to be, and it's a selling point of the property, it would be a bargaining chip in your pocket. (it'd cost XXX to make it the way it's advertised)

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).