I’d have to agree, although this particular area is completely within my neighbors property. They own the land on both sides of the stream, as do I just downstream from there. This area didn’t just fill in with silt, there were some major flooding events that did the majority of the filling in, especially Floyd (I think that was the one). Tons of rock and gravel were deposited in there from the gravel road which runs by the stream. I’d think the carting away and disposal of the mud would be the most significant part of the cost.
You can see the erstwhile swimming hole in this google map image circled in black. When the stream floods, all the gravel from the road circled in blue gets carried into the pond.