S Bengi wrote:How deep was the pond originallty, and how deep is it now? Can you ask the neighbors or prior owners kids/etc how deep it used to be? Why exactly do you want to dredge it?
Agreed! These are important questions to answer.
What is the subsoil in your area? If this was a constructed pond, digging too deep into the layer that holds the water would be a disaster.
If this an old, healthy, bioactive pond, note that any dredgings are magnificent additions to gardens, orchards, compost.