How to deal with a pond silting up
That is what lakes and ponds do , fill with silt. Serious earth moving equipment is needed to slow Mother Nature. Our community has recently removed some silt with draglines, bulldozers , trucks , etc. I don't know the cost but certainly significant . They concentrated on certain areas to facilitate flow as we have a dammed stream that made roughly a 300 and 100 acre lake and the costs of general silt removal would be overwhelming.  On the upside , bushes on a new island have become a egret rookery,