The one article mentions the research being done at Franklin & Marshall College on "Legacy Sediments". I was fortunate enough to spend several years conducting research with Merritts and Walter. Several years ago, they were able to use very conservative estimates and show that theoretically all of the sediment coming from the Conestoga River Watershed comes from the stream banks. There is a lot of stream bank sediment that accumulates in the stream and takes years to be washed into the Susquehanna River. Certainly this is not the only source of sediment going into the River and Bay; however, conservative estimates are that stream bank erosion accounts for 70-80% of the total sediment load (at least from Lancaster and York Counties where much of the sediment comes from). This information has been available for several years now, but most floodplain "restoration" projects neglect to use this science during the planning stages. The major hinderance is the substantial cost of removing the sediment. Natural Stream Channel Design only puts a bandage on the problem, and unfortunately I have seen it fail in many places and subsequent improvement projects have been done over existing restoration sites. The cost of removing "Legacy Sediment" is great, but what most people do not realize is that Pennsylvania is going to be fined upwards of $15 billion within the next two decades if we do not significantly reduce our sediment load to the Chesapeake Bay. The original date was supposed to be in 2015, but I believe it has been pushed back. We might as well use those billions of dollars to fix our problem rather than wash it down stream with the sediment. Pay now or pay later. At least if we pay now we will get something in return.
