Merritts, Walter & Fleming: Generations of sediment choking Chesapeake Bay

Near the geographic center of the Chesapeake Bay Watershed, a narrow creek winds through a small rural Pennsylvania valley. Here, in the early 1700s, settlers built a dam that unwittingly damaged one of nature’s best water pollution filters — valley bottom wetlands — ushering in an era of water quality decline throughout the region. The 20-foot dam powered a grist mill and formed a pond extending more than a mile upstream, large and deep enough (as much as 20 feet) for people to boat, fish, skate or swim.