Since colonial times, no change to the Chesapeake ecosystem has been greater than the alteration of its landscape. A vast expanse of forest once absorbed most of the rainfall and held most of the sediment in place.
Over time, the forests have been replaced with farms and development, all of which have greatly increased the amount of runoff and pollution reaching streams and the Chesapeake Bay. While forests still comprise the greatest land use in the region, they have been greatly altered, consisting of smaller trees and lacking many of the species — such as American chestnut — that were common in the past.
The rapid rate of development in recent decades has accelerated the spread of impervious surfaces such as roads, roofs and parking lots, dramatically increasing runoff and degrading stream health throughout the region. Conservation efforts are underway to identify, and protect, some of the high priority landscapes and resources that remain.