The use of land within watersheds is a basic factor in understanding the ecological condition of the Mid-Atlantic estuaries. Note that the Delaware Estuary watershed is the most urbanized and that the land cover distribution in the Delmarva coastal bays is distinctly different from the rest of the region. Forests are important because trees filter sediment and nutrients from runoff, and their roots stabilize the shoreline and reduce erosion. They also shade the water, reducing summer water temperatures. In some parts of the region, forests are rapidly being replaced by agricultural and urban lands.
Agricultural land comprises two groupings pasture and cropland.
Pasture land consists of grassy areas for raising and feeding livestock. Cropland is cultivated to provide various food products. Approximately one-third of the land in the region is agricultural. As a watershed becomes more developed, the amount of pollutants carried in the storm water increases, as does the amount of wastewater and solid waste requiring disposal. The storm water flows in urban and developing areas also cause habitat damage and destruction.