Forests and wetlands tend to act as filters or sponges, absorbing rainwater—and NPS pollution—before it reaches the river and bay. Paved, or developed land does not absorb rainwater, but funnels runoff, and the pollutants it carries, directly into streams before it can be filtered through the soil and plants.
Sediments have also created new shoals and mud flats and filled many streams and channels. For example, Mauricetown was formerly a deep-water port for ocean-going ships; however, few of those ships could get there today. Other ports, and indeed the main river-bay channel, need frequent dredging to keep them open. This dredging can cause sediment and other contaminants that have already settled out to be resuspended in the water, exposing oysters and other animals to the recycled pollution. Undredged ports lose their access to trade and often become ghost towns.
So, filling a wetland in South Jersey, or cutting down a forest as far away as the Catskill Mountains of New York, can endanger the health of oysters in the Delaware Bay—as well as jobs along the rivers. Use of proper erosion-control measures (silt fences or straw bales, keeping livestock away from streams, letting lawns grow longer, or planting native plants instead of exotics) when excavating or planting, and careful use of water (applying as much water as plants can use) can often reduce sediment runoff significantly, helping to protect those oysters and those jobs.