Threats to The River
Today the greatest pollution of the River comes during storm events. The rainwater washes sediments and pollution from land surfaces into streams and storm water drains. This runoff flows tainted through countless tributaries into the Delaware River. Some runoff sources are herbicide drenched lawns; oil stained streets and parking lots; fertilized farm fields sprayed with pesticides and fortified with fertilizers; and acid mine drainage.
Another hazard to the health of the River comes from point-source pollution -- direct discharges from municipal and industrial sewage treatment plants, power plants, chemical plants, paper mills, refineries, and refracteries. Most point-source dischargers have permits issued under the Clean Water Act and the National Pollution Discharge Elimination System. These permits limit the quantities and types of pollutants permitted to be contained in the wastewater. There are 1600 permitted discharge points in the Delaware Watershed.
In many urban regions of the watershed, storm water, sewage, and industrial wastes all flow through the same system of pipes into treatment facilities. During storm events the rainwater mixes with the sewage. In many cases this overwhelms the capacity of treatment facilities, which were not designed to handle the volume. Overflow devices, called combined sewer overflow (CSO), divert the excess directly into streams. An uncontrolled source of untreated sewage, CSOs are detrimental to the water quality and pose a public health threat to recreational users of the River.
As a result of this myriad of pollutants that wind-up in the River, its fish and shellfish are contaminated with toxins, including: PCBs, chlordane, mercury, dioxin and DDT. Fish contaminated with toxics pose numerous hazards for humans. Delaware River states have all issued fish advisories recommending limited or no consumption of contaminated species. The state warnings contain some inconsistencies. Fish considered unsafe on the NJ side of the river may be considered safe on the PA side of the river. These inconsistencies led Riverkeeper to create a comprehensive Toxic Fish Alert with information gathered from Pennsylvania, New Jersey, and Delaware. The alert lists all warnings and advisories issued on both sides of the river.
Toxics are hazardous to birds of prey, such as the osprey and the peregrine falcon. These birds are high on the food chain so the are especially susceptible to the effects of biomagnification of toxics. Toxics such as DDT are believed to be responsible for the thinning of eggshells, causing lower productivity for many species of birds that are already endangered. The long banned pesticide DDT is still in the River's sediments. During dredging, or tidal periods the sediments are disturbed, and the concentrated toxics are resuspended, making them more available for uptake by aquatic organisms.
The Delaware has suffered a great many losses. It once knew sturgeon by the hundreds of thousands, unabating oyster harvests, shad, terrapins, and great flocks of waterfowl. While today nutrient pollution has been greatly reduced, the River continues to face threats of pollution and habitat degradation caused by our way of life.
Prepared by Kim Appleby, Spring 1995
