Native Americans lived in the Delaware River Valley long before its "discovery" by European explorers. You can learn more about the region's native populations at https://native-land.ca/.

In 1609, Henry Hudson first sailed into the Delaware Bay, and the region began to be colonized a few decades later. The river basin was a major part of the American Revolution and played a key role in defining and shaping the fledgling nation.

Pollution in the Delaware River, particularly in the tidal reaches of its urban centers, began to be a recognized problem by the early eighteenth century and continued to be a serious issue over the next 200 years, mostly due to rapid population growth and increased industrial activities. Severe pollution was most evident by the prevalence of waterborne illnesses and in the sharp decline of migratory fish populations, such as the American shad.

By the height of World War II, the tidal Delaware River was largely considered an open sewer for public and industrial waste, and pollution was rampant. The river's water was so foul that it would turn the paint of ships brown as they traveled through or were docked for any period of time. People were sickened by simply the smell of the river. Additionally, there were parts of the estuary that were considered dead zones, almost or completely devoid of oxygen needed for the survival of fish and other aquatic life.

Delaware Estuary Dissolved Oxygen: Historical Problems & Recovery

An early, important task of the Delaware River Basin Commission (DRBC), a federal-interstate agency created in October 1961, was to work on cleaning up the polluted waters of the nationally significant Delaware River. In 1967, it adopted the most comprehensive water quality standards of any interstate river basin in the nation, which also included bacterial standards for primary and secondary contact recreation, i.e., swimming and boating, respectively. The standards were tied to an innovative waste load allocation program which factored in the waste assimilative capacity of the tidal Delaware River (the predecessor to today's "Total Maximum Daily Loads").

A year later in 1968, the DRBC adopted regulations (pdf 4 MB) for implementing and enforcing the standards. The Federal Water Pollution Control Act Amendments of 1972, commonly referred to as the Clean Water Act, further assisted the implementation of water pollution control efforts in the basin, as did state-led efforts. Funds for constructing municipal and wastewater treatment facilities were also provided by government partners.

By the late 1980s, over one billion dollars had been spent on improving wastewater treatment facilities in the Delaware River Basin, which benefited human communities along the river and strengthened fish populations. DRBC began its Delaware Estuary Toxics Management Program in 1989, designed to develop methods to control the discharge of toxic pollution from wastewater treatment plants into the estuary. New rules were adopted in 1996 stemming from the Estuary Toxics Management Program that added many toxic substances to what was originally regulated in wastewater treatment plant discharge. DRBC’s toxics criteria was most recently updated in 2010.

While intensive efforts were underway to clean up the tidal river to meet standards, monitoring demonstrated that the water quality in the non-tidal Delaware was already better than standards. DRBC in 1992 launched the Special Protection Waters (SPW) program, which established regulations to "keep the clean water clean" in the upper and middle sections of the non-tidal Delaware, portions of which had been designated by the federal government as part of the National Wild and Scenic Rivers System in 1978. Following the federal designation of an additional 38.9 miles of the Delaware in the National Wild and Scenic Rivers System in 2000, DRBC in 2008 expanded SPW coverage to include the river from the Delaware Water Gap National Recreation Area downstream to the head of tide at Trenton, N.J. The entire 197-mile non-tidal river is now included under the SPW regulations, which is believed to be the longest stretch of anti-degradation policy established on any river in the nation.

Today, the clean-up of the Delaware is hailed as one of the world's top water quality success stories. The river now supports year-round fish populations, as well as those returning to their natal waters to spawn. Bald eagles, which depend on fish as their primary food source, reside and nest throughout the basin from the river's New York headwaters to the Delaware Bay. Pleasure craft marinas line waterfronts once visited only by commercial vessels, and river-based recreation is one of the region's top economic sources. The river and many of its tributaries are flanked by attractive greenways and parks. Officially designated water trails exist for the non-tidal and a portion of the tidal Delaware River, as well as Pennsylvania's Lehigh and Schuylkill rivers, the two largest tributaries to the Delaware.

These improvements, as well as other DRBC accomplishments, over the past fifty+ years are rooted in the Delaware River Basin Compact's chief canon: that the waters and related resources of the basin are regional assets vested with local, state, and national interests that all share joint responsibility to maintain and protect.

However, it is important to note that the work is far from complete, as parts of the river still are not "fishable and swimmable," which is the stated goal of the federal Clean Water Act. New technology enhances the DRBC's ability to detect, monitor, track, and model pollution such as PCBs in the river. The commission's policies, programs, and abatement efforts must therefore adapt and evolve in order to continually improve the basin’s water quality for future generations.

Related Articles:

• "The Historical Context of Water Quality Management for the Delaware Estuary" by Richard C. Albert (1988; pdf)
  
  
• "The Delaware River Revival: Four Centuries of Historic Water Quality Change from Henry Hudson to Benjamin Franklin to JFK" by Gerald J. Kauffman, Jr. (2010; pdf)