The Corps Water Management System (CWMS) includes four interrelated models to assist with water management for the basin:

- GeoHMS (Geospatial Hydrologic Modeling Extension)
- ResSIM (Reservoir System Simulation)
- RAS (River Analysis System)
- FIA (Flood Impact Analysis)

The Delaware River is the longest un-dammed river east of the Mississippi River, extending 330 miles from the Catskill Mountains in New York to the mouth of the Delaware Bay where it flows into the Atlantic Ocean. The river is fed by 216 substantial tributaries, the largest of which are the Schuylkill and Lehigh Rivers in Pennsylvania. The watershed drains four-tenths of one percent of the total continental U.S. land area. In all, the basin contains 13,539 square miles draining the four states of New York, Pennsylvania, New Jersey, and Delaware.

Parts of five physiographic provinces lie within the Delaware River Basin. These are the Coastal Plain, Piedmont, New England, Valley and Ridge, and Appalachian Plateaus. Topography varies from the relatively flat Coastal Plain, which consists of unconsolidated sediments, to rolling lowlands and a series of broad uplands in the Piedmont. North of the Piedmont Province, the New England and the Valley and Ridge Provinces consist of rock layers that have been deformed into a series of steep ridges and parallel folds that trend northeast-southwest. The Appalachian Plateaus occupy the upper one-third of the basin and are characterized by rugged hills with intricately dissected plateaus and broad ridges. Altitude in the basin increases from sea level in the south to more than 4,000 feet in the north. During the last major glacial advance, the Appalachian Plateaus and parts of the Valley and Ridge and the New England Provinces were glaciated. North of the line of glaciation, valleys typically are underlain by thick layers of stratified drift and till.

Average annual precipitation ranges from 42 inches in southern New Jersey to about 50 inches in the Catskill Mountains of southern New York; annual snowfall ranges from 13 inches in southern New Jersey to about 80 inches in the Catskill Mountains. Generally, precipitation is evenly distributed throughout the year. Annual average temperatures range from 56 degrees Fahrenheit in Southern New Jersey to 45 degrees Fahrenheit in Southern New York.

Approximately five percent of the nation’s population (15 million people) relies on the waters of the Delaware River Basin for drinking and industrial use. The Catskill Mountain Region in the upper basin provides New York City (NYC) with a high quality source of water from three basin reservoirs, Cannonsville, Pepacton, and Neversink. Nearly half of its municipal water supply comes from these reservoirs that is diverted from the Delaware River Watershed. Within the basin, the river supplies drinking water to much of the Philadelphia metropolitan area and major portions of New Jersey, both within and outside of the basin.

From the Delaware River’s headwater in New York to the Delaware Estuary and Bay, the river also serves as an ecological and recreational resource. Over the past half century, as a result of the maintenance of minimum flow targets at Montague and Trenton, NJ, cold-water fisheries have been established in the East Branch Delaware, West Branch Delaware, Nerversink River and the upper main-stem Delaware River. Most of the main-stem upstream of Trenton, NJ has been designated by Congress as part of the Federal Wild and Scenic River System.

There are numerous economic benefits from the river. The Delaware River Port Complex (including docking facilities in Pennsylvania, New Jersey, and Delaware) is the largest freshwater port in the world. According to testimony submitted to a U.S. House of Representatives subcommittee in 2005, the port complex generates $19 billion in annual economic activity. It is one of only 14 strategic ports in the nation transporting military supplies and equipment by vessel to support troops overseas. The Delaware River and Bay is home to the third largest petrochemical port, as well as five of the largest east coast refineries. Nearly 42 million gallons of crude oil are moved on the Delaware River on a daily basis. There are approximately 3,000 deep draft vessel arrivals each year and it is the largest receiving port in the United States for Very Large Crude Carriers (tank ships greater than 125,000 deadweight tons). It is the largest North American port for steel, paper, and meat imports as well as the largest importer of cocoa beans and fruit on the east coast.