Delaware River Basin Overview

Delaware River Basin Overview#

The Delaware River Basin (DRB) spans four states (New York, Pennsylvania, New Jersey, and Delaware) covering approximately 35,000 km² and supplying water to over 14 million people. The basin supports diverse water uses including ecosystems, agriculture, recreation, transportation, mining, and hydroelectric generation.

Key Infrastructure & Operations The Delaware River mainstem remains the longest undammed river east of the Mississippi, but multiple tributary reservoirs significantly influence basin hydrology. Three NYC-owned reservoirs in the upper basin (Cannonsville, Pepacton, and Neversink) provide 1,030 MCM of aggregate storage and enable major transbasin diversions—up to 3.0 MCM/day to NYC and 0.45 MCM/day to New Jersey. Additional reservoirs are operated by USACE, private companies, and state agencies for water supply, flood control, hydropower, and recreation.

Institutional Regulatory & Management Framework Basin management operates through a complex multi-jurisdictional system rooted in Supreme Court Decrees (1931, 1954) that established diversion limits and downstream flow targets. The Delaware River Basin Commission (DRBC), formed in 1961 through interstate-federal compact, provides comprehensive basin-wide governance with representatives from the four states, NYC, and federal government. The Office of the Delaware River Master (ODRM) monitors and enforces decree provisions. Emergency drought modifications require unanimous consent among all parties, necessitating careful balance of diverse stakeholder interests across the basin.

The complex water management infrastructure and multi-jurisdictional governance described above create significant impacts on hydrologic dynamics throughout the basin.

The resources below are meant to serve as a starting point for anyone interested in learning about the DRB. The links below will redirect you to DRBC, USGS or other external webpages relevant for the basin.

For more comprehensive information regarding water resources management in the DRB, and representation of management within the Pywr-DRB model, see the referenced literature in the Reading List.

Delaware River Basin Commission Resources#

The links below provide access to resources developed and maintained by the DRBC. To further explore the DRBC resources, see DRBC website: www.nj.gov/drbc/

U.S. Geological Survey Resources#

The U.S. Geological Survey (USGS) has conducted several scientific studies within the DRB as part of their Regional Water Availability Assessment activites. You can read more about the motiviation, ongoing work, and outcomes of this science using the links below.

Regulatory and Policy Documents#

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