Identifying Opportunities for Climate Adaptation in the Delaware Estuary

Created: 10/28/2010 - Updated: 3/02/2020


The Delaware Estuary has a nearly continuous fringe of diverse types of tidal marshes, which serve as critical habitat for fish and wildlife and provide important services for residents in the surrounding area. Much of this habitat is presently stressed by human alterations and activities and climate change impacts appear to be exacerbating these issues. The Partnership for the Delaware Estuary (PDE), through a grant from the U.S. Environmental Protection Agency’s (EPA) Climate Ready Estuaries Program, is working to assess the vulnerabilities of tidal wetlands and two other  key  resources (drinking water and bivalve shellfish), identify monitoring and management needs, and create an adaptation plan. Lessons learned from this pilot project are expected to inform the public and managers on how to get the best environmental return on investments designed to sustain vital resources. The pilot project will also lay the basis for potential expansion of the approach to cover other natural resources.


The Delaware Estuary, spanning Delaware, Pennsylvania, and New Jersey, provides critical habitat for fish and wildlife, and drinking water, recreation, and food for residents. In addition, the estuary hosts the largest freshwater port in the world and five of the largest refineries on the east coast of the United States.

In 2008, PDE was selected as one of the six pilot projects under the EPA’s Climate Ready Estuaries Program. PDE is working with partners to examine three case studies focused on human impacts (drinking water), habitat (tidal wetlands), and living resources (shellfish) in order to assess the resources’ vulnerability to climate change. Impacts of particular concern are sea level rise, salinity rise, increases in temperature, altered rainfall, and increased storms. The three resources were selected because of their ecological and societal importance to the region:

  1. The estuary and surrounding watersheds provide potable drinking water for over 16 million people in the region. The availability of clean drinking water in the face of climate change impacts is threatened by increased salinity because many of the water intakes are from the tidal freshwater area; compounding factors include population growth, development, and alterations to freshwater flow. Project leads are investigating potential vulnerabilities to drinking water supplies in the area.
  2. Tidal wetlands play an important role throughout the estuary as habitat and regulators of water quality and flooding events. This habitat is presently degraded and is further threatened by sea level rise, salinity, temperature, sedimentation, freshwater input, and flooding. This project aims to analyze these impacts in order to quantify and value the ecosystem services that tidal marshes provide.  Potential adaptation tactics will also be contrasted.
  3. Bivalve shellfish are at risk in the estuary and its watershed. Scientists are researching and modeling vulnerabilities to different both freshwater and marine species and will compare potential adaptation options. Shellfish are commercially and ecologically viable in the region and are threatened by increased salinity, decreased water quality, warmer temperatures, disease, and non-native and invasive species introductions, among other factors.


The Partnership for the Delaware Estuary (PDE) received two grants from the U.S. Environmental Protection Agency’s Climate Ready Estuaries Program in 2008 and 2009 to support these efforts. PDE has many collaborators on this project, including the Academy of Natural Sciences, Delaware River Basin Commission, U.S. Geological Survey, and the EPA. A Climate Adaptation Work Group was also set up to oversee technical elements of the project.

For each of the three resources – drinking water, tidal wetlands, and shellfish – project leads are conducting an inventory of project climate change impacts, identifying data gaps, and identifying and prioritizing management options.

Outcomes and Conclusions

PDE expects to complete a draft adaptation report that will summarize vulnerabilities, research and monitoring needs, and potential management actions for the three resource case studies. Contingent on funding, this project may be expanded to examine other ecosystem goods and services in the estuary as well as to prepare more detailed site-specific recommendations for the three case studies.


Information gathered from interviews and online resources. Last updated 10/28/2010.


Gregg, R. M. (2010). Identifying Opportunities for Climate Adaptation in the Delaware Estuary [Case study on a project of the Partnership for the Delaware Estuary]. Product of EcoAdapt's State of Adaptation Program. Retrieved from CAKE:… (Last updated October 2010)

Project Contact(s)

The Partnership for the Delaware Estuary is a nonprofit organization established in 1996 to take a leadership role in protecting and enhancing the Delaware Estuary, where fresh water from the Delaware River mixes with salt water from the Atlantic Ocean. It is one of 28 Congressionally designated National Estuary Programs throughout the coastal United States working to improve the environmental health of the nation's estuaries.

The Environmental Protection Agency has ten Regional offices, each of which is responsible for the execution of the Agency's programs within several states and territories.


Scale of Project
Community / Local
Multilateral / Transboundary
State / Provincial
Sector Addressed
Conservation / Restoration
Development (socioeconomic)
Transportation / Infrastructure
Target Climate Changes and Impacts
Air temperature
Flow patterns
Invasive / non-native species, pests
Range shifts
Salinization / Saltwater intrusion
Sea level rise
Storms or extreme weather events
Water temperature
Climate Type
Type of Adaptation Action/Strategy
Capacity Building
Conduct vulnerability assessments and studies
Governance and Policy
Develop / implement adaptation plans
Taxonomic Focus
Other Invertebrates
Sociopolitical Setting
Effort Stage
In progress

Related Resources