The Delaware River Basin Commission has released a new report evaluating how sea level rise will affect the amount of salt water in the Delaware Bay and portions of the tidally influenced river.
The DRBC details how far upstream salt water or salinity could reach under multiple sea level rise scenarios and flow conditions in the Delaware River, the largest undammed river in the eastern United States. Generally, sea level rise is expected to push the salt front — the location where the river is no longer considered fresh water — farther upstream than typically seen today.
Key water intakes in the tidal portion of the Delaware River provide drinking water to over 1.3 million people in Philadelphia, Southeastern Pennsylvania and South Jersey, and support economic activity, including manufacturing and power generation.
When sea level rise exceeds half a meter, the DRBC’s current management strategies — primarily releases of freshwater from reservoirs in multiple states to dilute the salt water — may no longer be effective.
“The commission must be prepared to consider new approaches to ensure an adequate and equitable supply of suitable quality water for Delaware River Basin water users and the environment,” said DRBC executive director Kristen Bowman Kavanagh. “This report tells us in the clearest terms additional fresh water supplies may be needed in the future.”
Computer modeling was used to compare salinity in the river to baseline conditions for five sea level rise scenarios ranging from 0.3 meters to 1.6 meters, under varying drought conditions, and considering other factors, such as river flows and changes to channel depth that may influence the transport of salt water into the tidal portions of the river.
Potential policy and management changes are outlined in the report and include releasing large pulses of water to help temporarily push the salt front downstream and adopting a more dynamic approach to water releases from two reservoirs in Pennsylvania.
“We commend the DRBC’s foresight to plan for a changed water future,” said Jill Whitcomb, Pennsylvania DEP deputy secretary for water and alternate DRBC commissioner. “By working collaboratively through the DRBC, we can continue to ensure regional water security in a changing climate.”
“The Delaware River is a shared water resource, which makes regional management critical to long-term water supply and resilience planning,” said Mark McDonough, president of New Jersey American Water. “We value the DRBC’s proactive efforts to study and address these issues, which help ensure the sustainability of this vital resource for generations to come.”
The DRBC’s Advisory Committee on Climate Change reviewed the draft report prior to its publication. The commission launched the ACCC in 2019 to provide the commission and the basin community with expertise, information and advice.
“The DRBC plays a unique role in managing our interstate Delaware River, and the ACCC adds value by sharing perspectives and information on climate-related science,” said Tom Gilbert, ACCC member and president of the Pennsylvania Environmental Council. “Between climate change and growing water resource-consumption concerns, it’s more important than ever that we plan and prepare for a future that will put increasing pressure on the vital water resources of the Delaware River Watershed.”
The recently published report (PDF), along with a companion model calibration report, is available on the DRBC’s website, drbc.gov, and the DRBC will host a Jan. 27 webinar on the report.
The DRBC says it has been evaluating the impacts of climate change and sea level rise to water resources throughout the basin. Recently, the DRBC kicked off its first-ever basinwide Water Resources Resilience Plan.
Phase One of the plan, expected to be finalized in 2026, has a goal to ensure the scope of the WRRP considers public and partner concerns about climate change and water resources.
DRBC’s ongoing resilience and adaptation work also includes re-evaluating the drought management plan and investigating reservoir storage opportunities to ensure a sustainable supply of water, especially if more freshwater is needed to dilute salt water; the creation of a unique basinwide tool to evaluate future precipitation; and connecting communities with funding opportunities for flood hazard mitigation projects.
The DRBC is a federal/interstate government agency created in 1961 by concurrent compact legislation, marking the first time that the federal government and a group of states joined together as equal partners in a river basin planning, development and regulatory agency.
The five commission members are the governors of the basin states (Delaware, New Jersey, New York and Pennsylvania) and the commander of the U.S. Army Corps of Engineers’ North Atlantic Division, who represents the federal government.
The Delaware River (pictured here from the New Hope-Lambertville Bridge) is at risk from a number of climate-related threats.,
