Delaware River Battling Saltwater Intrusion Due To Drought

The Delaware River overlooking Trenton, N.J. flows downstream as seen from from Morrisville, Pa., on Monday, Nov. 25, 2024. (AP Photo/Mike Catalini)

Officials are closely monitoring the encroachment of saltwater into the Delaware River, a vital source of drinking water for millions, including Philadelphia. The salt front, where ocean saltwater meets freshwater, has moved about 20 miles north due to drought conditions in the Northeast, raising concerns about potential impacts on drinking water intakes.

What is the salt front?

The salt front, or salt line, marks the boundary where saltwater and freshwater converge in the river. Normally located around Wilmington, Delaware, the recent drought has pushed it northward, nearing critical drinking water intakes.

Why does it matter?

The proximity of the salt front to drinking water intakes poses a risk to water quality. Desalination of saltwater is costly and energy-intensive, making it an impractical solution.

What are officials doing?

Drought pushed salt front 20 miles north, threatening drinking water intakes.

Salt front marks saltwater-freshwater boundary in the Delaware River.

Officials releasing water from reservoirs to push salt front downstream.

Similar saltwater intrusion occurred in 2016 during a previous drought.

Officials are releasing water from reservoirs to push the salt front downstream. Monitoring at Trenton helps gauge the impact, with adjustments made to maintain a sufficient flow rate to protect drinking water sources.

When was the last similar event?

A similar saltwater intrusion occurred in 2016 during a previous drought, highlighting the vulnerability of the region's water supply.

Is this phenomenon common?

Saltwater intrusion is a concern in other regions, such as the Mississippi River, due to rising sea levels and altered riverbeds.

What caused the saltwater movement?

The drought in the Northeast reduced river flow, allowing denser saltwater to move upstream, necessitating intervention to safeguard drinking water.

What are the future plans?

The Delaware River Basin Commission is studying climate change impacts on water resources and exploring options like additional storage and conservation measures to address long-term water security.

While recent rainfall has provided some relief, sustained precipitation is needed to restore the salt front to its normal position. Water managers emphasize the importance of proactive planning and resource management to ensure a reliable water supply for the region.