Salt Line
The Salt Line: What is it and Where is it?

The below graphic shows the current location of the salt line (aka salt front) in relation to several other sites along the river. Estimates of the salt line are based on provisional data and subject to change if better data becomes available.

This graphic shows the location of the salt front.

(RM=  river mile)

One important metric for understanding salinity concentrations in the Delaware Estuary (the tidal Delaware River & Bay) is the seven-day average location of the salt line, the 250 mg/L chloride concentration based on drinking water quality standards. Chloride concentrations indicate the degree to which ocean derived saltwater has moved into the upper portion of the estuary; freshwater flowing downstream from the non-tidal Delaware River helps repel, or flush back, the salt-laced water. While you cannot see the "salt line," its location fluctuates in response to changing freshwater inflows, which either dilute or concentrate chlorides in the river.

DRBC has adopted criteria and monitors chlorides to ensure water quality in the upper estuary remains suitable as a source of drinking water and protective of aquatic life. Additionally, the location of the salt line is tracked by the commission as part of its flow and drought management program, which focuses on controlling the upstream migration of salty water from the Delaware Bay during low-flow conditions. As salt-laced water moves upriver, it increases corrosion control costs for surface water users, particularly industry, and can raise the treatment costs for public water suppliers.

A flow target at Trenton, N.J. has been established by the commission to ensure enough freshwater is flowing downstream to keep the salt line from advancing too far upstream. This flow target is met by either natural flow or by releases from upstream reservoirs during dry conditions. DRBC has the primary responsibility to manage the salt front and meet the Trenton flow target; this is accomplished through directed releases from water that is stored in the U.S. Army Corps of Engineers' Blue Marsh and Beltzville reservoirs, located in Pennsylvania along the Schuylkill River in Berks County and the Lehigh River in Carbon County, respectively. While DRBC does not own these reservoirs, the commission owns storage in them for flow management purposes. Three additional reservoirs, Pepacton, Neversink and Cannonsville, which are owned by New York City and located in the Delaware River's headwaters in the Catskill Mountains in New York State, also have storage that can be used to meet the Trenton flow target.

The next scheduled update is April 13, 2020.