Delaware • New Jersey • Pennsylvania
New York • United States of America
The salinity, or salt content of water in the Delaware Estuary, depends on the balance between flow and tides. Ocean tides bring salty water into the Estuary while freshwater flowing downstream pushes salty water back toward the ocean. In the upper estuary, lower salinity water van still be used for drinking water (with treatment), industrial and manufacturing processes, and thermoelectric power generation. Higher salinity waters can affect the taste and odor of even treated water, affect manufacturing processes, and corrode equipment due to its corrosive qualities. Salt cannot be removed from water without expensive and energy intensive treatment. The salt front is used to estimate how far saltwater has moved into the estuary, known as salinity intrusion, and is defined as the location where the chloride concentration is 250 mg/l based on a seven-day moving average.
Use the navigation buttons on the left to explore the data. Descriptions of the navigation buttons are below the plot.
How the Salt Front is calculated: Link to report
Links to Data (updated monthly): Text File | Excel File | River Mile System | Boat Run Data
Learn More about the Salt Front
History of the Salt Front Presentation
The range of the salt front by month are represented by the box-whisker plot above. The boxes represent the normal range (between the 25th and 75th percentile) for each month. The red horizontal line in the box represents the median. The red dot in the box represents the mean. The grey vertical lines or whiskers above and below each box represent the 10th and 90th percentile range of the salt front. The black points above and below the whiskers represent values of the salt front below and above the 10th and 90th percentiles, respectively. The period of record summarized with the box plot is October 1963-December 2022.
This animated graphic shows the movement of the salt front in the Delaware River Estuary during the months of July 1964 through January 1965. The Delaware River Basin was extremely dry during these months, allowing the salt front to travel upstream to river mile 102, just 8 miles south of Philadelphia's drinking water intakes on the Delaware River. River mile 102 was the highest recorded location of the salt front.
This animated graphic shows the movement of the salt front in the Delaware River Estuary during the months of July through November 1965. The Delaware River Basin was dry during these months, allowing the salt front to travel upstream to approx. river mile 95, just a few miles north of the Schuylkill River's confluence with the Delaware River.
This animated graphic shows the movement of the salt front in the Delaware River Estuary during the months of July through November 2002. The Delaware River Basin was dry during these months, allowing the salt front to advance upstream to river mile 89 near the Philadelphia International Airport.
This animated graphic shows the movement of the salt front in the Delaware River Estuary during the months of July through November 2017. The Delaware River Basin experienced normal hydrologic conditions during these months; the salt front never reaches the Commodore Barry Bridge, staying mostly within its median range.
