Hudson River Salt-Front Monitoring Project, New York

Hudson River from Hyde Park to Yonkers, N.Y.

Continuous since October 1991

Problem - The location of the salt front (freshwater-saltwater interface) in the lower Hudson River basin can affect wildlife habitats and freshwater withdrawals for municipal use. Knowing the location of the salt front can help managers make informed decisions to protect the environment, maintain drinking water standards, and issue health advisories pertaining to drinking water, if needed.

Objectives - Estimate the location of the salt front (defined as 100mg/L chloride) in the lower Hudson River. Specifically, collect water-surface elevation, specific conductance, and water-temperature data at three gages on the lower Hudson River and utilize regression equations to predict where the salt front is located at high slack tide. Prior to 2010 the program was funded by the New York State Department of Environmental Protection and included development and maintenance of the regression equations that relate the mean-daily specific-conductance data from the Poughkeepsie, West Point, and Hastings-on-Hudson gages to the location of the salt front.

On November 12, 2010, data collection at Hasting-on-Hudson was discontinued and a new gage at Piermont, NY, was installed as a replacement. A new regression relating mean-daily specific conductance at Piermont to the location of the salt front was developed and put into effect on November 12, 2010.

Water-surface elevation, specific conductance, and water temperature data are available for five gage locations on the Hudson River -- below Poughkeepsie (May 1992 to current year), at South Dock at West Point (October 1991 to current year), at Tomkins Cove (December 1996 to June 2001), near Congers (April 1997 to June 2001), and south of Hastings-on-Hudson (May 1992 to November 2010), and Piermont (November 2010 to current year). These data are available in annual data reports and on the worldwide web at http://ny.usgs.gov .

Real-time data for the Hudson River Salt-Front Project (including the daily estimated location of the salt front), and the three monitoring gages used to estimate the salt-front location can be found at the following links:

• Hudson River Salt-Front Monitoring Project
• Hudson River below Poughkeepsie, NY
• Hudson River at South Dock at West Point, NY
• Hudson River at Piermont, NY