MWCOG.org - Water Quality Data

Home > Environment > Water > Water Quality Data

Potomac River Monitoring at Chain Bridge
In 1983, the Metropolitan Washington Council of Governments (COG) established an automated fall line monitor at the Chain Bridge on the Potomac River.
Due to the number of streams discharging into the Bay watershed, and the changing composition of runoff due to storm events, it is challenging to monitor an individual river’s nutrient and sediment contributions to the Bay. However, with careful selection of sampling locations and times it is possible to characterize pollutant inputs from a segment of the Potomac over a range of conditions.

The Chain Bridge station is part of a comprehensive Chesapeake Bay Program monitoring network. The network of rivers being monitored were selected to encompass runoff from as much of the Bay watershed as possible, covering a range of different run off sources to the Bay and its tributaries.

Since the fall line designates the transition from the Potomac River’s free flowing to its tidally influenced section, monitoring at the Chain Bridge location allows estimation of the quality and quantity of upstream nutrient and sediment loads to the Potomac estuary and the Chesapeake Bay.

The Occoquan Watershed
Monitoring Laboratory (OWML)
The Chain Bridge monitoring station is operated by Virginia Tech’s Occoquan Watershed Monitoring Laboratory with funding from the Metropolitan Washington Council of Governments.

The Chain Bridge station is part of a historical data set. Since data collection began in 1983, there have been nearly 27 years of water quality data collected for the fall line of the Potomac River. Because long-term water quality trends can only be established when taken in the context of decades and the broader watershed, it is important for this monitoring to continue.

For additional information about OWML visit their website at: http://www.owml.vt.edu/

In order to access the data online, visit the OWML website for a password.

Recent Publications
Fact Sheet - Potomac River Monitoring at Chain Bridge

Stay tuned for a compreshensive report that describes the monitoring protocol and water quality trends observed at Chain Bridge over the past 20 years.

What is Monitored?
Water quality problems in the Potomac River are caused both by direct inputs of pollutants and indirectly by changes to the land and air that surround and interact with the river. Routine monitoring of river quality includes the following parameters: Total nitrogen (TN), total phosphorus (TP), suspended solids (TSS), total organic carbon, dissolved silica, and other parameters.

The Chain Bridge monitoring station was designed to extract representative samples of the river flow at a variety of stages, ranging from base flow to extreme storm peaks. The river channel around Chain Bridge is relatively narrow and well-mixed because of turbulent flow caused by Little Falls. Most of the flow is constricted into a single channel near the Virginia side of the river thus making retrieval of representative samples practical with the automated sampler. The Chain Bridge Monitoring Station is designed to operate with automatic and manual-command activation. The telephone based computer system installed at Little Falls gauging station would automatically contact Chain Bridge site to activate sampling during storm events.

Contact Information
Steve Bieber (202) 962-3219
Heidi Bonnaffon (202) 962-3219
Christine Howard (202) 962-3366
Mukhtar Ibrahim (202) 962-3394

METROPOLITAN WASHINGTON COUNCIL OF GOVERNMENTS

777 North Capitol Street, NE • Suite 300 • Washington, DC 20002
Phone: 202.962.3200 • Fax: 202.962.3201