News Release

Mixed report card for quality of water entering the Chesapeake Bay

Peer-Reviewed Publication

U.S. Geological Survey

Efforts to reduce the amounts of nutrients carried into Chesapeake Bay by its major tributaries are beginning to pay off. Upgrades to wastewater treatment plants, use of no-phosphate detergents, and implementation of a variety of "best management" practices have resulted in decreased concentrations of total nitrogen and phosphorus in some of these rivers, according to a new report by the U.S. Geological Survey (USGS).

Since the mid-1980s, the USGS has monitored amounts of nutrients and suspended sediment in nine major rivers draining to the bay.

The three largest of the monitored rivers show the following trends:

§ A significant decrease in total nitrogen and phosphorus in the Susquehanna and James Rivers over a 14-year and 11-year period, respectively. In the Susquehanna, total nitrogen dropped 12 to 25 percent and total phosphorus dropped 36 to 60 percent. In the James River, total nitrogen dropped 5 to 30 percent while total phosphorus dropped 44 to 69 percent.

§ A significant decrease in suspended sediment in the Potomac River over a 14-year period. During that time, Potomac River sediments decreased 50 to 95 percent.

The health of the bay depends on maintaining these decreasing trends. Too much nitrogen and phosphorus creates blooms of algae, which cut off sunlight and oxygen to the plants and animals that are the foundation of the bay ecosystem.

Lori Sprague, principal investigator and co-author of the report, cautioned that some rivers did not show significant improvements. She noted that human efforts to reduce nutrients are mitigated by natural forces. "A period of heavy rainfall, like we had in early 1998, results in more runoff and higher streamflows, and larger amounts of nutrients and sediment are carried to the bay. On the other hand, it's possible that last year's drought meant that a smaller load entered the bay."

The new report, USGS Water-Resources Investigations Report 99-4238, Monitoring Nutrients in the Major Rivers Draining to Chesapeake Bay, by Donna L. Belval and Lori A. Sprague, contains analyses of 15 years of data from the River Input Monitoring program. The program was established in the mid- 1980s by a coalition of state and Federal agencies working to improve water quality in the bay.

The report is available on-line, along with information about USGS activities in the Chesapeake Bay region, at http://chesapeake.usgs.gov/chesbay/, and can be obtained from the USGS Branch of Information Services, Box 25286, Denver, CO 80225-0286 (1-888-ASK-USGS).

As the nation's largest water, earth and biological science and civilian mapping agency the USGS works in cooperation with more than 2000 organizations across the country to provide reliable, impartial, scientific information to resource managers, planners, and other customers. This information is gathered in every state by USGS scientists to minimize the loss of life and property from natural disasters, contribute to sound economic and physical development of the nation's natural resources, and enhance the quality of life by monitoring water, biological, energy, and mineral resources.

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