Factors Impacting Bay and Watershed Health

In the 1600s, forests  covered 95 percent of the watershed. Now only 55 percent of the watershed is  forested.

Everything that happens on the land affects the health of the Chesapeake Bay and its local waterways. Human activities and natural factors have a significant influence on the health of the Bay and its watershed.

The Bay Program uses the most current monitoring data to track the major factors that influence the health of the Bay and its watershed.

Pollutants

The Bay and its rivers are unhealthy primarily because of excess nitrogen, phosphorus and sediment pollution.

• Nitrogen: Preliminary estimates show that approximately 455 million pounds of nitrogen reached the Bay during the 2011 water year.
• Phosphorus: Preliminary estimates show that approximately 48 million pounds of phosphorus reached the Bay during the 2011 water year.
• Sediment: Preliminary estimates show that approximately 25.8 million tons of sediment reached the Bay during the 2011 water year.

Land Use

The Bay’s decline is directly linked to population growth and corresponding development. Human activities offset efforts to clean up the Bay and its rivers. The Bay also needs enough healthy forests throughout the watershed to protect the health of local waterways.

• Population Growth: As of 2011, 17.5 million people were estimated to live in the Bay watershed.
• Forest Cover: 58 percent of the Bay watershed is forested, and development is reducing forests at the rate of 100 acres per day.

Natural Factors

Natural factors such as precipitation have an enormous effect on the Bay’s health. Annual rain and snowfall determine how much water flows in rivers. The amount of pollution flowing into the Bay each year generally corresponds with the volume of water that flows from its rivers and the concentration of pollutants in that water.

• River Flow: Annual average river flow to the Bay during the 2012 water year (October 2011-September 2012) was 52 billion gallons per day. This is 21 billion gallons per day less than 2011 and close to the 51 billion gallon per day average flow from 1937-2012.