During the 2014 water year (October 2013 to September 2014), approximately 285 million pounds of nitrogen reached the Chesapeake Bay. This is below the long-term average of 339 million pounds per year. River flow averaged 53 billion gallons per day during this time, which is close to the long-term average of 51 billion gallons per day.
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Each day, billions of gallons of fresh water flow from rivers and streams into the Chesapeake Bay. The amount of water flowing from these tributaries into the Bay has a direct impact on pollution: as snowmelt or rainfall increase river flow, more nutrients and sediment are pushed into the estuary. In other words, precipitation and river flow are factors affecting pollution loads and water quality.
Nutrient pollution is one of the leading causes of the Bay’s poor health. When nitrogen and phosphorus enter rivers, streams and the Bay, they fuel the growth of algae blooms that lead to low-oxygen “dead zones” that are harmful to fish, shellfish and other aquatic life.
In 2014, the Chesapeake Bay Program adopted a goal to reduce pollution loads and achieve the water quality necessary to protect human health and support the region’s underwater resources.
The amount of nitrogen delivered to the Chesapeake Bay can change dramatically from year to year and is influenced by changes in land use, land management and river flow. This complicates our efforts to determine trends in nitrogen loads over time.
During the 2014 water year (October 2013 to September 2014), approximately 285 million pounds of nitrogen reached the Bay. This is below the long-term average of 339 million pounds per year and 23 million pounds less than the 2013 load. River flow averaged 53 billion gallons per day during this time, which is close to the long-term average of 51 billion gallons per day.
Scientists use the following information to estimate nitrogen loads to the Chesapeake Bay:
This indicator helps us understand and explain trends in nitrogen loads and water quality. Another indicator—Reducing Nitrogen Pollution—reports computer-simulated estimates of the amount of nitrogen delivered to the Bay following the implementation of efforts to reduce pollution. These estimates are generated with the Chesapeake Bay Program’s Watershed Model (Phase 5.3.2), and help us understand the effects of our management actions on pollution loads and develop “what-if” scenarios that project the future impacts of our actions on water quality. Because of the differences in the data behind these indicators, it is possible for them to report different pollution load amounts in a particular year.