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Nitrogen in the Chesapeake Bay Watershed—A Century of Change, 1950–2050

Circular 1486
National Water-Quality Program
By: , , , , , , , , , , , , , , , , , , , , , and 
https://doi.org/10.3133/cir1486

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Foreword

Sustaining the quality of the Nation’s water resources and the health of our diverse ecosystems depends on the availability of sound water-resources data and information to develop effective, science-based policies. Effective management of water resources also brings more certainty and efficiency to important economic sectors. Taken together, these actions lead to immediate and long-term economic, social, and environmental benefits that will make a difference to the lives of the almost 400 million people projected to live in the United States by 2050.

The Chesapeake Bay is the largest and most productive estuary in the United States and is a vital environmental and economic resource. Approximately half of the water volume of the Chesapeake Bay originates from streams and rivers that drain the 64,243 mi2 Chesapeake Bay watershed. The Bay and its tributaries have been degraded by excessive nutrients, such as nitrogen, from contributing watersheds. Inputs of nitrogen to the Bay lead to increased algal growth, decreased dissolved oxygen, and declining fisheries. In 2000, the Chesapeake Bay was listed as impaired under the Clean Water Act and Total Maximum Daily Loads (TMDLs) for nutrients and sediment have been established to assist with management actions aimed at nutrient reductions. Effective nutrient management requires an understanding of past, present, and future nutrient sources, fate, and transport in the watershed.

The Chesapeake Bay community has been a pioneer in science, management, and regulation to improve water quality. Factors like climate, hydrology, source inputs, and management controls play a vital role in determining the delivery and magnitude of nitrogen inputs to the Bay. Science in the form of monitoring data, predictive tools, and interpretive reports can help inform decisions to better balance the use and control of nitrogen in coastal areas. The findings in this report can contribute to effective management of the Bay and its watershed by providing a synthesis of the understanding of how human activities and environmental change in the watershed in the past, present, and future will influence the export of nitrogen to the Bay.

We hope this publication will provide you with insights and information to meet your water resource needs and will foster increased civilian awareness and involvement in the protection and restoration of our Nation’s waters. The information in this report is intended primarily for those interested or involved in resource management and protection, conservation, regulation, and policymaking at the regional and national levels.

Suggested Citation

Clune, J.W., and Capel, P.D., eds., 2021, Nitrogen in the Chesapeake Bay watershed—A century of change, 1950–2050 (ver. 1.2, 2024): U.S. Geological Survey Circular 1486, 168 p., https://doi.org/10.3133/cir1486.

ISSN: 2330-5703 (online)

ISSN: 1067-084X (print)

Study Area

Table of Contents

  • Foreword
  • Overview of Major Findings
  • Environmental Setting of the Chesapeake Bay Watershed
  • Nitrogen Setting of the Chesapeake Bay Watershed
  • Historical Setting of the Chesapeake Bay Watershed
  • Chapter 1. Changes in Nitrogen, Water Quality, and Management
  • Chapter 2. Nitrogen in Streams and Groundwater
  • Chapter 3. Changes in Climate
  • Chapter 4. Changes in Hydrology
  • Chapter 5. Changes in Atmospheric Deposition of Nitrogen
  • Chapter 6. Changes in Land Use
  • Chapter 7. Changes in Agricultural Water-Quality Management
  • Chapter 8. Changes in Water-Quality Management in Developed Areas
  • Chapter 9. Modeling the Effect of Nitrogen Loads from Multiple Changes in the Watershed
  • Chapter 10. Watershed Scale Changes in Nitrogen Export: Past and Future
  • Excess Nitrogen Impacts on Coastal Areas Across the Nation and the World
  • Final Thoughts
  • References Cited
  • Glossary
Publication type Report
Publication Subtype USGS Numbered Series
Title Nitrogen in the Chesapeake Bay watershed—A century of change, 1950–2050
Series title Circular
Series number 1486
DOI 10.3133/cir1486
Edition Version 1.0: November 10, 2021; Version 1.1: January 7, 2022; Version 1.2: January 9, 2024
Year Published 2021
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) New York Water Science Center, Pennsylvania Water Science Center, Utah Water Science Center, South Atlantic Water Science Center, VA/WV Water Science Center, Maryland-Delaware-District of Columbia Water Science Center
Description vi, 168 p.
Country United States
Other Geospatial Chesapeake Bay watershed
Online Only (Y/N) N
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details