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Achieving Nutrient and Sediment Reduction Goals in the Chesapeake Bay: An Evaluation of Program Strategies and Implementation (2011)

Chapter: Appendix A: Model Estimated Nitrogen, Phosphorus, and Sediment Loads by Sector for Five Scenarios

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Suggested Citation:"Appendix A: Model Estimated Nitrogen, Phosphorus, and Sediment Loads by Sector for Five Scenarios." National Research Council. 2011. Achieving Nutrient and Sediment Reduction Goals in the Chesapeake Bay: An Evaluation of Program Strategies and Implementation. Washington, DC: The National Academies Press. doi: 10.17226/13131.
×

Appendix A

Model Estimated Nitrogen,
Phosphorus, and Sediment Loads
by Sector for Five Scenarios

TABLE A-1 Total Nitrogen Loads by Source (million pounds per year)

Source 1985 2009 TS TMDL E3
Agriculture 161.8 109.4 71.5 69.4 54.0
Urban runoff 21.0 20.4 15.7 15.6 7.7
Point source 90.9 53.2 44.3 39.1 23.7
Septic 8.2 11.0 7.4 8.4 4.6
Forest 55.9 49.3 50.8 50.9 48.3
NTW atm. deposition 4.1 2.5 2.6 2.6 2.3
All Sources 341.9 245.8 192.3 186.0 140.6
 

TABLE A-2 Total Phosphorus Loads by Source (million pounds per year)

Source 1985     2009 TS      TMDL         E3
Agriculture 9.2 7.3 5.5 5.1 4.4
Urban runoff 2.3 2.4 1.9 1.7 0.6
Point source 10.1 4.2 4.2 3.1 1.0
Septic 0.0 0.0 0.0 0.0 0.0
Forest 2.3 2.4 2.5 2.5 2.5
NTW atm. deposition 0.1 0.2 0.2 0.2 0.2
All Sources 24.0 16.5 14.3 12.6 8.7
 
Suggested Citation:"Appendix A: Model Estimated Nitrogen, Phosphorus, and Sediment Loads by Sector for Five Scenarios." National Research Council. 2011. Achieving Nutrient and Sediment Reduction Goals in the Chesapeake Bay: An Evaluation of Program Strategies and Implementation. Washington, DC: The National Academies Press. doi: 10.17226/13131.
×

TABLE A-3 Total Sediment Loads by Source (million pounds per year)

Source 1985 2009 TS TMDL E3
Agriculture 6,830 5,240 3,794 3,887 3,441
Urban runoff 1,234 1,283 1,067 798 131
Point source 144 71 29 229 32
Septic 0 0 0 0 0
Forest 1,435 1,495 1,577 1,539 1,501
NTW atm. deposition 0 0 0 0 0
All Sources 9,643 8,089 6,467 6,453 5,105
 

NOTES: Loads are as delivered to the Chesapeake Bay under five simulations of the Phase 5.3 watershed model. The scenarios are modeled using the same hydrologic conditions (1985-2005) and changing land use, point source, and BMP conditions. The scenarios include 1985 baseline conditions, 2009 progress, the tributary strategy (TS) goals based on the cap loads set in 2003, total maximum daily load (TMDL), and maximum feasible reduction (E3) scenarios. The E3 scenario is a “what if” scenario of watershed conditions with theoretical maximum levels of managed controls on load sources (“everything, by everyone, everywhere”), with no cost and few physical limitations to implementing BMPs for point and nonpoint sources. Source sectors include agriculture, urban runoff, point sources (including wastewater), septic systems, forested lands, and non-tidal waters atmospheric deposition (NTW Dep). Note that in these simulations, atmospheric deposition is considered separately only when it falls directly on non-tidal waters, and otherwise, the source is attributed to the land-use type on which the deposition falls.

SOURCE: S. Ravi, CBPO, personal communication, 2011.

Suggested Citation:"Appendix A: Model Estimated Nitrogen, Phosphorus, and Sediment Loads by Sector for Five Scenarios." National Research Council. 2011. Achieving Nutrient and Sediment Reduction Goals in the Chesapeake Bay: An Evaluation of Program Strategies and Implementation. Washington, DC: The National Academies Press. doi: 10.17226/13131.
×
Page 185
Suggested Citation:"Appendix A: Model Estimated Nitrogen, Phosphorus, and Sediment Loads by Sector for Five Scenarios." National Research Council. 2011. Achieving Nutrient and Sediment Reduction Goals in the Chesapeake Bay: An Evaluation of Program Strategies and Implementation. Washington, DC: The National Academies Press. doi: 10.17226/13131.
×
Page 186
Next: Appendix B: Best Management Practices and Load Reduction Efficiencies Used in the Watershed Model »
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The Chesapeake Bay is North America's largest and most biologically diverse estuary, as well as an important commercial and recreational resource. However, excessive amounts of nitrogen, phosphorus, and sediment from human activities and land development have disrupted the ecosystem, causing harmful algae blooms, degraded habitats, and diminished populations of many species of fish and shellfish. In 1983, the Chesapeake Bay Program (CBP) was established, based on a cooperative partnership among the U.S. Environmental Protection Agency (EPA), the state of Maryland, and the commonwealths of Pennsylvania and Virginia, and the District of Columbia, to address the extent, complexity, and sources of pollutants entering the Bay. In 2008, the CBP launched a series of initiatives to increase the transparency of the program and heighten its accountability and in 2009 an executive order injected new energy into the restoration. In addition, as part of the effect to improve the pace of progress and increase accountability in the Bay restoration, a two-year milestone strategy was introduced aimed at reducing overall pollution in the Bay by focusing on incremental, short-term commitments from each of the Bay jurisdictions.

The National Research Council (NRC) established the Committee on the Evaluation of Chesapeake Bay Program Implementation for Nutrient Reduction in Improve Water Quality in 2009 in response to a request from the EPA. The committee was charged to assess the framework used by the states and the CBP for tracking nutrient and sediment control practices that are implemented in the Chesapeake Bay watershed and to evaluate the two-year milestone strategy. The committee was also to assess existing adaptive management strategies and to recommend improvements that could help CBP to meet its nutrient and sediment reduction goals.

The committee did not attempt to identify every possible strategy that could be implemented but instead focused on approaches that are not being implemented to their full potential or that may have substantial, unrealized potential in the Bay watershed. Because many of these strategies have policy or societal implications that could not be fully evaluated by the committee, the strategies are not prioritized but are offered to encourage further consideration and exploration among the CBP partners and stakeholders.

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