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Chesapeake Bay Watershed Model Application & Calculation of Nutrient & Sediment Loadings - Appendix F: Phase IV Chesapeake Bay Watershed Model Point Source Loads

Published: August 15, 1998

Appendix F documents in detail the Phase IV Chesapeake Bay Watershed Model point source nutrient data assimilation process for the facilities located in signatory and non-signatory jurisdictions of the Chesapeake Bay Watershed. This document includes a description of the data sources, the methods of assimilation, types of analysis performed to determine nutrient reduction estimates, and trends in nutrient loadings discharged to the Chesapeake Bay Watershed. The Phase IV Watershed Model Point Source Database includes information for approximately 612 (the exact number varying depending on the year) active industrial, municipal, and federal facilities discharging directly to surface waters within the Chesapeake Bay watershed from all signatory and non-jurisdictions including: New York, Pennsylvania, Maryland, Delaware, District of Columbia, Virginia and West Virginia. Facility information, and flow and loading data are included for each of the 612 facilities for the years 1985 through 1996, 2000, Tributary Strategy Implementation (which is expected to occur after the year 2000) and additional nutrient reduction scenarios. The following flow and loading parameters are included: flow, total nitrogen, nitrate, organic nitrogen, total phosphorous, phosphate, organic phosphorous, biochemical oxygen demand, and dissolved oxygen.The nutrient point source loading data can be presented in both loads discharged at end of pipe and loads delivered to the Chesapeake Bay. To determine delivered loads, delivery factors were applied to the discharged loads to estimate attenuation as loads travel down the tributaries to the mainstem of the Chesapeake Bay. The total nitrogen load delivered to the Chesapeake Bay has decreased by 14 percent from 1985 to 1996, and is expected to decrease 27 percent from 1985 to 2000, and 33 percent from 1985 and Tributary Strategy Implementation (after 2000). These reductions are primarily due to facilities implementing biological nitrogen removal. The total phosphorous load delivered to the Chesapeake Bay has decreased 50 percent from 1985 to 1996, and is expected to decrease 55 percent from 1985 to 2000.

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Originator: Chesapeake Bay Program
EPA Number: 903-R-207-98
CBP Number: CBP/TRS 207/98

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