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Setting and Allocating the Chesapeake Bay Basin Nutrient and Sediment Loads: The Collaborative Proce

The Chesapeake 2000 agreement has been guiding Maryland, Pennsylvania, Virginia and the District of Columbia, the Chesapeake Bay Commission and the U.S. Environmental Protection Agency (EPA) in their combined efforts to restore and protect the Chesapeake Bay. It defined the goal to achieve and maintain the water quality necessary to support the aquatic living resources of the Bay and its tributaries and to protect human health. Subsequently, Delaware, New York and West Virginia signed a Memorandum of Understanding committing to implement the Water Quality Protection and Restoration section of the agreement.

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Technical Tools Used in the Development of Virginia's Tributary Strategies: A Synthesis of Airshed,

The overall modeling framework used to assess Virginia's tributary strategies in 1999 is documented. This synthesis report provides an overview of the Chesapeake Bay Program airshed, watershed, and estuary models and other diagnostic tools which were applied to determine tributary allocations for each of the four lower Virginia basins; the Rappahannock, York, Hames, and Easter Shore Virginia. The publication describes the model scenarios developed to test various management options aimed at improving water and bay grasses quality through different levels of nutrient and sediment reductions. Tracer analyses are presented to better understand the hydrologic interactions among tributaries and the mainstem Bay. Watershed and estuarine physical descriptions, flows and nutrient and sediment loadings of the lower Chesapeake Bay system are detailed. As responses to these loadings, modeled measures of water and habitat quality, needed to sustain key living resources, are interpreted and address.

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Review of Phase 5 Watershed Model Hydrologic Calibration

The hydrologic calibration of the phase 5 watershed model was evaluated through 9 published acceptable criteria used in HSPF Expert system. The specific flow characteristics evaluated are: Error in total volume; Error in low flow or base flow recession; Error in 50% lowest flow; Error in 10% highest flow; Error in storm volumes; Summer volume error; Winter volume error; Summer storm volume error; and Storm peaks simulated verses observed for selected storms in inches. One Phase 5 base flow statistic was also used.

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Tidal Sediment Yield Estimate Methodology in Virginia for the Chesapeake Bay Program Water Quality M

Water quality in Chesapeake Bay has degraded over the past 50 years with respect to oxygen depletion and reduced light attenuation. While the causes are numerous, sediment resuspension from wave and tidal action cloud the water column and reduce light attenuation thereby negatively affecting submerged aquatic vegetation (SAV) beds. Sediments on the Bay bottom come from upland runoff and shoreline erosion, each of which has significant contributions to the loading of sediments into estuary. The purpose of this report is to assess the present methods used to calculate sediment loading from tidal shoreline erosion that is input to the Chesapeake Bay Water Quality Model (WQM).

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