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Tributary Summaries

The Chesapeake Bay Program and its partners produce tributary basin summary reports for the Bay’s 12 major tributaries using tidal monitoring data from more than 130 monitoring stations throughout the mainstem and tidal portions of the Bay. These reports use water quality sample data to summarize 1) How tidal water quality (TN, TP, DO, Chlorophyll a, Secchi Depth) has changed over time, 2) How and which factors may influence water quality change over time, and 3) Recent research connecting observed changes in aquatic conditions to its drivers. The available products for each basin are listed below, and the corresponding documents are attached.

  • Choptank (includes the Choptank, Little Choptank, and Honga) Summary, Appendix
  • James (includes the Appomattox, Chickahominy, and Elizabeth Tributaries) Summary and Appendix in one document, Story Map
  • Lower E. Shore (includes the Nanticoke, Manokin, Wicomico, Big Annemessex, and Pocomoke Rivers, and Tangier Sound) Summary, Appendix
  • Maryland Lower Western Shore (includes the Magothy, Severn, South, Rhode, and West rivers) Summary, Appendix
  • Maryland Mainstem (includes the five Chesapeake Bay mainstem segments within the Maryland state boundary. Drainage basins include the Susquehanna River and upper Chesapeake Bay shorelines) Summary, Appendix
  • Maryland Upper Eastern Shore (includes the Northeast, Bohemia, Elk, Back Creek, Sassafras, and Chester Rivers, the Chesapeake & Delaware Canal, and Eastern Bay) Summary, Appendix
  • Maryland Upper Western Shore (includes the Bush, Gunpowder, and Middle rivers) Summary, Appendix
  • Patapsco and Back Summary, Appendix
  • Patuxent (includes the Western Branch tributary) Summary, Appendix
  • Potomac: Summary, Appendix, Story Map
  • Rappahannock (includes the Corrotoman tributary) Summary, Appendix, Story Map
  • Virginia Mainstem: Summary not available, Appendix
  • York (includes the Mattaponi and Pamunkey tributaries) Summary, Appendix

Maps of 2022 Tidal Water Quality Change

The Chesapeake Bay Program (CBP), Maryland Department of Natural Resources (MDDNR), Virginia Department of Environmental Quality (VADEQ), Old Dominion University (ODU), District of Columbia Department of Energy and the Environment (DC DOEE), and Metropolitan Washington Council of Governments (MWCOG) collaborate annually to produce bay-wide summaries of water quality trends in the tidal waters. These annual estimates at more than 150 stations for nutrients, dissolved oxygen, Secchi depth, chlorophyll a and other parameters help gauge the health of the bay and identify changes due to management actions and climate. The 2022 Tidal Trends Summary document attached below summarizes these results. Additional tools are available to explore the tidal trends results including baytrendsmap and the Watershed Data Dashboard, Tidal page.

1. Long-Term Change

Observed change in water quality by station from the beginning of the period to 2022. The beginning of the period varies for stations but is indicated in the bottom right corner of the map.

2. Long-Term Flow-Adjusted Change

Change in water quality by station computed under the condition of average freshwater flow into the Chesapeake Bay over the long-term. This approach answers the question: “What would the change in water quality have been if flow had been average?”

3. Short-Term Change

Observed change in water quality by station over the last 10 years (2013-2022).

4. Short-Term Flow-Adjusted Change

Observed change in water quality computed under the condition of average freshwater flow into the Chesapeake Bay over the last 10 years (2013-2022).

GAM Documentation