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Browse History: Home (2011) | Water Quality Index (2007) | Aquatic Grasses (2009) | Bay Health Index (2009)
Indicator Icon Bay Health Index

The Bay Health Index combines the Water Quality Index and the Biotic Index into a single overarching score. This score therefore evenly combines all six indicators (chlorophyll a, dissolved oxygen, water clarity, aquatic grasses, Benthic IBI, and Phytoplankton IBI) into an overall assessment of Chesapeake Bay health.

Chesapeake Bay - Indicator Details:





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Index Map

This map shows the 2009 Bay Health Index scores for each of the 15 reporting regions. These scores are used to provide report card grades (A to F) for each of the regions. Most regions of the Bay fell into one of two health grades; poor or moderate. The exceptions were the Upper Western Shore, which had a moderate-good score and the Patapsco and Back Rivers region which had a very poor grade. Bay Health Index scores increased in 11 regions in 2009 compared to 2008, decreased in four, and stayed the same in one. For more information about the overall health of Chesapeake Bay in 2009 go to the overview page.


Creating this map
This map shows the Bay Health Index scores for each the 15 reporting regions. The Bay Health Index for each reporting region is the average of the Water Quality Index and the Biotic Index scores.

Ranking


Comparison of Bay Health Index scores for 2009 () compared to
()


Score Legend
 Score (%)
 0               20               40               60               80              100
  
Upper Western Shore  
Upper Bay  
Lower Bay  
Rappahannock River  
Lower Eastern Shore (Tangier)  
Overall Bay  
Mid Bay  
Potomac River  
James River  
Choptank River  
Upper Eastern Shore  
York River  
Patuxent River  
Lower Western Shore (MD)  
Patapsco and Back Rivers  
Elizabeth River  

This figure ranks each region from best to worst for the Bay Health Index scores for 2009. These scores are used to provide report card grades (A to F) for each of the regions. The highest ranked region in 2009 was the Upper Western Shore (this region was also the highest ranked region in 2008) and second highest ranked was the Upper Bay. One of the reasons these two areas rank so highly is abundant aquatic grasses coverage.

The lowest ranked region this year was the Patapsco and Back Rivers, largely due to a low chlorophyll a and water clarity scores. The Elizabeth River did rank slightly lower than the Patapsco and Back Rivers, but there are only four indicators that are used to calculate the BHI for this region. The Elizabeth River has very poor water quality and phytoplankton community condition. Eight reporting regions had improved grades in 2009 compared to 2008, four were unchanged, and two had slightly worse grades. For more information about the overall health of Chesapeake Bay in 2009 go to the overview page.



Excel Spreadsheet