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Browse History: Bay Health Index (2013)
Indicator Icon Bay Health Index

The Bay Health Index is an average of all seven indicators (chlorophyll a, dissolved oxygen, water clarity, total nitrogen, total phosphorus, aquatic grasses, and Benthic IBI) into an overall assessment of Chesapeake Bay health.

Chesapeake Bay - Indicator Details:





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Index Map

Overall Bay health is made up of seven indicators, which include water quality, nutrients, and biotic indicators. In 2013, the overall Bay Health scored a 45%, a C. This is slightly lower than 2012, which was also a C, but 47%. Out of fifteen reporting regions, seven had higher scores in 2013 compared to 2012. The highest-ranked region was the Lower Bay, while the Patapsco and Back Rivers region was the lowest-ranked region.

This map shows the 2013 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; moderate to poor. The exceptions were the Patapsco and Back Rivers region, which had a very poor score. Bay Health Index scores increased in seven regions in 2013 compared to 2012, decreased in eight, and remained steady in one. For more information about the overall health of Chesapeake Bay in 2012, please 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 seven indicators, five water quality indicators and two biotic indicators.

Ranking


Comparison of Bay Health Index scores for 2013 () compared to
()


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

This figure ranks each region from best to worst for the Bay Health Index scores for 2013. These scores are used to provide report card grades (A to F) for each of the regions. The highest ranked region in 2013 was the Lower Bay. 

The lowest ranked region this year was the Patapsco and Back Rivers region, largely due to very poor scores in chlorophyll a, water clarity, total nitrogen and Benthic IBI scores this year. Bay Health Index scores increased in seven regions in 2013 compared to 2012, decreased in eight, and remained steady in one. For more information about the overall health of Chesapeake Bay in 2013 go to the overview page.

*Note that for the Bay Health Index indicator for each reporting region and for overall Bay, all annual scores are calculated using the historical method of six indicators (three water quality, three biotic) averaged into two sub-indices (Water Quality Index and Biotic Index) and then averaged into the Bay Health Index EXCEPT the 2012-2013 scores, which is calculated using the current method of seven indicators averaged into the Bay Health Index. 


Excel Spreadsheet