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Browse History: FAQ (2008)

Chesapeake Bay - Frequently Asked Questions:



General

What is the Chesapeake Bay annual ecosystem health report card?
The report card is a scientifically robust and geographically detailed annual assessment of Chesapeake Bay ecosystem health. The report card combines multiple indicators (regarding water quality and habitat) of ecosystem health into a single score for 15 regions the Bay.

When is the report card released?
The report card is expected to be released annually in early to mid April.

How does the report card score ecosystem health?
Currently, this report card rates Chesapeake Bay health as defined by progress of six indicators toward established scientifically derived ecological thresholds or goals. A low report card score therefore means that the area of interest rarely meets the ecological threshold levels. A high score means that the area often meets the threshold levels.

How many indicators does the report card include?
There are three water quality indicators (chlorophyll a, dissolved oxygen, and water clarity) and three biotic indicators (aquatic grasses, Benthic Index of Biotic Integrity, and Phytoplankton Index of Biotic Integrity). Other indicators, especially those related to fish and shellfish, will be added to the report card in the future as suitable data becomes available.

How were the report card indicators chosen?
Indicators for the Chesapeake Bay report card were chosen so that they would relate to the management objectives established in the Chesapeake 2000 Agreement, represent key ecological processes, and fulfill practical requirements such as data availability and geographic coverage.

Does the report card address human health issues?
No - Indicators used in the report card have been chosen to measure the health of the Bay's ecosystem and not how healthy the Bay is for human use, such as swimming and fish consumption.

What do the grades mean?
A: All water quality and biological health indicators meet desired levels. Quality of water in these locations tends to be very good, most often leading to very good habitat conditions for fish and shellfish.

B: Most water quality and biological health indicators meet desired levels. Quality of water in these locations tends to be good, often leading to good habitat conditions for fish and shellfish.

C: There is a mix of good and poor levels of water quality and biological health indicators. Quality of water in these locations tends to be fair, leading to fair habitat conditions for fish and shellfish.

D: Some or few water quality and biological health indicators meet desired levels. Quality of water in these locations tends to be poor, often leading to poor habitat conditions for fish and shellfish.

F: Very few or no water quality and biological health indicators meet desired levels. Quality of water in these locations tends to be very poor, most often leading to very poor habitat conditions for fish and shellfish.

What are the factors that affect the grades on a long-term basis?
There are several factors that affect the grades on a multi-year scale. The amount of rainfall in the area can influence how much nutrients and sediment enter the Bay. For example, in 2002 the Bay scored a 55% because there were several years of low rainfall. But after the wet conditions of 2003, the health of the Bay deteriorated to a 36%, and has not recovered quickly. Another factor affecting the bay's health on a multi-year basis is the amount of restoration and best management practices that are occurring throughout the bay watershed. For example, stormwater retention ponds and wastewater treatment plant upgrades help to keep the bay clean, but it can take multiple years to implement and measure the benefits of these practices.


2008

What were the conditions affecting Bay health in 2008?
The amount of nutrients and sediment deposited into Chesapeake Bay is strongly related to river flow rates and hence, weather conditions. Stream flow, measured by USGS, was average in 2008, with some months (June through September) below average. Based on 2008 stream flow, we can assume that the amount of nutrients and sediment coming into the bay were also average. 2008 nutrient and sediment data are not available at the time of the report card release.

What was the overall health of Chesapeake Bay in 2008?
The overall health score for Chesapeake Bay in 2008 was 43 out of a possible 100 points. This score shows that overall health was moderately poor. However, the health of the bay varied from region to region; some regions had relatively good health, such as the Upper Western Shore and the Upper Bay, while other regions had poor health, such as the Lower Western Shore (MD) and from the Patuxent River north to the Back River.

Why was the Upper Western Shore so healthy in 2008?
The Upper Western Shore region had the highest health index score for the second year in a row, with a score of 64%. This high score is largely due to a resurgence in aquatic grasses (79% towards the goal) and benthic (bottom-dwellers) condition. Dissolved oxygen continues to pass the threshold 100% of the time and over the entire region.

Why was the Upper Bay so healthy in 2008?
The Upper Bay faces the challenge of being geographically close to and fed by the mouth of the Susquehanna River and the loads of nutrients it transports. Despite being close to the Susquehanna, the Upper Bay region had the second highest report card scores in 2008. Relatively good conditions in this area may be due to high flushing rates, rapidly pushing sediment and nutrients into more southern regions of the Bay. Ecosystem indicators leading to the high score include the chlorophyll a score, a healthy phytoplankton community, and continuing recovery of aquatic grasses, especially on the Susquehanna flats.

Reporting regions from the Patuxent River north to the Back River scored the worst in 2008. Why?
Low scores in this region of the bay are likely due to the large human population living in watersheds that drain into relatively small rivers. While each region scored poorly in 2008, the indicator scores underpinning the Bay Health Index did differ slightly between regions. For example, the Phytoplankton Index of Biotic Integrity scores ranged from 10% (Patapsco and Back Rivers) to 26% (Lower Western Shore, MD), and the aquatic grasses scores ranged from 5% (Patapsco and Back Rivers) to 22% (Lower Western Shore, MD).

How healthy were aquatic grasses in 2008?
Overall, there was a slight increase in aquatic grasses in 2008. Regions recording the largest percentage increase were the Upper Bay, Rappahannock River, and Upper Western Shore. In 2007, the Patuxent River, Upper Eastern Shore, and Patapsco and Back Rivers regions experienced a decrease, but each had a slight increase this year.