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The Chesapeake Bay scored a C- in the latest report card assembled by a team of Bay scientists. That's the same grade as last year, although the total score edged up a bit from last year's 39 to 43, on a 100-point scale.
It's the third report in the space of two months to give the Chesapeake a dismal grade, with the state-federal Bay Program giving it a 38 on a 100-point scale in March, and the Chesapeake Bay Foundation ranking it at 28 on a 70-point scale in April.
But the third annual Bay Health Report Card is unique by taking a closer look at 15 regions around the Bay, where it found a more divergent story.
Those areas ranged from B-minus (moderate-good) to F (very poor). The highest ranked region, for the second year in a row, was the Upper Western Shore, which includes the Bush and Gunpowder rivers.
Although the score reflects conditions from last year, data behind the grades for both the Bay and for individual regions stretches back over two decades.
Much of the year-to-year change is driven by the amount of rainfall, which drives nutrients and sediments into the waterways.
But the long-term data show some trends that override that year-to-year variation.
The Upper Bay, for instance, has seen an overall improving trend, driven in large part by the spectacular resurgence of underwater grass beds in that region. Nearby on the Upper Eastern Shore, though, water quality has deteriorated, with underwater grass beds decreasing, coupled with a loss of many bottom-dwelling organisms.
"The best are getting better, and the worst are getting worse," said Bill Dennison, the University of Maryland Center for Environmental Science researcher who leads the report card project.
Most areas, Dennison noted, such as the Choptank, Patuxent and the York, are "going nowhere," as their scores bounce around from year to year based largely on rainfall, with no trend.
Dennison said a key to improving the overall Bay's health is understanding what factors are behind divergent trends in different areas.
The trends, he said, suggest that when areas are improving or worsening, "ecological feedbacks" kick in at a certain point that help to maintain that trajectory. When water quality improves, for instance, it allows for the comeback of underwater grasses, which may further improve conditions.
"These diverging positive and negative trajectories in some of the Bay's key areas show that there are important ecological feedbacks that come into play once restoration efforts reach a certain level," Dennison said.
The report card is based on a Bay Health Index that was developed by a team of scientists from the University of Maryland and several state and federal agencies. It is derived from two indices, each of which integrates three elements:
- The Water Quality Index is determined using information about chlorophyll a (a measure of algae), dissolved oxygen and water clarity.
- The Biotic Index is determined using information about Bay grass abundance, benthic communities and phytoplankton communities.
Each indicator is measured on a 100-point scale, with 100 representing healthy ecosystems based on published scientific literature and technical reports. These are then averaged to get the water quality and biotic indices, both for individual regions and the Bay.
Part of the goal of the project is to spur interest-and action-in local rivers. As a result, the science team has worked with local watershed organizations to help adapt the rating system to their waterways.
The Chesapeake Bay Trust in recent months has supported efforts by the Chester River Association, the Patuxent Riverkeeper and the Severn Riverkeeper to develop report cards, which are supplemented with information gathered by trained volunteers.
"It seems to me that the type of discussions that we should be having are being stimulated by these types of indicators," Dennison said.
Poor reports don't stop at with tidal waters. In addition to their annual report card, scientists for the first time presented a snapshot of ecological conditions in the freshwater streams and rivers that feed the Bay. Data collected at more than 3,200 monitoring sites across the Bay's drainage basin show that degraded streams are found throughout the watershed, especially in significant urban, agricultural or mining areas.
"The health of local streams is almost always the direct result of how we manage the land around them," said Margaret Palmer, UMCES stream ecologist and Chesapeake Biological Laboratory Director. "This new watershedwide look at the health of the Bay's streams tells us we need to be doing more to protect and restore them. Without healthy streams, we will not be able to have a healthy Bay."
The report card's website allows people to zoom in on each of the data points to get more specific information.
Data used in the report card are collected across the entire Maryland and Virginia portions of the Chesapeake Bay by several state and federal agencies as part of the Chesapeake Bay Program. Report card production is supported by Eco-Check, a partnership between the National Oceanic and Atmospheric Administration and the University of Maryland Center for Environmental Science.
The report card and additional information is found at www.eco-check.org/reportcard/chesapeake/2008/overview.
