Two reports released in April continue to paint a picture of a Bay ecosystem that remains severely degraded despite a quarter century of restoration efforts.
For the second year in a row, the state-federal Bay Program partnership released its Health and Restoration Assessment report in tandem with the release of the Chesapeake Bay 2007 Report Card produced by the University of Maryland Center for Environmental Science.
The Report Card, based on a series of indicators developed by a team of scientists, gave the Bay an overall score of a C- last year, a slight uptick from 2006.
Health and Restoration Assessment presents information about how the Bay and various cleanup activities fared relative to water quality and other goals set by the Bay Program. It provides information about the status of the Bay and cleanup activities, as well as longer trends.
"There are some positive signs of progress and much good work that has been done," said Jeff Lape, director of the EPA's Bay Program Office. "But at the end of the day, what our report cards tell us, is the Bay remains degraded and in a vulnerable state.
"As we move forward, we need to accelerate our actions, reflect on the great science that we have, be willing to change, and be willing to take new actions, and different actions that are more effective."
Scientists reviewing thousands of bits of data collected throughout the Bay and its tidal tributaries last year concluded that, overall, the ecosystem was slightly improved-but not by much.
Overall, their second annual report card gave the Bay a C-, up from a D+ in 2006. But because of the dry conditions that prevailed in 2007, scientists had expected better conditions.
"I'm disappointed that we didn't have a better year," said Bill Dennison, a University of Maryland scientist and the report card project leader. "I thought we had a better year based on the summer drought that we had."
Dry conditions usually mean fewer nutrients and sediments are washed into the Bay, where they degrade water quality.
The influence of the drought, for instance, was likely seen in the Choptank River, which scored an D- -second worst-in 2006, but improved to a D+ last year.
But factors such as extensive algal blooms, and continued poor water clarity kept last year's score from making a more significant rebound, despite some improvements, such as an uptick in underwater grass beds.
The Chesapeake Bay 2007 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.
The Health Index for each localized region is derived by averaging the Biotic Index and Water Quality Index. The Baywide score is determined by averaging the Index for the 14 tributaries and regions it evaluates.
By looking at multiple factors, the index approach avoids distortions that might be caused by looking at a single indicator.
The regions with the best scores were Maryland's Upper Western shore, (65, a B) and the Upper Bay, (59, a C+). Both areas have seen a major resurgence of underwater grasses in recent years as pollution was reduced, and they were characterized as having healthy benthic communities and good dissolved oxygen conditions.
"The Bay is quite resilient, and if we can reduce the nutrients and sediments throughout the Bay watershed, we may be able to see more cases like this," Dennison said.
The worst areas were Maryland's Lower Western Shore and the Patuxent River, both of which scored a 20, for a D-. These areas were plagued by low dissolved oxygen levels, fish kills and algal blooms last summer.
When those, and other regions were averaged together, the Bay as a whole scored a 42, or a C-, up from a 39 last year. The scientists graded last year's score as a D+. (Last year's score was revised upward in this year's report from its original 37 mark to make it consistent with slightly different scoring methodology this year.)
Still, Dennison said, "C- is not an acceptable grade."
In the past year, scientists have assembled information from the last 18 years to piece together a longer-term view of the Bay's health using the index. Their analysis showed no trend, but provided evidence that the Chesapeake would score better if more actions were taken to control nutrients and sediments runoff.
Dennison noted that in 2002, after a long drought kept nutrients from washing into the Chesapeake, the water looked "really good." That year, the Bay scored 54-one of the highest years since 1990.
That was literally washed away as wet conditions returned in 2003, leaving the Bay awash in sediment and nutrients. That year, the Baywide score would have been only 35, one of the worst since 1990.
A related analysis conducted by the scientists showed that tributaries with the greatest amounts of agriculture and development had the poorest scores.
The goal, Dennison said, is to have enough runoff control actions implemented in those watersheds so that the rivers-and the Bay-get a passing grade even in years with normal to high amounts of rain.
"We have to improve our best management practices on the land so that when it does rain again, and rain significantly, it doesn't wash sediment, nutrients and toxicants into the Bay so that we don't have another hit like we had in 2003 and some other years," Dennison said.
The 2007 Chesapeake Bay Health Report Card and supporting information is available at www.eco-check.org/reportcard/chesapeake/.
Chesapeake Bay Report Card Indicators
Bay health is defined as the progress of three water quality indicators and three biotic indicators toward scientifically derived ecological thresholds or goals. These six indicators are combined into one overarching Bay Health Index, which is presented as the Report Card Score.
Water Quality Indicators
Chlorophyll a is used as a measure of phytoplankton (microscopic, floating algae). Excess nutrients stimulate phytoplankton, reducing water clarity, and can lead to reduced dissolved oxygen.
Water clarity is a measure of how much light penetrates through the water column. Suspended sediments and phytoplankton reduce light penetration.
Dissolved oxygen is critical to the survival of aquatic life. Decomposing phytoplankton can lead to reduced dissolved oxygen.
The Benthic Index of Biotic Integrity is a measure of the condition of bottom-dwelling animals (e.g., clams and worms). Low dissolved oxygen levels in bottom waters are detrimental to these animals.
The Phytoplankton Index of Biotic Integrity is a measure of the condition of phytoplankton communities. Light and nutrient availability affects these microscopic, floating algae.
Aquatic grasses, or submerged aquatic vegetation, are one of the most important habitats of the Bay. Light and nutrient levels affect aquatic grass survival.
Sources: Integration & Application Network, University of Maryland Center for Environmental Science and EcoCheck (NOAA_UMCES Partnership)