Driven by accelerated sprawl and blue crab declines, the Bay dropped one point this year in the Chesapeake Bay Foundation’s annual assessment of the estuary’s health.

Declines in those two categories outweighed restoration progress with shad and forested stream buffer plantings to drop the Bay’s 2001 score to 27 on the CBF’s 100-point scale.

The score of 27 is worse than the score of 28 in 1999 and 2000, and the same as what the CBF rated the Chesapeake in 1998, the first year of its annual “State of the Bay” report.

“This is less about what has changed than what hasn’t changed,” said Mike Hirshfield, CBF vice president for resource protection. “The overall state of the Bay isn’t really changing significantly. It is sort of stuck in this rut down in the high 20s.”

The lack of major change is largely due to the failure to significantly improve water quality. Many of the CBF’s 13 indicators — nitrogen, phosphorus, water clarity, dissolved oxygen — are directly tied to water quality.

Others — such as underwater grasses, which require good water clarity to survive, and blue crabs which thrive in grass beds — are indirectly tied to water quality. “If we want to see more progress,” Hirshfield said, “we are going to have to do more.”

The CBF assessment of water quality roughly parallels the Bay Program’s monitoring, which has shown no Baywide improvement in water quality or underwater grass beds in the past decade.

To come up with its score, the CBF compares the current status of 13 indicators with what their condition is thought to have been prior to European settlement. It then averages those scores together to come up with the overall index. A perfect 100 score would represent a “pristine” Bay, which the CBF acknowledges is unattainable. But it does say an eventual score of about 70 is possible.

In some cases, the scores are straightforward: Underwater grasses rate a 12 because they are thought to cover about 12 percent of their historic area, and nitrogen rates 15 because it’s thought that the Bay gets 6 to 7 times more of the nutrient than it would receive under pristine conditions. Other categories, such as toxics, tend to be more subjective.

This year’s reduced scores for crabs and sprawl came in the report’s more subjective categories, Hirshfield acknowledged. Nonetheless, he said, the declines reflect new data showing that the condition for both categories was worse than earlier assumed.

The CBF earlier estimated that about 90,000 acres of land was developed annually in the watershed, but a U.S. Department of Agriculture report released earlier this year put the rate at 128,000 acres annually. The CBF said that the USDA’s number was probably too high, but that the actual rate of development was probably higher than the organization originally estimated.

The drop in the crab index was based on continued harvest declines coupled with recent scientific reviews indicating that the blue crab population is in worse shape than previously thought.

Not all of the news was bad. This year’s strong shad run brought a 1-point gain in that category, although shad still scored only a 6 because the Baywide stock remains at a fraction of its historic level. Also, forest buffers gained a point, as the CBF estimated that 54 percent of all streams in the watershed are now buffered by trees, which absorb nutrients and improve stream habitat. “There is a lot more buffer restoration than anyone ever expected, and we see that accelerating, not slowing,” Hirshfield said. “And it was another record year for shad. That is something to celebrate.”

The CBF said it would like to see the score increase to 40 by the end of the decade. That, Hirshfield said, is roughly where the Bay would be if the Chesapeake 2000 Agreement is implemented.

The agreement calls for cleaning up the Bay by 2010, something that would likely require nutrient reductions of about 50 percent over the next decade. Those reductions, couple with related improvements in water quality and underwater grasses, would probably be enough to boost the score to about 40, he said.