Good news about the Chesapeake Bay used to be as scant as oyster harvests. But in the past few years, headlines have brightened. The six bay states andWashington, D.C., all agreed to implement a blueprint for cleaning up the bay and its tributaries. The blue crab population surged. This spring, the Maryland legislature acted boldly to accelerate pollution reduction from sewage and stormwater systems, and from sprawl development.