Combined heavy rains and high nutrient loads in 2003 caused the Bay’s health to drop one point from the previous year in the Chesapeake Bay Foundation’s sixth annual State of the Bay Report.

Overall, the group rated the Bay’s health at 27 on a 100-point scale. That was the same score the Bay got when the CBF started the index six years ago, but a bit better than the 23 that the CBF has said the Chesapeake would have scored during its worst condition in the early 1980s.

The poor showing for 2003 was driven largely by poor water quality conditions which were the result of high loads of nitrogen and phosphorus washed into the Chesapeake by near-record rainfall in the watershed.

The nutrients caused large algae blooms, and also contributed to some of the worst dissolved oxygen conditions seen in the Bay.

In addition to declines in water quality, the foundation also dropped the indexes for sprawl and for blue crabs, whose population is at a near-record low. Those worsening indicators offset higher marks for the shad stock and forest buffers.

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 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 the foundation does say an eventual score of about 70 is possible.

(The CBF originally scored 2002 at 27, but increased that to 28 based on new reports that changed the historic baseline for measuring underwater grass abundance.)

CBF officials have long acknowledged that some indicators are more subjective— such as the measurement of toxics— than others. Nonetheless, it is generally in line with the prevailing view of scientists that the Bay’s condition bottomed out about two decades ago and has made only modest improvement since.

The CBF’s conclusion that the Bay is generally in poor health was mirrored to some degree by a pilot project conducted by the University of Maryland’s Center for Environmental Science, which used a more rigorous scoring approach.

That project created a report card on the health of two major rivers, the Patuxent and Choptank, based on several water quality parameters.

Monitoring data came from 106 sites in the Choptank and 67 sites in the Patuxent, and were graded against “reference” conditions near Cape Charles City, near the mouth of the Bay on Virginia’s Eastern Shore.

Overall, the scientists rated the Patuxent as a D+; the Choptank at a D. The upper parts of both rivers scored an F, while the Middle Patuxent got a C- and the Middle Choptank a D-. The lower Patuxent and lower Choptank both got a D+ while the mouth of the Patuxent got a C and the mouth of the Choptank a D.

The scientists are considering a more ambitious effort in the future for the entire Bay which, like the CBF report, would also include parameters for land use, living resources and habitats.