The Bay’s health was scored at 29 on a 100-point scale in the Chesapeake Bay Foundation’s most recent “State of the Bay” report—the highest mark ever given by the environmental group. Nonetheless, the Bay still got a “D” grade.

“Despite the improvements reflected in this year’s score, the Bay remains in critical condition,” said CBF President Will Baker. “Fish kills, beach closures and dead zones are clear reminders that much more needs to be done.”

Much of the two-point improvement from last year’s mark was attributed to near-record-low spring rainfall, which flushed fewer nutrients and sediment off the land and into the Bay. But the report also suggested that some actions on the land to reduce nutrients are beginning to have an impact.

To come up with its index, which the group began in 1998, the CBF compares the current status of 13 indicators with what their condition is thought to have been before 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 says is unattainable. But the foundation does say an eventual score of about 70 is possible. The report’s previous high mark was 28 in 2000.

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 Chesapeake’s condition bottomed out about two decades ago and has made only a modest improvement since then.

Here are the scores for 2006, and the CBF’s basis for changes from 2005:

Nitrogen: 17, Up 4 & Phosphorus: 29, Up 9

The figures reflect the impact of a dry spring, which reduced the amount of nutrients washing off the land, but may also indicate that restoration efforts aimed at reducing wastewater treatment plant discharges and controlling agricultural runoff are having an effect.

Dissolved Oxygen: 16, Up 4

The summertime area of “anoxic” water—areas with no oxygen—was smaller than what it was in recent years, a reflection of reduced nutrient inputs. But summer oxygen concentrations are still far from that of a “healthy” ecosystem.

Water Clarity: 15, No Change

Water clarity was better than average during much of the spring, but that changed when heavy rain hit the watershed in late spring and early summer, washing huge amounts of sediment into the Bay.

Toxics: 27, No Change

Reported toxics releases have shown little change, and concern about the effect of chemical contaminants on fish have been highlighted by the finding of large numbers of “intersex” fish—those with both male and female characteristics—in parts of the Potomac River basin.

Riparian Forest Buffers: 56, Up 1

Streamside forest plantings have accelerated in recent years, although the majority of existing forest buffers lack permanent protection and state field staffs to promote buffers have been reduced.

Wetlands: 42, No Change

Watershed states restored 10,000 acres of wetlands since 1998, but recent Supreme Court rulings and proposed federal regulatory changes could weaken protections. Projects such as the proposed Intercounty Connector highway in Maryland and the King William Reservoir in Virginia also threaten large wetland tracts.

Underwater Grasses: 18, Down 2

The decrease reflects lingering effects from the widespread defoliation of eelgrass in 2005. Grass beds in the upper Bay remained abundant and diverse despite heavy rains in late spring.

Resource Lands: 29, No Change

Development continues to consume 90,000 acres of watershed farms and forests a year. Preservation programs offset some losses, but the CBF said policy changes are needed to manage growth.

Rockfish: 71, No Change

Striped bass populations remain near historic highs, but widespread disease among the population suggests the current state of the Bay—with fewer menhaden and poor water quality—may not be able to support such a large population.

Blue Crabs: 38, No Change

The population remains stable at a low level, but harvest has remained below target levels, which may help the population rebound. The widespread loss of eelgrass in 2005 may have reduced the survival of juvenile crabs.

Oysters: 4, Up 1

A record-setting 300 million hatchery-reared oysters were placed in the Bay and its tributaries this year, and harvests increased over 2005 levels in both Maryland and Virginia.

Shad: 10, Down 1

Shad runs were weak this spring and declines in shad numbers continue in both the York and Susquehanna rivers, which historically have been key spawning areas.