The 40 percent nitrogen reduction goal the Bay states are struggling to achieve has shrunk since it was set by the Executive Council in 1987.

After setting the reduction goal (measured from a 1985 baseline year), the states and the EPA decided that the agreement meant a reduction only in "controllable" sources of nutrients to the Bay. Natural "background" sources of nutrients were considered "uncontrollable."

So were nutrients originating from portions of New York, West Virginia and Delaware that are within the watershed. Also excluded was nitrogen from air pollution, septic systems and other difficult-to-quantify sources.

For nitrogen in particular, what was considered "controllable," was only a fraction of the total amount entering the Bay. In 1992, the Bay Program agreed that a 40 percent reduction in the "controllable" nitrogen load was only 74 million pounds from the 365 million pounds estimated to have en-tered the Chesapeake in 1985.

That would be a reduction of about 20 percent of the total nitrogen entering the Bay.

The past year's re-evaluation of nutrient reduction progress focused on rivers that have "tributary strategies" - river-specific nutrient reduction plans - in place. Tributary strategies for the James, York, Rappahannock and other Virginia rivers south of the Potomac have not been completed.

Excluding those rivers, the nutrient reduction goal actually becomes about 50 million pounds a year - or about 14 percent of all nitrogen entering the Bay.

Through 1996, the Bay Program estimated that wastewater treatment plant upgrades and runoff control efforts were enough to reduce the amount of nitrogen entering the Bay by 29 million pounds in an average year - a reduction of about 8 percent.