What will be the tab for a restored Chesapeake? No one really knows how much the nutrient and sediment reductions will cost, but several estimates have been made.

The Chesapeake Bay Commission, which represents the legislatures of Maryland, Virginia and Pennsylvania, produced a report in 2003, “The Cost of a Clean Bay,” which estimated that it would cost slightly more than $10 billion to achieve current water quality goals by 2010.

The Bay Program has made a similar estimate—suggesting it could take about $1.1 billion a year from now through the end of the decade to achieve the goals.

Those figures come with an important caveat. They were based on the estimated cost of implementing a hypothetical mix of nutrient control practices that would achieve the nutrient reduction goals. The mix was not based on the cost-effectiveness of different nutrient control techniques; some disproportionately expensive nutrient control practices, such as retrofitting stormwater systems in older cities, have huge costs for small nutrient benefits.

Nor do the estimates take into account potential savings that may be realized from the development of trading programs, which allow sources that can control nutrients cheaply to sell “credits” to those for which nutrient controls are more expensive, as long as overall goals are met.

Also, some costs are conservative, worst-case, estimates. For instance, the Bay Program calculated wastewater treatment plant upgrades could cost $4.5 billion throughout the watershed. Already, a Maryland engineering study found that upgrades at that state’s plants would be 32 percent less than the Bay Program estimate. A recent study by the Hampton Roads Sanitation District in Virginia found that upgrades at its 8 facilities would cost 23 percent less than the Bay Program estimate.

The Alliance for the Chesapeake Bay, in a December report, “Chesapeake 2004: A Blueprint for Success,” indicated that currently available, cost-effective technologies could achieve 90 percent of the needed nutrient reductions.

Those included the use of state-of-the-art nutrient control technology, combined with trading programs, at wastewater treatment plants throughout the watershed. The report also called for full implementation of nutrient management plans on all farms, and widespread use of cover crops on croplands throughout the basin. The report did not give a total cost, but suggested it could be substantially less than other figures.

If such programs achieved 90 percent of the nitrogen goal, and proposed EPA air regulatory programs reduced nitrogen by another 8 million pounds as the agency has estimated, it would nearly achieve the Bay Program nitrogen goal.

On another financial front, the Bay Program in March will begin convening a “blue ribbon” panel aimed at identifying new sources of funding to help pay for cleanup efforts. It is to report its findings this fall.