Despite making progress in restoring Chesapeake Bay, the multistate cleanup effort is falling short of its major goal of reducing the bay's nutrient pollution 40 percent by 2000.
Preliminary projections presented yesterday at a bay cleanup meeting show that Maryland, Pennsylvania, Virginia and the District of Columbia appear likely to meet their goal of reducing phosphorus, one of two key nutrients fouling the Chesapeake.
But unless the cleanup pace quickens dramatically, the projections show that current efforts to reduce the other nutrient, nitrogen, will fall 28 percent short of the goal set a decade ago.
Officials have warned for some time that the cleanup campaign may not achieve the 40 percent reduction in nutrient pollution by the deadline, which is just 3 1/2 years away. But the Environmental Protection Agency's projections, drawn from sophisticated, computer-generated mathematical models of how the bay works, are the first to confirm and quantify the shortfall.
At yesterday's meeting, at Anne Arundel County's Jug Bay Wetlands Sanctuary on the the Patuxent River, EPA and state officials began mulling options for accelerating or expanding nitrogen removal efforts. Among the proposals were upgrading more sewage treatment plants to remove nitrogen from wastewater, requiring reductions from factories discharging significant amounts of the nutrient and seeking reductions in the use of nitrogen-rich lawn fertilizers and de-icers.
The projections are tentative and likely to change, officials stressed, so no decisions are expected before this fall. But several expressed doubts about being able to close the nitrogen gap, projected to be 21 million pounds throughout the bay, unless the cleanup expands significantly.
"That gap is going to strain, and possibly overstrain, all the resources we have," said William Matuszeski, director of the EPA's Chesapeake Bay Program office in Annapolis. He said some pollution control efforts are approaching limits of available technology.
"We've got a gaping wound, actually," said Ann Pesiri Swanson, director of the Chesapeake Bay Commission.
The nutrient reduction goal, set in December 1987, is a cornerstone of the restoration effort. Studies show that the bay suffers mainly from an oversupply of nitrogen and phosphorus from sewage discharges, farm and suburban runoff and air pollution.
The two nutrients stimulate large growths of algae in the water, blocking sunlight needed by the underwater grasses that are nurseries for fish and crabs. When microscopic plants die, they also consume oxygen in the water, creating "dead zones" on the bay bottom where fish and shellfish cannot survive.
The amount of nutrients entering the bay has been reduced -- dramatically in the case of phosphorus -- in large part because of sewage plant upgrades and bans on the use of phosphate detergents. However, nitrogen is harder to control because it dissolves easily in rainfall and ground water and because it comes from a multitude of sources.
Some bay rivers are running clearer now because of cleanup efforts, and bay grasses have partly rebounded, but there has been no detectable improvement in the main bay.
The EPA's computer models figure that nitrogen needs to be reduced by 74 million pounds a year, from 353 million pounds estimated entering the bay in 1985. But even with efforts to remove nitrogen at sewage plants and to curb fertilizer use on farms, the models project 312 million pounds of nitrogen still will be washing into the bay 3 1/2 years from now.
Phosphorus control efforts are likely to exceed their goal, projections show. The models predict that phosphorus will be reduced to 17.7 million pounds a year by 2000, from 27 million pounds entering the bay in 1985. That level is better than the 40 percent reduction goal of 18.6 million pounds.
But the EPA's forecast of success with phosphorus was dampened because the computer bay models also showed that the nutrient reductions are being rapidly undermined by the region's population growth and development. More people produce more sewage to be treated, more air pollution and runoff.
"We're fighting growth every step of the way," said Lewis Linker, the EPA scientist who presented the computer model projections.
The culprits: An over-supply of nitrogen and phosphorus.
Where they come from: Sewage discharge, fertilizer runoff and air pollution.
What they do: Stimulate algae growth, which blocks sunlight needed by underwater grasses that shelter fish and crabs. Dead algae also consume oxygen.
Pub Date: 4/26/97