The Virginia State Water Control Board has endorsed proposals that would require sewage treatment plants to dramatically reduce the amount of pollution they release into streams and rivers that feed the Chesapeake Bay.

The proposals, estimated to cost as much as $1.1 billion, would target nitrogen and phosphorus discharges from wastewater treatment facilities. The pollutants are blamed for spurring the growth of algae in the bay, which in turn eats up the oxygen that crabs, fish and bay plants require.

The move comes as the U.S. Environmental Protection Agency last month proposed a federal effort to limit similar discharges from treatment facilities. New reports this summer also have shown that pollutant levels in the major rivers feeding the bay have shown no decline in recent years.

Virginia Secretary of Natural Resources W. Tayloe Murphy Jr. said reductions of the kind envisioned in the regulations are the only way Virginia can live up to its commitment to limit the amount of nitrogen dumped in the bay yearly as part of a regional effort to clean up the bay.

"I think the regulations are as important as any water quality initiative I have seen in the past 20 years of public service in Virginia," he said. "We know what we need to do to restore the bay. The question is finding the political will to do it."

Under the proposals, existing treatment facilities would be required to reduce nitrogen levels to 8 milligrams per liter, and new or expanded plants would have to drop levels to 3 milligrams per liter, considered the best modern technology will allow. Annual limits would also be set on major plants.

Industry experts say that most plants would need to add new equipment and capacity and introduce biological processes using microbes to gobble up nitrogen.

There is no limit on the amount of nitrogen released by sewage treatment plants, and many dump as much as 20 milligrams per liter of water, said Bill Hayden, spokesman for the Virginia Department of Environmental Quality.

The public will be invited to comment on the proposals before they are revised and officially adopted next year by the water control board, he said. At that time, treatment facilities will be required to reduce pollutant discharge to retain their operating permits, and officials hope all plants will be in compliance by 2010.

Environmentalists blame sewage treatment plants for much of the nitrogen that flows into the Chesapeake Bay. Nutrient runoff also comes from other sources, including agriculture, but restricting releases by municipal and industrial treatment facilities would be a "significant step" toward cleaning up the bay, said Chuck Epes, a spokesman for Chesapeake Bay Foundation in Virginia. He called such emissions "the big 800-pound gorilla of the bay pollution problem."

Epes said the foundation probably will push for legislation during Virginia's next General Assembly to help pay for the proposals, including a possible "flush tax" on sewage users, much like the one enacted in Maryland this year.

The regulations would probably cause sewer rates to rise, warned Christopher D. Pomeroy, an attorney for the Virginia Association of Municipal Wastewater Agencies.

In addition, he argued that the yearly pollution limits for Northern Virginia plants do not allow for population increases, especially in the fastest-growing localities.

"The trends show the population in the region outstripping the ability of even the most advanced treatment plants using the most advanced technology to live within those [yearly limits] set by the state," he said.

Murphy said, however, that the pollution limits took into account how much sewage treatment plants could achieve and do in fact allow room for population growth. He said he would anticipate hearing from operators who feel their cap is too low before the regulations are finalized.

"That's the reason for public comment," he said.