ROSE HAVEN, Md. (AP) Maryland, Virginia and Pennsylvania signed an unprecedented agreement Wednesday to protect the Chesapeake Bay by slowing urban sprawl.

''This landmark agreement clearly recognizes that what happens on land directly affects the long-term health of the bay,'' Maryland Gov. Parris Glendening said.

The states pledged to reduce by 30 percent the rate of urban sprawl in the bay region by 2012. They also resolved to permanently protect 1.6 million acres around the bay and restore 25,000 acres of wetlands by 2010.

The accord was signed by Glendening; Gov. Tom Ridge of Pennsylvania; Gov. Jim Gilmore of Virginia; and Mayor Anthony Williams of Washington D.C.; and the Environmental Protection Agency.

Bill Matuszeski, director of the EPA's Chesapeake Bay Program, said the accord is the first multistate agreement to tackle sprawl on a regional level.

The effort to reduce sprawl was prompted by projections that an estimated 3 million people will settle in the bay watershed by 2020. The 64,000-square-mile watershed is already home to more than 15 million people.

The pact is a major overhaul of the last Chesapeake Bay agreement, signed in 1987.

While the new agreement commits the states to further reductions in levels of nitrogen and phosphorous, mostly from farm runoff, it will also focus on 3,600 species of plants and animals in the nation's largest estuary.

''The way we will judge our success is not by water clarity,'' said Peter Marx, a spokesman for the EPA's Chesapeake Bay Program, ''the standard will be how the living creatures respond.''

The agreement calls for a tenfold increase in the bay's oyster population by 2010, based on a 1994 baseline, when low numbers were recorded because of a ravaging parasite. A target harvest for blue crabs will also be set next year.

Environmentalists welcomed the agreement.

The accord improves on its predecessor by setting specific numerical goals, said Mike Hirshfield, vice president of the Chesapeake Bay Foundation.

The accord also calls on the three states to work to eliminate a loophole in the federal Clean Water Act that allows 100 industrial sites in the bay watershed to spew toxic chemicals into the bay and its tributaries.

Matuszeski said much of the credit for the commitment to reduce sprawl the most controversial provision in the agreement goes to Glendening, who has made his ''Smart Growth'' plan to concentrate growth in developed areas a centerpiece of his administration.

Gilmore, who has clashed with Glendening on growth issues, held out for six months, arguing that land-use decisions should be made locally and not be dictated by the state.

In the end, Gilmore agreed to sign after the sprawl provisions were changed to apply to the entire bay watershed, as opposed to the earlier call for a 30 percent reduction in each state.

On the Net: http://www.dnr.state.md.us/bay/index.html