Developers announced plans yesterday for a large hotel and conference center to be built on an environmentally sensitive bluff overlooking the Potomac in Prince William County.

The $50 million project would be the county's first full-service hotel. Currently, county organizations such as the Chamber of Commerce have to travel to Fairfax County to hold annual dinners and other ceremonies.

The announcement is the latest example of upscale development in a county that used to be considered a mecca for used cars and outlet shopping. Over the past decade or so, Prince William has emphasized high-end development. The county is now home to numerous houses boasting $1 million price tags, and plans are in the works for gourmet markets and Jaguar dealerships.

"It's another sign that Prince William is becoming an attractive location for every sort of business investment," said Sean T. Connaughton (R), chairman of the Board of County Supervisors and a supporter of the project.

The developer, Vienna-based KSI Services Inc., said plans call for a 272,000-square-foot facility with 234 hotel rooms, banquet and meeting halls, and spa, fitness and recreation areas. An 18-hole golf course designed by Jack Nicklaus is also being planned.

A KSI spokesman said the company is negotiating with several upper-end hotel chains to operate the facility but declined to say which ones.

The architects, Hellmuth, Obata + Kassebaum, said in a statement that the design will be "in the great tradition of the 19th-Century railroad hotels, which were set against majestic landscapes." The architects have designed waterfront hotel and conference centers in London; Jakarta, Indonesia; and Abu Dhabi, United Arab Emirates.

The hotel is the centerpiece of the 1,700-acre Harbor Station development with 2,500 homes, 2 million square feet of office and retail space and a "town center" with a Virginia Railway Express commuter station. It is being built on the Cherry Hill Peninsula, which is on the Potomac River east of Route 1 between Woodbridge and Dumfries.

Over the past few years, county leaders have drawn up ambitious plans for the Route 1 area, which they say is strategically situated for an economic rebirth that would replace tired strip malls and aging apartments with upscale and transit-oriented development, as well as affordable housing. The county is also counting on two new tourist destinations, the planned Belmont Bay Science Center in Occoquan and Quantico's Marine Corps Heritage Center, which is under construction. County planners see them as the keys to bringing thousands of tourists, economic development and, officials hope, some cachet to the Route 1 corridor.

The office space and employment opportunities at the hotel also play into plans to increase job opportunities in the county "so that people do not have to get on the roads to commute to their jobs," Connaughton said.

Prince William added jobs at the fastest rate of any big county in the United States in the year that ended in March, with an 8 percent rise, according to the Labor Department.

But development on the Cherry Hill Peninsula is not without controversy. Environmentalists say the slab of land along the river includes one of the last pristine forests along the Potomac in Northern Virginia. Cherry Hill was rezoned for thousands of homes and a town center in January 2001 after a divisive debate on the peninsula's future. The rezoning was marked by fervent opposition from a group of local and national environmentalists who said the site's unstable soil coupled with its hilly landscape would result in erosion and silt runoff into Powells Creek and the Potomac.

"It's a one-of-a-kind resource," said Kim Hosen, a member of the county's Planning Commission. "We're concerned about high-quality development, too, while making sure all of the processes are followed and protecting the health and safety of residents of Cherry Hill."

Developers hope to have all approvals in place in six months, with construction to start soon after.

The hotel and conference center are to be built on Cherry Hill Peninsula. A golf course designed by Jack Nicklaus is also planned.

Environmentalists worry that developing Cherry Hill Peninsula will ruin a pristine forest and cause silt runoff.