Last year, James L. Woltz estimated that Fox Island would sell for $2.5 million, right before his Virginia-based real estate firm auctioned the property for $3.6 million.

This summer, as Woltz & Associates Inc. prepares to auction off about 515 acres of prime north country land, Mr. Woltz is not making any predictions.

"Multimillion-dollar sale" is the most he will say about the prices he expects to see when multiple properties in Cape Vincent, Clayton and Henderson Harbor go up for sale Aug. 30.

The auction will be held at the Clayton Opera House, 403 Riverside Drive, at 11 a.m. As with the Fox Island sale, Schrader Real Estate and Auction Co. Inc., Columbia City, Ind., will be the auctioneer.

"I think we're going to have us a great sale," Mr. Woltz said when reached at his office in Roanoake, Va., last week.

One of the attractions, he said, is that the properties up for bid in August are extremely diverse, ranging from undeveloped waterfront land to an 1820s farmhouse and a contemporary home built in 2003.

The listings, which already have begun to appear on the Woltz & Associates Inc. Web site, read like a who's who of trophy properties.

They include the Clayton home of Mary T. and Morse G. Dial; the Clayton residence of Ted and Mary M. Mascott; 100 acres of land on Hardscrabble Point in the town of Lyme owned by the heirs of John W. and Mary Jane Logan; the Logans' Burnt Rock Farm, Cape Vincent; the Cape Vincent residence of Mr. and Mrs. Kevin Rowe, and the residence of Elizabeth B. "Lee" and William C. Couch Jr. on Route 123, Henderson Harbor.

All of the various owners approached the Virginia firm in the aftermath of the Fox Island sale, Mr. Woltz said. Vance J. Wilson, New Jersey, purchased Fox Island for $3.6 million, plus a 5 percent buyer's premium, for a total of $3.78 million.

"These are going to be as intriguing as Fox Island was," he said. "They're fabulous properties."

What makes the August auction fairly unusual, and correspondingly hard to predict, is the open, mix-and-match format of the sale. Large properties have been carved up into smaller pieces that can be bid on separately or in conjunction with other auction parcels.

"Any purchaser will be able to group any of these together in any configuration," Mr. Woltz said. "At the end of the day, we will sell the property by whatever combination yields the highest dollar."

DIAL RESIDENCE

In the case of the Dials' residence, which is being sold in conjunction with Exit More Real Estate, a villa with 23 acres can be purchased with or without a garden house and 3.7 adjoining acres, Mr. Woltz said. The suggested opening bid for the entire property is $1.5 million.

Cheryl Beecher Zeldin, one of a trio of Exit More Real Estate agents who originally listed the Dial residence last August for $5.8 million, said she expected the auction to attract buyers beyond the reach of her agency.

"We sent out marketing fliers, but as a local agency here," she said. "You really have to be with a huge company to be able to market this in huge cities."

Ms. Zeldin said the Exit More agents suggested that the Dials try the auction route. The real estate agency will receive a cut of the final sale, which Ms. Zeldin estimated to be 3 percent.

The Dials also are auctioning 240 acres of land between Route 12E and Pelo Road. There is a conservation easement on the property, held by the Thousand Islands Land Trust, but Mr. Woltz said the easement permits some construction.

"The easement was nicely done so it allowed places people could build homes," Mr. Woltz said. He expects to list the property as five different tracts, ranging from 20 to 100 acres.

Potential buyers "can bid on each individual piece or combine them with the main house on the St. Lawrence," Mr. Woltz said. "We don't restrict what combination somebody puts together to buy the land."

MASCOTT PROPERTY

For even more elbow room, a bidder could throw in the neighboring 15.6 acres of Mascott property in Clayton. The Mascott home includes 5 bedrooms, 41/2 baths, a mahogany-paneled library, a modern kitchen, a 1,900-bottle wine cellar and a 60-foot-long stone terrace overlooking the St. Lawrence.

The property, also known as Lion's Head, is being sold in conjunction with Realty USA, Clayton.

Across Route 12E, the Mascotts are auctioning off a 33.8-acre parcel beside the Dials' 240-acre conservation area.

None of the land along Route 12E has a reserve, the lowest bid for which a property can be sold at auction. In contrast, the Dial and Mascott residences have reserves that Mr. Woltz described as "extremely realistic, very achievable reserve numbers." He declined to name the figures.

"There's no way anybody could reproduce what's there with anywhere close to what the reserves are," he said.

LOGAN PROPERTIES

On Lake Ontario, 100 acres of Hardscrabble Point near Three Mile Bay will be up for sale. The property includes 3,300 feet of shoreline frontage, looking out to Fox Island, and a little cottage called "The Shack" by the Logan family, Mr. Woltz said.

He said the 100 acres of developable land may be sold as six tracts, ranging from 1.3 to 49.6 acres. The Logan land also comes with a reserve.

Burnt Rock Road Farm, another Logan property, is up for auction as well. The 90 acres include a 4,000-square-foot stone house with six bedrooms and 21/2 baths that was built in 1824 and a barn.

The farmhouse, which has since been renovated and has no reserve, is being sold in conjunction with Hefferon Real Estate, Watertown.

ROWE RESIDENCE

The contemporary home is on Fuller Bay Drive, Cape Vincent. Mr. Woltz said the 4,700-square-foot Rowe residence, built in 2003, includes about 3/4 of an acre of land and 160 feet of frontage on Lake Ontario. It has four bedrooms, 31/2 baths and a view of Tibbetts Point Lighthouse.

The house has a suggested opening bid of $499,000.

COUCH RESIDENCE

The final listing is the Couch residence, which was added to the auction Monday. Mr. Woltz said the Henderson Harbor property was under contract to be sold until last week, when a contract contingency was not met. The Couches already had been in preliminary discussions with his firm and so were able to meet the deadline for the auction and the accompanying brochure. The Couch property was the final addition, Mr. Woltz said, as there was no longer time to prepare a new property for the August auction.

The 3,200-square-foot residence was built in 1878 and features 5 bedrooms, 11/2 baths, three barns and an outbuilding that was originally a decoy shop. The property has 7.9 acres of land with 153 feet of frontage on Lake Ontario. Mr. Woltz described the lawn, which slopes down to the water, as "just gorgeous."

The property, which is being sold with a reserve, has a suggested opening bid of $650,000. It is being sold in conjunction with Katherine R. Couch of Exit More Realty, who had listed the property for $815,000.

Over the coming month, Mr. Woltz's firm will launch an advertising campaign to reach out to buyers in the Eastern United States, Europe and Canada. He expects the collective auction to attract a wide range of buyers.

"You've got a real broad menu of properties. It just depends on who shows up at the sale," he said. "Our job is to get the most money we can for these sellers."

Mr. Woltz is off to a good start. Last week, shortly after listing the first property, he received an e-mail from a buyer in Scotland who, having heard of the Fox Island auction, wanted to learn more about the Clayton home.