In the middle of his annual rafting trip down the Black River, William A. Clifford, a car salesman from Rochester, suddenly found himself flying headlong into the surrounding rapids.

A long summer of rain meant the river was high and swift for the Aug. 16 trip, which included Mr. Clifford's girlfriend, his son and his son's friend.

After one particularly hefty rapid, six of the nine people were heaved out of the boat, leaving only Mr. Clifford's son and their Hudson River Rafting guide.

Mr. Clifford was delighted.

"It's a lot more enjoyable with the higher water — a little rougher, a little bit more intense," he said. "If it could be like this every year, it'd be great."

Owners of the four rafting companies that offer trips down the Black River said this week that higher than normal river levels during the summer have created a buzz among customers. With attendance already above last year's levels, owners of Adirondack River Outfitters, Whitewater Challengers, Hudson River Rafting Co. and B.O.B. Rafting say that the large rapids have raised expectations for next season and beyond.

"It's been really spectacular," Kenneth E. Powley, president of Pennsylvania-based Whitewater Challengers, said. "I think it has generated an awful lot of very positive word of mouth from folks that took the trip earlier in the season at great water levels."

So far this month, 3.54 inches of rain have fallen in Watertown, compared to the normal 2.29 inches, according to figures from the National Weather Service in Buffalo.

Since the first of June, 10.94 inches have fallen in Watertown, well above the normal 7.61 inches. Last year at this time, only 5.88 inches had fallen.

With so much rain flowing into them, the rivers' levels have risen. Last week, the U.S. Geological Survey reported that the Black River was discharging roughly 9,000 cubic feet per second.

That level had started to come down this week, but on Aug. 25 the Black River was measured at 3,780 cfs, still well above the 1,720 cfs average.

"Every water level has its different attributes," said Robert V. Peterson, who owns B.O.B. Rafting, Watertown, with his wife, Suzanne M.

Low water levels typically mean more rocks to maneuver around, creating a more technically challenging trip, while high water creates larger waves and faster water, Mr. Peterson said.

"I think most customers come here with the attitude to have a good time," he said, adding that "big water waves are a little more exciting."

"We all like to see high water," Gary J. Staab, owner of Adirondack River Outfitters, Old Forge, said. "I think everyone is pretty satisfied with the season so far."

As well as the Black River, Hudson River Rafting and Adirondack River Outfitters operate on the Hudson, Moose and Sacandaga rivers. Whitewater Challengers covers similar ground, but substitutes the Salmon River for the Sacandaga. B.O.B., the smallest of the companies, concentrates on seven miles of Black River.

Mr. Staab said his company has been telling customers about "superb" conditions this year on all of the trips they offer.

"We encourage people to go and tell them the rivers are running great," he said. "There are great river levels this time of year."

Patrick J. Cunningham, president of North Creek-based Hudson River Rafting, said customers are often attracted to the so-called "high adventure" trips, which are created by high water levels.

Typically, the largest rapids will occur in the spring, when rivers are swollen with snow melt. This year, the rivers have retained their large rapids through the normally drier summer months, he said.

"Here it is summer and we should have low water, but we don't," he said. "It's extremely high now, so it's high adventure — and it's warm water."

Mr. Cunningham estimated attendance was up 11 percent to 15 percent for the season, which runs from May 15 to Columbus Day. The company also saw attendance increases at their sites on the Hudson, Moose and Sacandaga rivers, he said.

"I think going into next year we're going to get a very positive return from people who went and had a very good time," Mr. Cunningham said.

Mr. Powley, of Whitewater Challengers, estimated the higher water had increased the difficulty of the rapids by half a step, turning rapids that are normally class 3 or 4 into class 4 and easy class 5. In the scale of rapid difficulty, class 1 requires no skill to maneuver and class 6 means the river is essentially impassible, with rapids potentially causing serious injuries or death.

"People who sign up for the Black are really looking for an adrenaline rush," Mr. Powley said. "Not that it's not there at lower water, but when it's high it exceeds expectations. That's a good thing."

This summer, during the company's busiest day, Whitewater Challengers took 210 people on about 30 rafts down the Black River. Mr. Powley said the daily average over the summer was roughly 15 to 20 rafts per day.

Word of mouth, which Mr. Powley said is always the best advertising a rafting company can get, helped increase attendance by 30 percent to 40 percent over last year, he said.

"I expect it to be up again next year, with as many people as we've sent home with smiles on their faces," he said.

Mr. Clifford was so impressed with his trip he purchased a company video of the experience from Hudson River Rafting. After three years of traversing the Black River, Mr. Clifford said he's established a family tradition, one that he plans to continue in 2009.

"I definitely will be going back," he said. "I'm hoping the water is high up there and the experience is just the same as this year."