INDIANAPOLIS, AUG. 15 -- In the final day of competition at the Indiana University Natatorium, U.S. swimmers finished their record-setting Pan American Games deluge by sweeping gold medals in all six events and winning three of six silver medals as well, one by Michelle Griglione of Alexandria.

The U.S. team broke a Pan Am Games record by winning 27 of 32 possible gold medals, considered a significant feat since this was the U.S. B team. The A team is at the Pan Pacific championships. In all, U.S. swimmers won 27 golds, 20 silvers and 10 bronze medals. In the process, they beat bone-weary Costa Rican sensation Silvia Poll twice today.

But Poll, who won three gold medals here earlier in the competition, broke the U.S. hold on first and second place with two of the non-U.S. silver medals -- in the women's 50-meter freestyle and women's 200-meter backstroke. The other came in the men's 400-meter medley relay. The U.S. team won in 3:43.65, followed by Canada in 3:49.77 and Brazil in 3:50.29.

Poll, who won eight medals here this week and swam 13 races, including heats, said she was "very tired" and allowed that swimming two races in one day "maybe" was a mistake. But she also said her coach had wanted her to swim four more races here to "get as many medals as possible for Costa Rica.

"I would have won medals in those, too," she said.

Griglione won a silver medal in the women's 200-meter butterfly, losing to Kara McGrath of Birmingham, Mich. McGrath won in a time of 2:12.54; Griglione was second in 2:15.03.

Griglione, a 1986 graduate of T.C. Williams High School, led after the first 50 meters, but lost her lead to McGrath in the next 50 meters and never challenged her again. Shay McNicol of Canada won the bronze in 2:17.78.

Last year, Griglione had the second-best time in the world in the 200-meter individual medley and third best in the world in the 400-meter IM. But she said she gained about 12 pounds in her freshman year at Stanford University, and also had trouble adjusting to a different, more sporadic training schedule. By the U.S. Nationals two weeks ago, Griglione, 18, had lost about 10 of those excess pounds but still finished sixth in both the 200 and 400 medleys.

"It was a fiasco," she said today.

Griglione said she has decided not to go back to Stanford for her sophomore year this fall, but will stay at home in Alexandria to work out at the YMCA across the street from her home and get back in shape to try to make the U.S. Olympic team next year.

"I'm not going to give up," she said. "If this had to happen to me, this was a perfect year for it to happen. From now to next August, I plan to work hard to have things fall into place once again."

In other races, Bill Stapleton of Edwardsville, Ill., won the men's 200 individual medley in 2:03.58. Paul Wallace of the United States was second in 2:04.92. Ricardo Prado of Brazil was third in 2:04.94.

Jennifer Thompson of Dover, N.H., won the 50-meter freestyle in 26.09, a Pan Am record. Poll was second in 26.32; Jeanne Doolan of the United States was third in 26.34. Poll was beaten in the 200-meter backstroke by Katie Welch of St. Louis. Welch's winning time was 2:13.65, a Games record. Poll was next in 2:14.18, followed by American Holly Green in 2:14.75.

Alex Kostich of Belmont, Mass., also set a Pan Am record in the men's 1,500-meter freestyle, winning in 15:20.90 -- more than three seconds off the old mark held by Brian Goodell. Lars Jorgensen of the United States was second in 15:24.09 and Chris Chalmers of Canada was third in 15:30.51.

A footnote to the U.S. domination of the swimming events is that every member of the U.S. team won at least one medal.