When Cathy Kenworthy was 7, she tried out for the Lake Newport summer swim team in Reston. But after failing to make it across the pool, she was cut from the team.

Last night, the 15-year-old sophomore from O'Connell High didn't just finish the 400-meter individual medley at the Potomac Valley Swimming Senior Long Course Championships at George Mason University -- she won it. She also qualified for the junior nationals with a time of 5 minutes 3.26 seconds.

Other notable winners included All-Met Swimmer of the Year Jessica Brosch (Stone Ridge), who swam 2:07.28 in the women's 200 freestyle and former All-Met Ace Tate (Quince Orchard), who clocked a 57.58 in the men's 100 butterfly. Langley All-Met Lindsey Ertter won the women's 100 breaststroke in a time of 1:13.10. She qualified for the senior nationals and was .11 seconds off the Olympic trials mark.

Kenworthy, who swims for The Fish swim club in Fairfax County, rode the water well last night in the 400 IM. After getting off to a slow start in the butterfly, she moved into third with a 1:18 in the backstroke. She took the lead in the breaststroke and swam a 1:08 in the freestyle, beating the nearest competitor by more than four seconds.

"I'm not great at any one stroke, but I do all four strokes pretty well," said Kenworthy, who swam a 5:06.21 in the preliminaries and was seeded fourth in the final. "I'm always behind after the butterfly because I'm not too good, but I usually catch up in the breaststroke and blow them out of the water. Then I just hang on in the freestyle."