Duke easily held off Purdue for its fifth team title in nine years, shooting a 2-over 290 to finish with an 18-over 1,170 total on LPGA International's Legends Course. Purdue finished at 33 over, a stroke ahead of third-place UCLA.
Lewis, six strokes behind Purdue's Christel Boeljon after a third-round 74, shot a 6-under 66 -- the best round of the tournament -- to beat Boeljon (76) and Southern California's Paola Moreno (71) by four strokes.
Lewis, a junior from The Woodlands, Texas, birdied the first five holes on the back nine to pull away. She finished at 6-under 282.
Duke's Amanda Blumenherst (72) finished fourth at 1 over, UCLA's Tiffany Joh (72) followed at 3 over, and Duke's Anna Grzebien (70) was 4 over. Duke's Jennie Lee (74) and TCU's Catherine Matranga (77) tied for seventh at 6 over.
Southern California finished fourth in the team standings at 44 over, followed by Stanford (45 over), Vanderbilt (48 over), Pepperdine (50 over), Georgia (53 over), Auburn (61 over) and Louisville (62 over).