Yi shot 1-under-par 70 on Wednesday to finish at 5-under 137 with Dambaugh, who closed with 64 at Charleston Country Club.
Strom Thurmond High’s McKenzie Talbert tied for fifth at 71-73-144 while Aiken’s Taylor Ann Dodd shot 72-74–146.
Bryce Howell, of Blythewood, S.C., won the boys title. He shot 69-68–137 to beat four players by a shot.
Aiken’s Hayden Ploeger shot 74-74–148, Augusta’s Carson Spears had 71-77–148 and Aiken’s Ryan Carpenter shot 78-75–153.