Hakop Kaplanyan, 18, was taken into custody after the alleged victim, who is also a UCLA student, reported the assault to campus police Tuesday morning.
Kaplanyan posted bail Wednesday morning. He was on suspension from UCLA pending an appeal. He is set to appear at the Airport Courthouse in Del Aire on April 25.
Kaplanyan's attorney told Eyewitness News that Kaplanyan was dating the girl and that the two had consensual sex. The attorney described the allegations as a "defamation" case and said that the investigation is incomplete.
On the UCLA athletics website, Kaplanyan is listed as a 6-foot-2, 205 pound red-shirt freshman who plays attacker on the water polo team, which is consistently ranked one of the top water polo programs in the nation.
While at Hoover High School, the website say Kaplanyan was twice named league MVP and set a CIF scoring record in 2009.
On Saturday, Kaplanyan tweeted, "These couple of days were like a dream."