EXCLUSIVE: Denise Richards is staying on blue. The Blue Mountain State star has joined the cast of the Lifetime movie Blue Lagoon, a the coming-of-age love story and remake of the 1980 romance/adventure movie starring Brooke Shields and Christopher Atkins. The telefilm, distributed by Sony TV, stars young Australian actors Indiana Evans and Brenton Thwaites as classmates Emma and Dane, who become marooned on a tropical island. Richards will play Barbara Petersen, a successful and devoted mom who tirelessly searches for her daughter. Additionally, Atkins is returning for a cameo in the film executive produced by Neil Meron, Craig Zadan and Judith Verno. Richards, repped by ICM and KLWGN, just wrapped a starring role in Tyler Perry’s Medea’s Witness Protection and has been recurring on 30 Rock. Atkins, who earned a Golden Globe nomination for his role in the original Blue Lagoon, is about to film the indie Unbelievable. He is with Don Carroll Entertainment.