Vanessa Hudgens is under investigation for allegedly defacing precious Arizona rocks on Valentine's Day.

The 27-year-old actress and boyfriend Austin Butler reportedly carved their names into a red rock formation outside Sedona, Ariz., where they spent the weekend. Sources told TMZ the Red Rock Ranger District of the Coconino National Forest is investigating.

Hudgens shared a photo of the carving on Instagram but has since deleted the picture. Federal law prohibits anyone from "damaging natural surfaces or property of the U.S.," and the formation in question is on U.S. land. She and Butler face a maximum $5,000 fine and/or six months in jail.

A Coconino National Forest spokesperson told ABC 15 visitors etching rocks is a "common" and "challenging" problem. Laws to protect the rocks are difficult to enforce since the person usually needs to be caught in the act to prove responsibility.

Hudgens left other photos from her trip up on Instagram, each captioned with "#sedonadreams." She and Butler have been together since 2011 and previously took a road trip through Arizona and New Mexico over the summer.

Hudgens is best known for playing Gabriella in the "High School Musical" movies and recently portrayed Rizzo in Fox's production of "Grease: Live!."

Butler played Sebastian on "The Carrie Diaries" and will star as Wil on MTV's adaptation of "The Shannara Chronicles."