There’s the story of the woman who is perfect except for a small birthmark on her face. Her husband insists that she go to a doctor to have it removed. Just as soon as the procedure is complete, she disappears. The world can’t handle perfection. On record and on stage, there are times that the harmonies of Tres Chicas are so gorgeous, so stunning, there should be genuine concern that the threesome will vanish.

From the trio’s earliest shows, it was clear that Tres Chicas would be more than just a passing phase for Lynn Blakey, Caitlin Cary and Tonya Lamm. It’s also always been clear that a Chicas show is a blast for everybody involved, those on the stage and those creeping ever closer to soak in the good vibrations.

“I guess people who come to hear us can expect a rootsy rock band driven by three women passionate about singing together and by lovely and soulful harmonies,” Blakey offers when asked about the Chicas experience. “Along with a few bad jokes from me, some tears, laughter, and the occasional bad word or spilled drink–depending on whether they’re free.”

When the name Sally Spring comes up, Blakey seems set to welcome the fellow Carolinian into the Chicas fold. “[She’s] a jewel of a singer, a North Carolina treasure, really. Her voice is rich enough to fund a small nation. We love her.”

Spring, a well-known performer on the Los Angeles and New York folk-rock circuit in the late 1970s and on into the ’80s, drifted away from that scene and toward bluegrass and old-time music, trading in clubs for chicken stews, churches, reunions and live radio shows. But her realization a few years ago that she had a backlog of songs she’d written and not recorded, along with the desire to work with some old friends (including Gene Parsons, Television’s Fred Smith, and longtime Joe Jackson bassist Graham Maby), lured Spring back into the studio. The resulting Mockingbird is a dangerously close-to-perfect kindred spirit to Tres Chicas’ Sweetwater and Bloom, Red & the Ordinary Girl.

Tres Chicas and Sally Spring play The Pour House on Monday, July 3. Doors open at 7 p.m., and the music starts at 8. Tickets are $8 in advance and $10 at the door. For more info, see www.treschicas.org or www.sallyspring.com.