To hear Amy Ray tell it, Justin Vernon might be a little off his rocker.

“But we’re very flattered,” the Indigo Girls co-founder quickly added with a laugh.

Ray and her musical partner of 30 years, Emily Saliers, learned a few years ago that Wisconsin’s Grammy-winning Bon Iver bandleader and indie-cool tastemaker is a major fan of the activist folk duo.

Vernon is so into the Indigo Girls, in fact, that he not only booked them alongside the likes of Boys Noize, the National and Doomtree at his inaugural Eaux Claires Music & Art Festival, but also asked them to perform their 1994 album “Swamp Ophelia” in its entirety.

“It’s my favorite album of all time,” Vernon emphatically told us. “And they’re still probably my favorite act of all time. I’ve never let up on them. I’ve never needed a fashionable reason to like them. I find them to still be highly underappreciated.”

Talking by phone a week ago from a tour stop in Mobile, Ala., Ray said she and Saliers are excited by the prospect of playing to “the cool kids” July 18 at the festival in Vernon’s native Eau Claire, Wis. “We don’t get asked to the Lollapalooza and Coachella kind of festivals anymore,” she said.

By sharp contrast, the duo will also perform to their faithful Twin Cities flock in the more familiar confines of the Minnesota Zoo the night before, July 17. (“We love everything about that place — except the bugs.”)

Between now and then, Ray said, they will probably rehearse one song per day from “Swamp Ophelia” with their band to be ready for the special Eaux Claires gig. Only about five of the album’s 11 songs have remained part of their live repertoire.

And therein lies the part that had Ray laughing.

“It’s not one of my favorites,” she admitted. “Swamp Ophelia” featured the Sailers-penned single “Least Complicated” but otherwise wasn’t a critical or commercial hit.

“Emily has some really strong material on that album that has held up well, but I certainly don’t think it has my best work on it,” Ray said. “In the context of playing the album in its entirety, though, the songs fit in and hold up just fine.

“It’s very much a prototype Indigo Girls album. There’s a certain amount of fans in the same age range as Justin who really latched onto it, maybe as a moment-in-time sort of thing, which is wonderful.”

Indigo mothers

Eaux Claires aside, Ray and Saliers are out on the road this summer concentrating on their first album in four years, “One Lost Day,” a travelogue-like collection of songs with such titles as “Texas Was Clean,” “Olympia Inn” and “Alberta.”

“We didn’t plan it that way, but geography is inherently a big part of the life that Emily and I share,” Ray said.

Both Georgia natives who still live near Atlanta, Ray and Saliers shared a seismic shift in their personal lives recently, which explains why this record was a longer time coming: They each became mothers.

Saliers and wife Tristin Chipman welcomed daughter Cleo in February 2013. Ray and her partner, screenwriter and music teacher Carrie Schrader, also had a girl, Ozilline, in November 2013 — sadly, just 10 days after Ray’s father died.

“It was such a riveting time in my life,” she recalled. “If anything, it made the solace of music all that more poignant and important in my life.”

However, she said, she learned not to let music take charge when it comes to juggling career and parenthood.

“We do shorter tours now, usually just two weeks out. And we do our writing in shorter spurts, too. When I’m at home now, I’m at home in the moment. I make sure I have three hours to spend playing with a toy horse, or whatever, because that’s as important to me as it is to her.”

Longtime LGBT advocates, among many other causes, Ray said she and Saliers are fine being labeled a “lesbian folk duo” nowadays after years of not wanting to be typecast. “It’s not used in the derogatory way it was” when they came to fame with the 1989 hit “Closer to Fine,” she said.

“We’ve been around so long, things have changed a lot in that time, especially over the last few years. We’ve seen things change and barriers being broken down just within our own audience, among the fans who’ve been with us all along. That’s been beautiful to see.”

As for the new audience members who will face the Indigo Girls for the first time at Eaux Claires, there’s more to be learned here besides the fact that the Bon Iver dude is very into them.