very Deadhead and those with an extended Monterey International Pop Fest education are aware that the members of the Grateful Dead weren’t happy with their Monterey Pop set. Lesh, who performs with the Terrapin Family Band (9:25pm Sunday) feels no differently. He refers to the Dead’s Monterey Pop performance as the “first example of blowing the big ones.”

“That’s the running joke throughout the Grateful Dead,” Lesh says. “Monterey, Woodstock and so on. While Monterey was career-defining for Janis, for Jimi and maybe some other acts, it was not for us.”

Lesh hasn’t ever listened to any of the available recordings of the Dead’s Monterey Pop set, but sticks with his gut feeling, which all the members have unanimously agreed was lackluster. They did deliver an undeniably smoking rendition of “Viola Lee Blues.”

“It might not have been a bad show, but it wasn’t a great one,” Lesh adds. “I think we were just glad it was done. It happens. Just because it was one of the big ones, it doesn’t make a difference whether it was a not-so-great show in a small club.”

In 2017, Lesh helps keep the legacy of the Grateful Dead going with a laidback rotating group of musicians – Lesh is the one constant – that evolved from weekly shows at Lesh’s venue/restaurant/bar Terrapin Crossroads in San Rafael.

The Terrapin Family Band is the venue’s official house band that has had a roster of special guests sit in on a regular basis, including Bob Weir and Phish’s Trey Anastasio.

Lesh initially built Terrapin Crossroads as a spot where he would always have a stage to perform on, even when he wasn’t touring.

“The other side of the coin was I hoped [Terrapin] would replace touring altogether,” Lesh says. “I have a deal with [promoter] Peter Shapiro, where I come out and play at the Capitol [Theatre] or the Brooklyn Bowl – we’re focusing this year on the Terrapin Family Band and moving forward.

“I’m still traveling to perform, but it’s not a tour in that sense, so I’m focusing mostly on Terrapin Crossroads.”

TFB began strictly performing Grateful Dead-oriented sets, but Lesh says they’ve started working in some bandmembers’ original material, including his son Grahame Lesh’s work. (His band Midnight North recently performed Hipnic in Big Sur.)

Phil’s voice glows when the subject of performing music with his son comes up.

“I don’t think there’s anything better in the world for a musician,” he says. “[Grahame’s] voice as a singer and a guitarist is really unique, even though it sometimes feels like I’m performing with myself – we’re so connected.

“He continually astonishes me with the originality of his playing, and how he reacts to what the other musicians are playing. It’s just so gratifying. It makes me smile, and sometimes it makes me giggle out loud.”

Throughout the Grateful Dead’s tenure with Jerry, there are countless live moments, from a Fillmore East version of “Hard to Handle” to an epic “Dancin’ in the Streets” in San Bernardino, when Lesh’s bass line eases into hypnotic riffs that represent the song’s peak.

“Those things were always spontaneous,” he says. “The music shows you what needs to happens, and it’s a split-second kind of thing – all of the sudden, [the music] rises to a peak, and there’s going to be a change after this peak, so you want to play something different.”

Lesh adds that the aforementioned feature is something that occurred with all the members of the Dead, and continues to occur with the Family Band.

“It’s part of the nature of the music and the way we approach it, which is totally open,” he says. “That was the idea with the Grateful Dead from the beginning: We never wanted to play a song the same way twice. We didn’t want to go out live and play the record.

“That was the way we were going to do our music no matter what anybody thinks.”

The Grateful Dead, before Jerry died, played over 2,400 concerts.

“The members of the Grateful Dead are not even there,” Lesh says. “The music is driving all of us at the same time, in the same way. That’s the highest you can get playing music, so it’s impossible to pick out a favorite show. Those high points are what stick with you. That’s what you want to re-create in the next show; there are ideals that you can aspire to.”

Phil Lesh will return to Central Park in New York on Aug. 30 for a Summerstage show with the Terrapin Family Band and special guests Melvin Seals of the Jerry Garcia Band and folk rocker Nicki Bluhm (see more on Bluhm, who also plays the festival this weekend, p. 8).

Lesh’s Grateful Dead bandmate Bob Weir has been touring as Dead & Company, featuring Weir, original Dead drummers Mickey Hart and Bill Kreutzmann and modern-day rocker/heartthrob John Mayer on lead guitar and co-vocals.

“I think the more Grateful Dead music that’s out there, the better,” Lesh says of Dead & Company. “I think those guys are doing a great job, they’re having a lot of fun and playing big places – I think it’s absolutely great.”

MONTEREY INTERNATIONAL POP FESTIVAL 50 Noon, Friday June 16, Saturday June 17 and Sunday, June 18. Monterey County Fairgrounds, 2004 Fairgrounds Road, Monterey. $105/one day; $295/three-day pass; $450/three-day bleacher; $695/three-day VIP. montereypopfestival50.com