Ani DiFranco performs during the 2019 New Orleans Jazz & Heritage Festival 50th Anniversary at Fair Grounds Race Course on May 3, 2019 in New Orleans.

Two mighty musical women from two different generations of activism -- Ani DiFranco and Mavis Staples -- headlined the opening day of the Great Hudson River Revival Saturday (June 15) to benefit Pete Seeger’s environmental sloop Clearwater, which the late folk icon launched 50 years ago to save the river.

But at the event, aka the Clearwater Festival, a young woman from a third generation -- 14-year-old climate activist Alexandria Villaseñor -- briefly commanded the stage to urge the audience to join a worldwide global strike in September to save the planet.

“In December 2018, I began my weekly school strike in front of the United Nations headquarters demanding action [on climate change] from world leaders,” Villaseñor said told the crowd at Croton Point Park, on the shores of the Hudson, some 30 miles north of New York, as she credited the influence of Sweden’s Greta Thunberg, now 16, the leader of a global movement of student climate activists.

After months of demonstrations by students, Villaseñor told the crowd the movement’s young leaders last month called for “a general climate strike, adults and youth, on Sept. 20, which is the Friday before world leaders arrive in New York for the United Nations climate summit.”

The two-day Clearwater Festival -- Railroad Earth and the Wailers are Sunday’s headliners -- is a fundraiser for the Clearwater, a 106-foot-long wooden replica of a Dutch sailing vessel, which Seeger launched 50 years ago on May 17, 1969. (Seeger died in 2014 at the age of 94, predeceased by his wife Toshi Seeger, who originated the festival and passed away in 2013).

The most enduring activist organization with its roots in music, the Clearwater is widely recognized for its role in the decades-long cleanup of the Hudson, for its advocacy of environmental and social justice campaigns and for its education programs to train a new generation of environmental activists.

So the circle was unbroken as Villaseñor came to Clearwater stage to declare: “We’re sending a message to the world that we won’t stop until action has been taken to save our planet.”

Stephen D. Smith, the president of the board of the Clearwater, in a letter to festival attendees, wrote that the organization “is making this year’s celebration a true revival -- a return to our roots of activism and advocacy.”

The weekend, which also celebrated the centennial of Seeger’s birth on May 3, 1919, began as supporters set sail on the Clearwater Friday evening for a singalong on the Hudson led by Tom Chapin and his daughters, Abigail and Lily, who perform as the Chapin Sisters.

Acknowledging sloop’s five-decade history, those aboard included Allan Aunapu, who was captain of the Clearwater on its maiden voyage in the summer of 1969, and Andy Wallace, a musician and crew member on early sails.

On Saturday morning, Tom Chapin opened the festival with a set billed as “Remembering Pete Seeger,” which featured many performers who have been mainstays at the event. Among them was Native American singer/songwriter Joanne Shenandoah, a reminder of those who were stewards of the Hudson Valley for generations before European settlers arrived in the 17th century. Joel Rafael sang Seeger’s “Sailing Down My Golden River.” Mike Merenda of the Mammals introduced Seeger’s “Quite Early Morning” as the last song the singer played days before his death.

“Don't you know it's darkest before the dawn/ And it's this thought keeps me moving on/ If we could heed these early warnings/ The time is now, quite early morning.”

This year’s festival was the first organized by director and producer Jason Samel. “I feel so honored to carry on this beautiful tradition,” he told the crowd Saturday before the opening set.

Kitama Cahill-Jackson, a grandson of Pete and Toshi Seeger, said, “every single year at this festival, I feel like my grandparents come alive again. It’s been five years since they passed. They created this organization. My grandmother, Toshi, created this festival and everything you see here. And it’s such an honor to see each and every one of you continue their legacy.”

With some 90 artists performing on eight stages across the two days, the Clearwater Festival reflected Pete Seeger’s embrace of songs from all cultures.

“The Clearwater, of all festivals, celebrates all musics and values that are meant to last,” said David Amram who, at 88, is one of Seeger’s contemporaries and returns to perform each year.

The choice of DiFranco and Staples to headline Saturday was inspired. Like Seeger, both performers have shown the power of songs to advance social change, from the civil rights movement and gun control (Staples) to LGBTQ+ rights and reproductive freedom (DiFranco).

“I couldn’t be happier being here; It’s always like a homecoming at Clearwater,” said DiFranco, who first performed at the festival in the early 1990s and as recently as last year.

On acoustic guitar, DiFranco played with propulsive, engaging energy that was irresistible. Among the highlights of her set was a song written in the 1930s by Florence Reese, the wife of a union organizer in the coal mines of Kentucky, revived by Seeger in the 1960s, and rewritten by DiFranco for a recording in 2012.

“We need this song more than ever,” said DiFranco, launching into her electrified version of “Which Side Are You On?”

As clouds moved in over the Hudson River on the horizon, Staples took the stage to the soulful vamp of the Staples Singers’ 1973 top 10 hit “If You’re Ready (Come Go With Me)” followed by “Slippery People” from the Talking Heads. She boldly offered new songs from her just released album “We Get By,” acknowledging they might be unfamiliar to many. But the crowd instantly recognized her version of Stephen Stills’ “For What It’s Worth.”

Staples’ set closed with “No Time For Crying,” which she co-wrote with fellow Chicagoan Jeff Tweedy and released in 2017, demanding action on gun violence killing young people. In her onstage comments, she also cast the song as a call for justice for immigrant children and their parents

“I get so tired of the way this man is treating our children,” said Staples, leaving President Trump unnamed. “Putting our babies in cages. We’ve got motherless children. I can’t stand it. I tell you what I’m gonna do,” said Staples to cheers from the crowd, “I just might run for president myself!”

Like young climate activist Alexandria Villaseñor, in her chorus of her closing song, Staples challenged the Clearwater audience. “No time for crying,” she sang, “no time for tears. We’ve got work to do!”