If you live in the Hudson Valley, you probably take certain regional treasures for granted just because they’ve been around for so darn long. Pete Seeger, for instance, is 92 now, and we’ve gotten used to him coming around to perform with little fanfare at our schools that it took a massive, star-studded 90th birthday bash at Madison Square Garden for many of us to sit up and take notice of how important he is to the whole musical planet.

Likewise, the magnificent sloop Clearwater has been plowing the waves of the Hudson for more than 40 years now, and a couple of generations of the Valley’s schoolchildren have gotten their first taste of what it’s like actually to be on the River – not just crossing over it on a bridge – and meeting the creatures who live in it while on field trips aboard her. And the Great Hudson River Revival, the oldest and largest annual music festival of its kind, has been happening every Fathers’ Day weekend for so long that it too can easily pass under the radar.

That’s a shame, for a couple of reasons: One is that festival ticket sales constitute by far the largest single funding source for the Hudson River Sloop Clearwater’s environmental education activities; a year with really bad weather on Revival weekend inevitably means a lean-budget year for the organization. Secondly, it’s an immensely talent-packed weekend, consistently drawing huge names from the folk/rock, singer/songwriter, Americana, blues, roots and world music genres. This year’s lineup is especially stellar, but we’ll get to those details in a minute.

The Hudson River Revival was originally conceived in the mid-‘60s as a series of “sloop picnics” scattered up and down the Valley: potluck affairs where everyone was encouraged to bring an instrument and sing together. Then Pete would talk a bit about the sorry state of the Hudson – a dead river back then – and pass his banjo through the crowd for people to stuff in a buck or two toward his dream of building a replica of the great Dutch sloops of the past, to be used to educate and agitate. This improbable grassroots effort actually worked; the Clearwater was launched in 1969. The sloop picnics continued and grew in popularity as the new ship gained visibility, and by 1978 the Revival had become a full-scale festival housed at Croton Point Park, with big-name musical talent organized in the early years by Towne Crier impresario Phil Ciganer.

That first decade at Croton Point was a wonder. The huge park allowed for four major stages, sufficiently far apart that the sound from one didn’t drown out the others, and easily accommodated 15,000 to 20,000 festival attendees per day. Yet even on such a large scale, the Revival remained safe and kid-friendly and down-to-Earth, promoting a shared vibe of fun, music and appreciation for the Hudson River’s natural wonders. You could even catch a short ride on the sloop herself if you didn’t mind waiting in line for a bit. But the view of Indian Point’s cooling towers was always there to remind us of Clearwater’s serious mission and the need for a collective environmental consciousness in the Valley.

Then, in the late ‘80s, the festival hit a bit of a slump. Croton Point had a leaking landfill that needed cleaning up, so the Revival had to spend ten years in exile far from the Hudson’s shores – on the campus of Westchester Community College, whose layout was really not conducive to a festival on such a large scale. Happily, by 1998 the reclamation work at Croton Point was complete, and the Revival was able to return to its natural home. You can ever get there by Metro North; the site is within walking distance from the train station for the able-bodied. For those not so mobile, the festival has always bent over backwards to accommodate people with disabilities, roping off roomy sections in front of each stage for wheelchairs and putting lively American Sign Language interpreters in the wings to perform every song alongside the stage acts. They’re fun to watch, even if you can hear perfectly well!

As for those acts, it’s hard to know where to begin (or leave off) listing this year’s performers. Besides the ubiquitous Pete, they include the infrequent visitor to these shores Billy Bragg, David Bromberg, Buskin and Batteau, Guy Davis, K. J. Denhert, Justin Townes Earle, the Felice Brothers, Arlo Guthrie, Janis Ian, the Indigo Girls, Jorma Kaukonen, the Klezmatics, the Nields, Red Horse (better-known individually as John Gorka, Eliza Gilkyson and Lucy Kaplansky), John Sebastian, Martin Sexton, Chris Smither, Suzanne Vega, Dar Williams, Peter Yarrow and many more. As always, there will also be smaller stages, tents and dancefloors dedicated to kids’ music, storytelling, puppet shows, songwriting workshops, participatory jam sessions and group lessons in square, contra, swing, clog, Cajun and other dancing styles – not to mention the odd buskers of various sorts wandering the grounds.

This year, both the Saturday and Sunday evening performances will end with what are being called the “Clearwater Generations Sets,” featuring Pete and his grandson Tao Seeger, Arlo and his daughter Sarah Lee Guthrie, Peter and his daughter Bethany Yarrow, Bernice Johnson and her daughter Toshi Reagon, John and his son Ben Sebastian, Tom and his niece Jen Chapin (Harry’s daughter), Jay Ungar and his daughter Ruthy Ungar Merenda and David Amram and his kids. Didn’t we tell you that it was a family-friendly event?

The music begins at 11 a.m. on Saturday, June 18 and officially ends at 8:30 p.m. on Sunday, June 19 although it’s not unusual for the final set of each night to run over. I’ll never forget one Revival in the ‘80s that ended on the Summer Solstice with the Paul Winter Consort playing an extended jam of “Wolf Eyes” and a crowd of thousands howling along at the Full Moon until very late indeed.

Tickets are available at discounted advance prices via the Clearwater website through this Friday, June 17. Entry for Saturday or Sunday only costs $70 in advance, $85 at the gate general admission; $60 in advance, $80 at the gate for Clearwater members. A full weekend pass goes for $95 in advance, $140 at the gate for non-members, $80 in advance, $125 at the gate for members. Add camping on-site and you pay $150 for the whole weekend in advance or at the gate for non-members; members get the camping pass for $140 if bought in advance only. Seniors age 62 and over get a 15 percent discount on all ticket rates, and kids age 12 and under get in free with an adult. Oh, and for a mere $1,000 donation, you get a full weekend pass plus admission to an intimate concert with Jackson Browne, waterfront reception and evening sail on Friday, June 17. To pre-order tickets or view the full 2011 Great Hudson River Revival schedule, visit www.clearwater.org/festival.