New Yorkers love a perfect summer night under the stars, with a great live band, a steady flow of beer, and several thousand of their neighbors hanging out in a state of suspended urban bliss. That was the scene at McCarren Park Pool a couple of weeks ago when the Chicago rock group Wilco headlined the venue, a 6,000-person-capacity site in Greenpoint, Brooklyn, that has become a staple of the city’s warm-weather concert season.

Wilco’s generous 2 1/2-hour set unfolded before a concrete and brick expanse that hadn’t served bathers since the city shackled the facility in 1984 before reopening it as a venue for large-scale music events — among other diversions, including dodgeball competitions — in 2006. It was easy to see the appeal: endless room to roam, extremely wide sight lines, a sloping surface that provided good angles to the stage, lots of fresh air, and the strangely picturesque glow of new, high-rise condominiums surrounding the block.

Alas, it all comes to an end Saturday, when New York rock icon Sonic Youth headlines the final concert at McCarren. Three summers of dance performances, theater productions, movie screenings, and rock concerts will conclude as the City Department of Parks and Recreation shuts down the pool to begin a $50 million renovation project. If all goes as planned, the now-empty basin will reopen in 2011 as a glimmering oasis: an actual swimming pool, albeit downsized to accommodate between 1,400 and 1,700 bathers.

“We’re definitely sad to be losing the place,” a party promoter with JellyNYC, Dan McGinley, said. “It’s a huge space, a very unique space, with a lot of history. A lot of people had a lot of good times there before we started putting on shows.”

In each of the last three summers, Mr. McGinley and his cohorts at JellyNYC produced nine free “pool parties.” The Sunday afternoon events, featuring such indie favorites as Blonde Redhead, Aesop Rock, and Yo La Tengo, offered a populist alternative to the many ticketed events at McCarren, which also hosted acts such as M.I.A., the Hold Steady, and the Black Keys. Conveniently located at the dividing line between Greenpoint and Williamsburg, the pool sits at the epicenter of Brooklyn’s under-30 hipster demimonde. It would be hard to imagine anything more appealing to a hungover clubgoer than a ride on an improvised Slip ‘n Slide in a park populated by a score of semi-nude, tattoo-laden, and extremely pale peers, supplemented with live music courtesy of TV on the Radio or the Yeah Yeah Yeahs.

Scan the Internet and you can hear their anguished cries. “Save the pool parties, Obama!” one such individual wrote, anonymously, on the music-oriented Web log BrooklynVegan.com.

Built by Robert Moses in 1936 as a project of the Works Progress Administration, the 50,000 -square-foot site has long been the target of activists seeking to restore the pool to its former aquatic glory.

“The community, for more than 20 years, has called for the pool to have water in it again,” the city’s administrator for parks in north Brooklyn, Stephanie Thayer, said. Ms. Thayer is also the executive director of the Open Space Alliance for North Brooklyn, a nonprofit organization that has made McCarren its pet project. The group raised $500,000 to construct a stage for the pool’s concerts this summer after Live Nation, the country’s top concert promoter, withdrew its support after providing a stage and other amenities. Live Nation kicked in an initial $200,000 in 2006, after the choreographer Noemi LaFrance asked the city for permission to stage a dance installation at the pool, which was in extreme disrepair. One thing led to another, and the venue quickly became a hot spot, even as decades of community pressure finally began to have an effect.

“Concerts were always an interim use until money came along to put water in the pool,” Ms. Thayer explained.

Once reopened, the pool is intended to be available for off-season events during the spring and fall, as well as ice-skating in the winter, with newly expanded facilities for a community center. As Ms. Thayer noted, Greenpoint and Williamsburg are underserved in terms of public park spaces, something that has become a growing concern as the population of the neighborhoods has boomed along with waterfront real estate development.

Meanwhile, Mr. McGinley insisted that the shows will go on again next summer — somewhere. Perhaps it will be in Bushwick Inlet Park, a 28-acre green space on the waterfront at 12th Street and Kent Avenue, whose redevelopment has been the focus of much community interest.

Added Ms. Thayer, “We’re actively looking at every possible option.”