HOBOKEN -- Outgoing Mayor Dawn Zimmer opened a temporary "pop-up" park on Monday on the former 6.1-acre BASF site, ahead of a permanent Northwest Park there that could take several years to complete.

Under a scorching afternoon sun, teenagers played basketball on full-courts, toddlers giggled with their parents under sprinklers, and kids swung on swings.

"This is really something that's going to change this neighborhood and change the city," Zimmer said at the park at Adams and 12th streets. "This is just a pop-up park. We wanted everyone to enjoy the park right now, but once this is built out this will be our largest park in Hoboken, a 5-acre park. And I'm extremely, extremely proud of all we've gotten done."

Along with flood protection, creation of additional park space space has been a priority for Zimmer during her two four-year terms as mayor. Northwest Park involves both issues.

The Northwest Park project will also include an underground detection system that will be able to absorb a million gallons of water that would otherwise flood the streets and basements of Hoboken's low-lying western region.

Zimmer recently announced she would not seek a third term in November. During the Monday afternoon park opening, she was joined by three of the four local elected officials vying to take her place as mayor, including two members of the City Council, which voted unanimously last fall to purchase the BASF site for $30 million.

Council President Jennifer Giattino and Councilman-at-Large Ravi Bhalla, were joined Monday by Hudson County Freeholder Anthony Romano, who is also running for mayor. First Ward Councilman Michael DeFusco, a mayoral candidate who also voted for the park purchase, did not attend Monday's event.

Officials have estimated the total cost of the park at around $50 million, including the acquisition price and the cost of the detention system, design and engineering work, and construction. A municipal parking garage is also planned for about a half acre of the BASF site, which will be adjacent to the 5.4-acre park.

Juan Melli, a Zimmer spokesman, said there was still no estimated opening date for the completed park, but that design and engineering work would take about two years. Giattino said the council was scheduled to award a contract for the job at its meeting on Wednesday.

Dave Quevedo, a 36-year-old local resident and businessman, and his 18-month-old daughter, Emerson, who was splashing in water from a nearby sprinkler. Quevedo said the pop-up park was better than none at all, but he was eager for the permanent version.

"More trees, more shade," were what Quevedo wanted to see. "Grass would be fantastic."

Told of the impromptu constituent complaint, Melli pointed to a grove of saplings that stood atop the asphalt in large wooden planters. But, he conceded, "There's no pop-up grass."

Steve Strunsky may be reached at sstrunsky@njadvancemedia.com. Follow him on Twitter @SteveStrunsky. Find NJ.com on Facebook.