Expanding parks is not supposed to be this difficult.

“This is the worst situation I’ve ever encountered in terms of [dealings with] the community,” said Carol Greitzer, a former councilwoman from the West Village who helped start a group called 250+ Friends of New York Parks. It opposes many of the Bloomberg administration’s park plans. “They come up with a plan. Maybe—maybe—if you’re lucky, you can tweak it slightly, but that’s about all you can do.”

The examples of such contention over fresh parkland are myriad as of late, raising questions of government priority and private sector meddling over a basic concept that ordinarily isn’t so controversial—who, after all, is against more parks?

In Union Square Park, opponents have so far succeeded in halting construction, with a lawsuit, of a possible seasonal restaurant. The concept of a park-based restaurant in an area lined by them has frustrated some in the community, as the idea is being pushed by the area’s business-improvement district.

Lawsuits or political opposition have also hobbled plans for new ball fields on Randall’s Island; a redo of Washington Square Park; and the future of a key pier in Hudson River Park, with opponents of the projects complaining that the city’s decisions lack meaningful public input.

Much of the contention springs from public-private partnerships undertaken by the Bloomberg administration to develop or to change the parks. The administration has countered that such partnerships often spur the very changes that would otherwise never occur.

Still, the distrust and the anger mounts.

“There’s more trouble now with the community groups in this last four years than there was before,” said Henry Stern, the former city parks commissioner under Mayors Ed Koch and Rudy Giuliani. “There is a pattern of resistance.”

THE INCREASED RESISTENCE stems in part from the sheer number of projects the city has undertaken, particularly with the environmental PlaNYC initiative announced last year.

The Parks and Recreation Department, led by Commissioner Adrian Benepe, is working on dozens of creations and expansions around the city, spanning from a new, 2,200-acre Fresh Kills Park in Staten Island to creating a parkland-lined shore along the Williamsburg and Greenpoint waterfronts.

Staffing and funding levels have accordingly risen for the department in the Bloomberg administration, with about $1.21 billion being devoted to capital investments in the mayor’s first five budgets. That number is compared with $1.07 billion for the prior five years, and $665 million for the five years before that, according to inflation-adjusted figures from a Citizens Budget Commission Report and the city comptroller’s office.

With respect to community opposition, the Parks Department emphasizes its full plate of projects, saying that a wide array of initiatives is bound to attract controversy.

“No great urban development project comes without temporary inconveniences to the community and even controversy,” Mr. Benepe said in an e-mailed statement. “Parks are our common backyards, and most New Yorkers have strong proprietary feelings for their parks and are not shy about expressing their opinions.”

The agency also noted that it consults the community boards about park alterations, and has an active community engagement program.

But critics claim the frequent dissonance with the city stems more from the decision-making process at the Parks Department, saying the agency fails to take in community input and is inflexible in its positions.

Assemblywoman Deborah Glick, who has criticized many recent park initiatives, said the city has an “inherent arrogance that has been more in evidence over the last few years.

“Scarcity creates conflict; scarce parkland is a hot commodity,” she said.

IN MULTIPLE PARKS projects, the tactics of opponents have been similar, relying on a lawsuit to delay or to stop the project. Taken with the support of a local elected official, such opposition can either block the initiative or result in changes to the plan to help mitigate concerns.

Construction of the pavilion at Union Square is now delayed indefinitely as a judge considers a lawsuit, which claims the city needs state approval to make way for a new restaurant.

In the fight over the redesign of Washington Square Park, a plan that many community residents vehemently opposed over numerous design issues, opponents held up the project for months with multiple lawsuits. The project, to which the Tisch family pledged $2.5 million to help move and redo the park’s central fountain, is now moving forward after the city made some changes that community members requested.

And at Randall’s Island—perhaps the most clear-cut example of private sector involvement—park advocates won a legal battle in January in which they alleged the city needed to gain approval from the City Council for an expansion plan. The city had agreed to expand the amount of ball fields on Randall’s Island from 36 to 63, taking $52 million from private schools to do so. In exchange, the city would have agreed to set aside two-thirds of the fields for the private schools three hours every weekday.

There was no lawsuit over the fate of Pier 40 in Hudson River Park; however, West Village residents have successfully fought off a proposal by the Related Companies for an entertainment complex, in large part because Assemblywoman Glick vowed to block it in the State Legislature. The West Side park, controlled jointly by the city and the state, is supposed to gain crucial operating revenue from some sort of commercial operation at Pier 40.

Opponents of the Related plan fought it because they said its scope was out of character with the neighborhood. But if another viable alternative is not found, at some point the park will need additional operating funds to come from some other source.

Whatever the tactics, opponents of individual projects have delayed or halted them at a time when construction costs are rising and the clock on the Bloomberg administration’s tenure is ticking down, frustrating those in the city.

How could the opponents be appeased?

More consultation and more public money for parks, they say, as it would free the city from a reliance on private funding.

“Parks are not a priority,” said Geoffrey Croft, president of NYC Parks Advocates, which was a plaintiff in the lawsuit at Union Square Park. “The government doesn’t want to be in the business anymore of building and maintaining parks.”

The Bloomberg administration vigorously contests such a viewpoint, and Mr. Benepe frequently hails the city’s investment in parks as a new golden age for the system. He has also stood strongly by the department’s private partnerships, which amount to about $87 million that private groups contribute annually to the system, along with the $48 million the city takes in from concessions each year, according to the Citizen Budget Commission report, though the concession money goes to the city’s general operating fund.

The amount of funds derived from the private sector are poised to rise in coming years.

A Regional Plan Association study last year estimated that the approximately 700 acres of new waterfront parkland would cost an average of $135,000 an acre to maintain annually, which, at around $100 million a year, seems like it will be difficult to fund.

“You have this explosion in new park space, which is great, and something we’ve all fought for, and it’s going to help close the gap when you think about the park needs of the city going forward,” said Rob Pirani, an author of the report. “But it’s going to cost money to maintain it.”