Barry Diller defended the use of private funding for New York parks, saying it’s the only way to build ambitious projects such as his new Pier 55 project on the Hudson River.

Last year Diller and his wife, Diane von Furstenberg, announced a $113 million grant for Hudson River Park’s Pier 55 – a project much grander than the average city park.

“When you cross that bridge and you enter it I really want it to feel like the scene from the Wizard of Oz when it turns from black and white to color,” said Diller during a panel discussion at the Municipal Art Society’s annual summit.

Pier 55 is part of an ongoing effort to complete Hudson River Park, which was originally expected to be done by 2003 at a cost of $300 million. The Hudson River Park Trust’s CEO, Madelyn Wils, said it could end up costing over $1 billion to complete the full stretch between Chambers Street and West 59th Street.

“Eventually all the jewels in the necklace will be completed,” she said.

Pier 55 will feature a 750-seat amphitheater, thousands of plants and state-of-the-art green spaces. The project is expected to cost $130 million, of which the city has agreed to contribute $17 million. Once complete, the 2.7-acre space will host concerts and theatrical performances and be open to the public for recreation.

Advocates say the city’s other 29,000 acres of parkland could benefit from this type of investment. The Department of Parks and Recreation’s $454 million FY16 budget is $20 million lower than the previous year, though still higher than it has been in recent years.

Yet the agency has struggled with maintenance and efficiency issues. According to a report earlier this year by Comptroller Scott Stringer, Parks ranked last out of all agencies for percentage of capital commitments achieved in FY14.

The president of New York City Park Advocates, Geoffrey Croft, said the rise of park conservancies has given private donors too much influence. He cited a philanthropist’s 2012 attempt to build a $40 million bike velodrome in Brooklyn Bridge Park as an example of not using funds in a way that will benefit the general public.

“People forget that the land doesn’t belong to them,” he said via phone. “They’re allowed to live in this alternate universe and that’s what’s really disturbing.”

Croft has criticized the lack of public input on Pier 55 and the sense of inevitability behind the project. A lawsuit has been filed by a civic organization, the City Club of New York, to halt construction until a more thorough environmental review is completed. Approval of permits from the state legislature and the Army Corps of Engineers are still pending.

None of these hurdles were mentioned during the panel discussion. Diller said public-private collaborations are the way of the future – citing Central Park and the High Line as examples – and said people should be happy about philanthropic efforts.

“I don’t know what part of it is bad,” he said.