New Yorkers hungry for some theme park action may soon no longer have to head out of the city.

A lease for a Great Adventure-style water park on Randall’s Island that will include water slides, wave pools, and an indoor beach is coming up for final approval in a few weeks.

The city’s Franchise Concession and Review Committee approved the proposal for the 26-acre park in January and will vote in April on the final contract the city hashed out with Aquatic Development Group, the company chosen to build the theme park.

“There are a lot of residents who leave the city to go to water parks,” the city parks commissioner, Adrian Benepe, said yesterday. “Keeping those dollars here is going to be a good deal for the city.”

Under the contract the city will present to the FCRC, it would get $1 million in annual rent in addition to a percentage of the company’s revenues. The company also would be required to pay $21.7 million in “payments in lieu of taxes” during the first 10 years of business, to put down a security deposit, and to give the city 25% of any future advertising revenue, the director of revenue and concessions for the Parks Department, Ron Lieberman, said.

If approved, the 26-acre site – which is located on the northern nook of the island, adjacent to East Harlem and the South Bronx – would be home to the first such water park in any major city.

“These parks are all in the suburban and rural areas,” the chairman of the Randall’s Island Sports Foundation, Richard Davis, said.

When asked whether such a park was too suburban for New York, Mr. Benepe said: “Not everybody wants to go to an evening lecture on Alexander Pope.”

Not everyone is backing the project. The city’s comptroller, William Thompson Jr., has taken issue with the ballooning costs and size of the project. The $168 million project was first proposed under Mayor Giuliani in 1999 at 12 acres and $45 million.

Mr. Thompson, who has a vote on the FCRC, called the selection process “flawed and inconsistent with well-established principles of public bidding.”

The president of Manhattan, Scott Stringer, was recently quoted saying he is worried about whether residents of East Harlem and South Bronx will be able to afford admission.

Mr. Benepe said the facility would include a free “swim academy” for 2,000 children in nearby neighborhoods.

A former parks commissioner, Henry Stern, said the city needs to ensure that it’s financially protected.

“What happens if they go broke or if they abandon it?” he said of Aquatic. “Will the city be stuck with a white elephant?”

While city officials would not share the proposed contract, they said protections are in place. They also called Aquatic a solid company, despite a 1995 Chapter 11 filing.

The Bloomberg administration estimates that the project, to include outdoor and indoor water parks, will bring in 1.5 million visitors a year and employ hundreds. It also notes that Aquatic will pay for construction of the project and that the city can bring in another operator if the company backs out.

Approval of the contract would be the final public hurdle for the project and would add another venue to the island’s growing list of other sports and entertainment venues.

The proposed contract includes a revenue-sharing scale that gives the city different amounts of money at different thresholds and at various points in the 35-year lease.

For example, in the first five years of operation the city would get 6% of all revenues if the park makes $70 million or less, 8% if it makes between $70 million and $80 million, 10% if it rakes in between $80 million and $90 million, and 12% of anything more than $90 million. The city would get slightly more after the fifth year.

While most “payments in lieu of taxes” are considered tax breaks, Mr. Lieberman called the contract’s $21.7 million in “pilot” payments “bonus” money because companies that operate on parkland do not pay real estate taxes.

The FCRC hearing is scheduled for April 10, with a vote the next day. If the lease is approved, the park could open in 2008.