The redevelopment of Parramatta stadium will require demolition of the adjacent community pool, which closed at the end of March.

The government has announced it would contribute $30 million towards a new aquatic centre on a section of Parramatta Park known as the Mays Hill precinct, three-quarters of which was until recently used as a golf course.

The Parramatta Park Trust has unveiled a proposal to transform the land into "an active urban parkland with better connectivity to the core park in the north."

"Protection of heritage views and community recreation opportunities are key considerations in the planning process," it says.

A bill due to be debated in the NSW upper house on Tuesday hands Parramatta Park Trust the power to lease the land for facilities associated with the new aquatic centre.

But the scope of the potential development has alarmed the state Opposition.

The bill states that the trust may lease land for the new leisure centre or "any purpose associated" with the centre for up to 50 years.

This includes "gymnasiums, sports courts, public amenities, cafes, spectator seating, barbecue areas, health and well-being facilities, ancillary administrative areas, associated care parking facilities and the outdoor recreation and leisure spaces".

Currently, development is restricted to purposes associated with "the operation and maintenance" of the now-closed pool.

Labor's sports spokeswoman Lynda Voltz accused the government of "using its stadiums policy as cover to commercialise up to a quarter of Australia's oldest public park".

"Hawking off public parkland for a gym and a 'wellness' centre is nothing short of disgraceful," she said.

"This is space that should be protected for future generations not sold to the highest bidder."

Ms Voltz said Labor would seek to amend the bill to allow 1400 square metres for a new Parramatta pool in the Mays Hill precinct but put "safeguards around the rest".

Mays Hill Precinct. Photo: City of Parramatta

But spokesman for environment minister Gabrielle Upton said: "The NSW government wants the City of Parramatta Council to design the best possible aquatic centre for the people of Western Sydney because they deserve a world-class one.

"The design of the aquatic centre will be subject to all the regular planning and heritage approvals and maximise green space," he said.

"The aquatic centre will only occupy a portion of the Mays Hill site."