Is the Conservative government in Ottawa out to destroy Downsview Park? That is what local City Councillor Maria Augimeri is claiming.

At a public meeting on Wednesday, she took aim at Canada Lands, the federal agency in charge of Downsview. "You are selling our parkland," she thundered. "You are selling the heritage for our children and our children's children."

Away from podium, she told me: "These people would sell their grandmother if they could. These people are dollar hungry. That's all they see out of their eyes: dollar signs."

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What could possibly justify such language? Ms. Augimeri might be forgiven if the threat she is warning about were real. It isn't. Canada Lands executive Robert Howald assured the meeting that it has no intention of selling parkland or even of increasing densities in the parts of the sprawling Downsview lands that are designated for residential development.

Ms. Augimeri calls those assurances "lies." Her supporters yelled "B.S." and chanted "park, park, park." Even Olivia Chow, attending as a candidate for mayor, told the crowd she is skeptical about the city-approved "secondary plan" for the lands. "My worry is that this secondary plan does not work," she said. "It is now a housing development rather than a park."

In fact, Downsview is meant to be much more than a simple tract of grass and park benches. In 1994, the government of Liberal prime minister Jean Chrétien announced a plan to create a national urban park at Downsview, long home to a military base and aircraft factories. The park was to be self-financing. In practice, that meant leasing or selling some of the land for development, with the remainder to remain public space. Blueprints envision a mix of public parkland, sports facilities, cultural uses, housing and commercial space. The secondary plan was approved by a vote of city council and upheld by the Ontario Municipal Board.

After a slow start, the plan has begun to take shape. Downsview has become a sports hub, hosting modern facilities for squash, soccer and other pursuits. It includes film studios and outdoor-concert grounds. The park opened in 2012 and boasts 70,000 new trees.

In the coming years, five new neighbourhoods are to rise on adjoining Downsview lands, each with extensive parklands of their own. Plans also call for a "cultural commons" with a public square and indoor community space. The planners take their inspiration from the Wychwood Barns, old streetcar sheds repurposed for community space, and the Evergreen Brick Works, an environmental centre in the Don Valley.

None of this impresses Ms. Augimeri. She suspects that the park "will be whittled away to nothingness. There will be very little useable park space."

Her fears rest on the fact that Ottawa put Canada Lands in charge of the 232-hectare site. The fears gained fuel when the Toronto Star obtained a 2012 memo from a senior federal official saying that, as a real-estate company, Canada Lands "may be inclined" to dispose of some of the land. Both the government and Canada Lands insist they won't do anything of the sort, and they would face an almighty storm if they did.

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If, on the other hand, Canada Lands simply proceeds with the creative plan for the site, the city can only benefit. With a new subway stop going in and nearby highway access, Downsview is an ideal place to build a truly urban space, mixing traditional parkland – lawns, woods, bike paths, walking trails, sports fields – with athletic facilities and community spaces that attract people year-round. Adding attractive new neighbourhoods and new roads to link them will only bring more life to what might otherwise have become a vast, blank and underused space.

"We live in the biggest city in the country," says Anthony Fernando, who is running against Ms. Augimeri in the October election in her district, Ward 9. "An 'urban park' is going to be … urban. The pluses far outweigh the minuses here."

That is a far more sensible take on Downsview than Ms. Augimeri's conspiracy theory.