Ottawa may have to find a route other than the Ottawa River Parkway for its light rail project after the National Capital Commission rejected a line along the waterfront thoroughfare.

The city had been studying the parkway as a possible path for the western section of its planned new light rail transit line.

But the NCC, which maintains the parkway, said the city's most recent presentation failed to make a compelling case for using the prime tract of public land for a transit line.

"We own the land on behalf of Canadians, so when you're looking at letting the parkway be used, it's gotta be a really compelling case that it is for the greater good of the capital region. So does it provide opportunity to create densification, can it create access to water, to commercial?" NCC chief executive Marie  Lemay said in a CBC interview Thursday.

Two other options for the LRT line are along Carling Avenue, or via Richmond Road and Byron Avenue.

"Looking at the three corridors, it became very obvious that the components that were important to us were better met with other options," Lemay said. "When you look at the other corridors, there's a lot more opportunities to densify and to create densification and urbanization around those stations and the line."

Lemay said the city's presentation made it clear municipal officials were keen on the Ottawa River Parkway route because it would be the fastest option to bring commuters into downtown, whereas the NCC is more concerned about urbanization.

The city is asking the commission to wait until an environmental assessment of the western corridor is complete before making up its mind.