Winnipeg's mayor declined to speculate why the federal government is not funding upgrades to the North End Water Pollution Control Centre, a $1-billion project that ranks as the most expensive on the city's books.

The price tag for expanding the capacity of the North End sewage-treatment plant and improving the environmental quality of its effluent rose at least $205 million last week, when water and waste officials disclosed the results of a more detailed project estimate.

To date, the provincial government has pledged $195 million for the project, which is the result of a 2003 provincial order to clean up Winnipeg's sewage-treatment effluent and reduce the nutrient loads in the Lake Winnipeg watershed.

Ottawa has not contributed any funding to the project, water and waste officials said in a report.

"That's a question for the federal government. What I can say is, if they have a billion dollars, we'll take it. We're going to continue to work with both levels of government, both federal and provincial, to try to access funds as best we can," Bowman said Monday in a scrum outside his office at city hall.

The mayor could not say whether he's ever asked the Trudeau government to help the city build the sewage-treatment upgrades.

"We've had ongoing dialogue with many members of the federal government. Typically, we channel the formal requests through the public service and administratively," Bowman said.

"I've had discussions with many members of the government, including the prime minister, in terms of financial support for the City of Winnipeg, but to go back and say specifically for this project? It's been done mostly administratively."​

Winnipeg usually pays for sewage-treatment projects by increasing water-and-sewer charges and borrowing.

In 2003, when the province ordered upgrades to all three of the city's sewage-treatment plants, it was expected the other two levels of government would cover at least two-thirds of the cost.

Council water and waste chair Brian Mayes (St. Vital) said the North End upgrade is Winnipeg's greatest funding need.

"This is the biggest capital project we've ever done and so I do think there's a federal role for this," Mayes said Monday, following a water and waste committee meeting.

"In the end, 'sewage isn't sexy' is probably as good a summary of this as can be. It's a billion dollars."

The latest hike in cost estimates for the North End plant are due to Canadian dollar projections and more detailed plans, water and waste engineering manager Geoff Patton said Monday.

The city expects to look for a partner to design and build the upgrades in 2019, but the project won't wrap up until the middle of the next decade, he said.