Internal documents from the Department of Indigenous and Northern Affairs obtained by CBC show that when funding for a much-needed road to the isolated Shoal Lake 40 First Nation was announced last December, government officials knew the costs would be much higher than the $30 million estimate cited publicly.

A concept-phase early estimate for the Shoal Lake 40 Freedom Road dated Dec.1, 2015, obtained through a federal access to information request pegged the full cost at $52.47 million. The estimate has since been revised down to $46.5 million.

But that is still $16.5 million higher than the original estimate of $30 million. That number was cited in December when the mayor of Winnipeg, the premier of Manitoba and federal minister of indigenous affairs announced a three-way funding split for the building of the road.

There is no agreement yet on how the extra costs will be covered, but Prime Minister Justin Trudeau says he's still committed to getting the road built.

"I was in Shoal Lake a few weeks ago, and I expressed my commitment to the people of Shoal Lake that we were going to get the road built," Trudeau said Friday.

Lack of clean drinking water

For over a century, Winnipeg, 135 km to the west, has drawn its water from Shoal Lake, which straddles the Manitoba-Ontario border.

In 1914, land was expropriated from the Shoal Lake 40 First Nation to build an intake, and construction left the community on a man-made island, with no road access, despite being only about 30 km from the TransCanada Highway.

Prime Minister Justin Trudeau, left, met with Winnipeg Mayor Brian Bowman, right in Winnipeg on June 3 to work out how they would split the extra costs of the Shoal Lake 40 Freedom Road project. Manitoba Premier Brian Pallister also attended the meeting. (Cameron MacIntosh/CBC)

That isolation has also left the community without clean drinking water of its own, as a lack of road access has made a water treatment plant unfeasible.

In recent years, that bitter irony has generated considerable public and political support for the First Nation as it appealed to the city, province and federal government for all-weather road access.

Aboriginal community has gone years with no clean drinking water because a treatment plant was too expensive 2:27

The $30 million figure was based on a 2010 feasibility study. The new estimate, prepared by AECOM Engineering, which is doing the project design work, includes increased costs for rock excavation, improvements to the intersection where Freedom Road will meet the TransCanada Highway, including acceleration and deceleration lanes, as well as deviations from the originally proposed route.

The aqueduct from Shoal Lake delivers 225 million litres of water to Winnipeg every day and cost $17 million to build. That would be $276 million in 2019. (CBC)

The provincial agency overseeing design and construction says the costs of the project are still fluid, as final design work is still being completed.

"When they get into the design, the geotechnical and look at the challenges they start to face, that's when it changes," said Daryl Harvey, vice-president of Manitoba's East Side Road Authority.

"Our engineers are working with the community and designers to get to what the actual number is going to be."

Road will need to be longer

Originally, it was hoped the cost for Freedom Road would be kept down by following a route already cleared for a temporary service road that leads to a railway.

Internal emails from the Department of Indigenous and Northern Affairs obtained under the same access to information request say only about 600 metres of that existing route meet geometric standards for a provincial road. Freedom Road will also need to be 2.8 km longer than the 24 km originally planned.

People in Shoal Lake on the Manitoba-Ontario border have been under one of the longest boil-water advisories in Canada – nearly two decades. (CBC)

When complete, Freedom Road will be a gravel, two lane, low speed, low load, provincial road with an 80 km/h speed limit.

Those same emails say the province, which is taking the lead on construction, expressed "sticker shock" over the new estimate.

As the announcement for $30 million was made in Winnipeg, government officials and Shoal Lake leadership were discussing escalating costs behind closed doors.

TIMELINE | A history of Shoal Lake 40 First Nation

"Internal discussion acknowledged this would go higher," said Shoal Lake 40 spokesman Cuyler Cotton.

Shoal Lake 40 First Nation is finally getting road access to the community after three levels of government announced $30 million in funding Thursday. 1:40

Talking points for the indigenous affairs minister, obtained by CBC, acknowledged costs could go higher and said any increases "would need to be approved by all the partners in the project."

Trudeau met with mayor, premier

In a statement, Manitoba's new Conservative provincial government said it wouldn't commit to additional funding but said it recognized "the importance of the Shoal Lake road as a lifeline for that community."

Trudeau met Friday with Manitoba's new premier, Brian Pallister, and Winnipeg's mayor, Brian Bowman.

Bowman says it's not yet clear how the extra costs will be split.

"As the estimates come in and as they revisit it, we will work collaboratively with the other levels of government to get the job done," the mayor said.

Trudeau says he's optimistic a deal will be worked out

"We'll work out in flexible ways how it is that we make sure that everyone pays their share," he said.

It was hoped construction would start in late 2016, but it's unclear whether that timetable can still be met.

And costs could be higher still.

The final design study and cost estimate, originally expected this spring, has been pushed back to July 1.

Before construction, the design will also have to pass a provincial environmental assessment.