Finance Minister Bill Morneau is facing increased pressure from aboriginal advocates to move beyond symbolism in his maiden budget and spell out how the federal government intends to reform its fiscal relationship with First Nations — an overhaul that could cost billions.

In a letter to Indigenous Affairs Minister Carolyn Bennett, New Democrat MP Charlie Angus said he is deeply concerned about a giant funding hole for First Nations education revealed by the government last week.

The Liberals were banking on $1.7-billion in funding from the previous government to form the basis for their election pledge to invest $2.6-billion in core First Nations education over the next four years.

It turns out the money, tethered to quashed Conservative legislation, is no longer available, prompting a pre-budget scramble.

In a statement earlier this week, a spokesman for Morneau said the government's commitment to indigenous communities, including First Nations kids, remains strong.

Concern in Saskatchewan

In Saskatchewan, concerns about the Liberals meeting their campaign promises were also flagged.

"We've been informed the government may not make the education investment they promised before the election," Bobby Cameron, chief of the Federation of Saskatchewan Indian Nations (FSIN), said in a statement Thursday. "It is absolutely imperative and crucial that this funding increase and commitment happens."

Cameron's statement did not disclose how the FSIN came to know about the government's intentions.

According to the statement, a student in an on-reserve school requires $20,000 per year for a quality education. However, the average funding provided, from the federal government, is $6,500 per student.

Cameron added that the federal budget should be viewed as "an opportunity to begin the spirit of reconciliation and building a nation-to-nation relationship."

Costing promises

The NDP's Angus said he's concerned the education funding controversy — which the NDP warned the Liberals about during last fall's election campaign — is only the tip of the iceberg when it comes to the government's costing of promises to indigenous peoples.

"Your party's failure to properly cost its promises must not be placed on the backs of indigenous peoples — that is the oldest story of Confederation," the NDP's indigenous affairs critic said in the letter to Bennett.

Angus noted recent numbers provided to his office outline the magnitude of another critical issue: dozens of First Nations communities have been under boil water advisories for a combined total of more than 327,000 days.

He said the figures show 136 drinking water advisories were in place in 92 communities in November — not including B.C. and the territories.

Aboriginal Trudeau

Prime Minister Justin Trudeau and AFN National Chief Perry Bellegarde laugh as they talk before the beginning of the Assembly of First Nations Special Chiefs Assembly in Gatineau, Dec. 8, 2015. Trudeau's government is under pressure to back up his promise of a new relationship with indigenous peoples with tangible funding commitments. (Adrian Wyld/Canadian Press)

Prime Minister Justin Trudeau has vowed to end these advisories within five years but there must there must be funding and a plan attached to it, Angus added.

"How will this government fulfil the prime minister's promise, which appears to not have been costed or included in your government's platform, focuses on boil water advisories instead of safe drinking water and appears to exclude entire regions of the country?"

Solutions could come with a hefty price tag, based on a 2011 government study.

It indicated water and wastewater servicing needs could cost $4.7-billion, plus a projected operating and maintenance cost of $419-million per year, Angus noted.

New funding relationship

The Liberals have also made other sweeping commitments on the aboriginal affairs file including a promise to lift the two-per-cent cap on annual funding increases for reserve programs and services.

During pre-budget submissions to the Commons finance committee, Dale LeClair of the Assembly of First Nations estimated that about $25.5-billion in federal money has failed to flow to communities since funding was capped in 1996.

In an interview last month with The Canadian Press, Truth and Reconciliation Commission chairman Murray Sinclair warned Canada must find a new way of doing business with Aboriginal Peoples if it wants to save money down the road.

"If they dealt with that trauma and pain in a proper way, coming out of that experience, the amount of money that they are spending on those areas would probably be reduced in the long term," Sinclair said.

The TRC, sparked by the largest class-action settlement in Canadian history, delivered 94 calls to action which touched on a host of issues including health and education.

$200M funding gap

Trudeau has promised to implement all the recommendations but the government has not provided a road map on how much that will cost, noted Don Drummond of Queen's University, a former senior official with the federal finance department.

It will take an additional $200-million a year just to close the funding gap on child welfare, according to the First Nations Child and Family Caring Society of Canada.

The society's president, Cindy Blackstock, and the AFN spent nine years fighting the federal government, arguing it failed to provide First Nations children the same level of welfare services that exist elsewhere, contrary to the Canadian Human Rights Act.

In January, the Canadian Human Rights Tribunal ruled in their favour and the government has opted not to appeal this decision.

With files from Andy Blatchford and CBC News