A controversial 6.6 billion Canadian dollar (5.9 billion US dollar) energy project will go ahead in northern British Columbia, provincial officials announced Monday.

The Site C dam has yet to pass independent environmental assessments, but if construction is on schedule the 900 megawatt dam on the Peace River would start powering some 410,000 homes in 2020.

The dam would flood about 83 square kilometers (32 square miles) of rolling forests and farmland in the Peace River Valley, and is expected to affect the watershed in neighboring areas to the east and in Canada's far north.

Debate about the third dam to be built on the Peace River has raged since the 1960s with both supporters and opponents citing environmental sustainability and the project's impact on youth to make their arguments.

The provincial government calls it "a source of clean and renewable energy for over 100 years," but opponents say it will flood a sensitive natural environment and see the loss of valuable agricultural land.

The dam will help "build a future that our young people deserve in the province of British Columbia," provincial premier Gordon Campbell told a news conference in the remote north Monday.

The dam will help reduce greenhouse emissions even as provincial energy needs grow, and an expected one million more people arrive by 2030, added Campbell.

But the Peace Valley Environment Association argues the dam would destroy some of western Canada's best agricultural land, release carbon now stored in trees, disrupt a wildlife migration corridor and destroy heritage sites.

"It is misguided to destroy British Columbia river valleys to satisfy the energy demands of the United States," it said in a background document.

"The ability of the North to feed itself locally would be lost forever," wrote northern resident Carolyn Robe in a letter to a local newspaper. "How can it be considered green or clean to force the North to import food?"

But the project would be an economic boost, creating 35,000 direct and indirect jobs, provincial energy minister Blair Lekstrom told reporters.

Under provincial and federal law plans must pass independent environmental assessments, and if agreement is not reached with aboriginal organizations, the dam could be held up for years through court challenges.

Lekstrom acknowledged the fierce opposition to the dam. "We live in a free and democratic society... we have the ability to voice our views whether we are for or against something."

But Campbell said the dam was necessary to meet the provincial goal of energy self-sufficiency by 2016. "It is critically important that we start now. There will always be someone who counsels waiting. The time is now."