"This legislation represents a monumental achievement," said Municipal Affairs and Housing Minister Chris Hodgson, whose bill is based on recommendations by an advisory panel of municipalities, developers and environmentalists.

"Some 1,000 acres of sensitive land have been secured so natural areas can be protected. This is being accomplished through land donations and exchanges for provincially owned developable lands off the moraine," said Hodgson in a statement.

He also pledged C$75 million in cash and land for the preservation of the site through the creation of the Oak Ridges Moraine Foundation. This non-profit corporation will create trails and develop programs for environmentally-friendly practices.

"This announcement came as a surprise and it's a critical step in getting this vital land permanently protected," U.S. environmentalist Robert F. Kennedy said, a few hours before addressing a sold-out Toronto fundraiser dinner for the conservation of the moraine.

Kennedy said he became involved in the project two years ago because of the similarity of the moraine with the protection of the water supply in New York region.

"We are delighted, but the province is going to need financial help from the federal government... because (the moraine) is a national resource," he told Reuters.

Glenn de Baeremaeker, president of Save the Rouge Valley, one of the most vocal groups against urban sprawl, said the moraine is the life source of 65 rivers connected Lake Ontario, offering a water supply for some 250,000 Ontarians.

"It the most ecologically important area in southern Ontario. It's the number one area that we must protect if we want clear water in our rivers," he told Reuters.

A spokeswoman for the minister said developers who want to build on the moraine might have the chance to do so during a governmental review in ten years. But this opportunity will be limited to 8 per cent of the region, already populated with small towns and summer cottages.

De Baeremaeker said the Conservative government acted with common sense. "It was politically smart. There is an overwhelming public support for the Oak Ridges Moraine and it's located in a big Conservative stronghold," he said.

The next provincial elections are not expected before two years but the Conservative government, trailing the Liberals in the polls, might benefit from this "green legacy."