The lieutenant governor of British Columbia announced Tuesday that all types of mining and oil and gas development "will not be permitted" in the province's portion of the Flathead Valley.

It was news that was well received in Montana.

"It's pretty significant," said Dave Hadden of the conservation group Headwaters Montana.

The announcement came during the "Throne Speech," an annual address that identifies the provincial priorities for the coming year.

"A new partnership with Montana will sustain the environmental values in the Flathead River Basin in a manner consistent with current forestry, recreation, guide outfitting and trapping uses," British Columbia Lt. Gov. Steven Point said.

"Mining, oil and gas development and coalbed gas extraction will not be permitted in British Columbia's Flathead Valley."

Montana Gov. Brian Schweitzer said Tuesday he will sign a comprehensive "memorandum of understanding" with British Columbia Premier Gordon Campbell next week in Vancouver, B.C. That document will halt ongoing exploration work and prohibit future development.

Schweitzer said the agreement was the result of five years of mostly quiet and often-delicate negotiations aimed at limiting development in the river drainage just north of Glacier National Park.

"We've agreed there will be no gold mining, no coal-bed methane and no coal mining in the Flathead on the Canadian side," Schweitzer said.

Companies with money already invested in leases or exploration could be compensated through the Canadian and U.S. governments, Schweitzer said, although details have not been worked out.

He credited the breakthrough to "a bold move by Premier Campbell."

Schweitzer added: "I can say of all of the things I've managed to accomplish, there's none I'm more proud of."

Since the 1980s, Montana has resisted a series of proposals for mining and oil and gas development in the Canadian Flathead, largely because the basin's waters flow south into the North Fork Flathead drainage, along the west boundary of Glacier Park and into Flathead Lake.

There are concerns over pollution along with impacts on fish and wildlife.

"People in the Flathead Valley place a very high value on Glacier Park and clean water," Hadden said. "The B.C. government announcement represents an important opportunity for Montanans to work with B.C. to protect the entire North Fork Flathead watershed, including unfinished conservation on the U.S. side of the border."

Several years ago, the B.C. provincial government imposed a moratorium on coal mining in the lower third of the Canadian Flathead, but that was regarded as a temporary, stopgap protection, Hadden said.

Other Montana conservation groups applauded Point's remarks.

"As the world's first international peace park, Waterton-Glacier is more than just a national park," said Will Hammerquist, Glacier program manager for the National Parks Conservation Association. "It is an icon of international cooperation, peace between nations, and the special relationship between Canada and the United States. Today's announcement honors this vision and is an opportunity to begin a new era of transboundary cooperation in the Flathead Valley and surrounding Crown of the Continent ecosystem."

According to Tim Preso, staff attorney for the law firm Earthjustice, "Today's announcement marks an important step forward to protect the undeveloped, low-elevation valley in southern Canada, where grizzly bears, lynx and wolverines still roam beside pure water that nurture native trout. We are pleased that British Columbia now recognizes what the U.N. World Heritage Committee recently reaffirmed: The wild Flathead Valley is a treasure more precious than coal or gold."

The Associated Press contributed to this story.