Mitch Friedman, head of Conservation Northwest, a Washington-based group whose advocacy reaches into British Columbia, has an unusual way of estimating the strength of the environmental movement: by the number of "activists per square mile." In B.C., he says, that number is "very low -- there are whole mountain ranges without a single citizen watchdog, much less a professional."

That's one of the difficulties U.S. environmentalists face in rural B.C., along with a kind of "xenophobia" -- a generalized local hostility to outsiders, especially in isolated communities, and particularly if those outsiders are not Canadians, says another Western environmentalist. Canadian Prime Minister Stephen Harper's administration is also pressuring foundations to withdraw their support for politically active environmental groups. Nevertheless, a few U.S. environmentalists are making significant efforts in B.C. Here's a sampler:

Rivers Without Borders

Founded in 1999 as the Transboundary Watershed Alliance, this group now has six staffers and consultants based in Washington, Alaska and B.C., sponsored by the Tides Foundation's branches in both countries. They're trying to protect seven major rivers that straddle the B.C.-Alaska border, focusing particularly on organizing Alaskan officials, commercial fishermen and First Nations to battle a proposal to greatly expand the old Tulsequah Chief Mine on a B.C. stretch of the Taku River, which flows to the coast near Juneau and supports the largest salmon runs in Southeast Alaska. The group's executive director, Will Patric, says the transboundary rivers are "hugely important for wild salmon, biodiversity and First Nations."

Round River Conservation Studies

This scientific group played a key role in the "Great Bear Rainforest Campaign," in which advocates including Greenpeace and many First Nations persuaded the B.C. government to protect millions of acres of coastal forest starting in the 1990s. Based in Salt Lake City, Round River also works with the small Taku River Tlingit First Nation in northwestern B.C. on the watershed of the Taku River. Round River head Dennis Sizemore uses a strategy called Traditional Ecological Knowledge, which involves talking to Native elders, hunters and anglers to determine which parts of the landscape are most valuable for the ecosystem and various human uses. Recently, the group helped the Tlingit negotiate with the B.C. government on a land-use plan that protects millions of acres of roadless forest in the Taku watershed, and now it hopes to limit mining impacts on the Taku River.

Conservation Northwest

Founded in 1989, this Bellingham-based group has three representatives on contract in B.C., along with 18 staffers who work mostly in Washington state, attempting to preserve connectivity between core habitats for lynx, grizzly bears and other wildlife. A few years ago, they helped persuade the B.C. government to limit logging and roads in more than 5 million acres of mountain caribou habitat near the U.S. border. Now they're working with First Nations communities and others in southwestern B.C.'s grizzly bear and salmon country, trying to block the proposed $1.1 billion New Prosperity open-pit gold mine.

Southeast Alaska Conservation Council

Founded in 1970, this Juneau-based group was a force in reducing old-growth logging in the Tongass National Forest and has focused lately on mining in B.C. With 13 staffers, it's pressuring Alaska officials to do baseline studies of water quality in rivers that might be impacted by new B.C. mines, while working to build a coalition of First Nations and groups on both sides of the border to oppose the mining rush.

National Geographic Society

For nearly 125 years, the Washington, D.C.-based Society has funded scientific explorers to document wilderness -- and threats to it -- worldwide. Today, 14 roaming staffers in a special program called "Explorers in Residence" carry out that mission; two of them -- J. Michael Fay and Wade Davis -- live seasonally in northwestern B.C. and document the mining rush there.