VANCOUVER - Concerns south of the border over oil tanker traffic from British Columbia have spurred a U.S. Coast Guard review of proposed increases in Canadian oil exports.

A legislative amendment proposed by Washington state Sen. Maria Cantwell and signed into law by President Barack Obama a couple of weeks ago gives the U.S. marine safety agency six months to conduct a risk assessment of the planned expansion of oil pipeline capacity to the West Coast.

While several proposed projects would see oil from the Alberta oil sands brought to the B.C. coast for export primarily to China, the legislation deals specifically with tanker traffic out of the Vancouver area.

"According to reports, Canada is poised to increase oil tanker traffic through the waters around the San Juan Islands and the Juan de Fuca by up to 300 per cent," said a statement issued by Cantwell's office.

"A supertanker oil spill near our shores would threaten Washington state's thriving coastal economy and thousands of jobs," the Democratic senator said in the statement. "This bill will provide crucial information for Washington coastal communities by requiring a detailed risk analysis...."

The Coast Guard will study the risk of transporting oil via supertanker, tanker and barge through the Salish Sea waterways, which encompasses U.S. and Canadian territorial waters between southern Vancouver Island and the mainland. It includes Juan de Fuca Strait, the Strait of Georgia, Haro and Rosario Straits and Puget Sound.

In order for ships to arrive at port in Vancouver, they usually sail through U.S. waters next to a national marine sanctuary.

The Coast Guard will examine which rules and regulations apply to oil tankers heading to B.C. ports, as well as analyze the toxicity of what is referred to in the legislation as "tar sands" oil — a derogatory moniker much opposed by the Canadian industry.

Cantwell said the diluted bitumen that will form part of the Canadian oil exports are likely to require special cleanup technology, and the Coast Guard will also assess the spill response capability.

There are two major oil pipeline proposals currently on the table in British Columbia.

Calgary-based Enbridge's Northern Gateway pipeline would transport oil from the Edmonton area to a tanker port in Kitimat, on the north coast.

But the U.S. legislation appears to affect mainly Kinder Morgan's proposal to expand the capacity of its existing oil pipeline from Alberta to the Vancouver area.

A call to TransMountain seeking comment was not returned.

The $4.3-billion TransMountain project would more than double the capacity of the 1,100-kilometre pipeline, from 300,000 barrels a day to 750,000. It would also allow the pipeline, which currently transports crude and refined oil from the Alberta oil sands, to transport diluted bitumen, a heavy oil critics say is more difficult to contain and clean-up in the event of a marine spill.

In operation since 1953, TransMountain runs from just outside Edmonton to Burnaby, and from there the oil is distributed through separate pipelines to local terminals, a refinery and the Westridge marine terminal in Port Metro Vancouver.

The Westridge terminal currently handles about eight vessels a month, five of them tankers. That would increase to about 28 a month, 25 of them tankers, under the proposed expansion plan.

If the application is successful, construction could begin in 2016 and additional oil could be flowing in 2017.

Vancouver city council has passed a motion opposing the expansion, and the mayor of Burnaby — the site of a 2007 spill from the pipeline — has spoken out against the project at a public meeting.

A spokesman for Transport Minister Denis Lebel said the two countries are constantly working together for the safe and secure transportation of natural resources across their shared border.

"Our government has been clear: If any project does not meet or surpass our stringent environmental standards, it will not proceed," spokesman James Kelly said in an email.

"Canada has already strengthened our strong record of environmental protection by requiring double-hulled tankers, mandatory pilotage and increasing navigational tools - and that work continues."

According to the Washington Research Council, the state has five major petroleum refineries of its own that process about 560,000 barrels of crude oil a day. Approximately 600 oil tankers and 3,000 oil barges travel through Puget Sound on an annual basis.

The commandant of the U.S. Coast Guard must submit recommendations to the House of Representatives' transport committee by the end of June.

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• Syncrude Upgrader and Oil Sands

  The refining or upgrading of the tarry bitumen which lies under the oil sands consumes far more oil and energy than conventional oil and produces almost twice as much carbon. Each barrel of oil requires 3-5 barrels of fresh water from the neighboring Athabasca River. About 90% of this is returned as toxic tailings into the vast unlined tailings ponds that dot the landscape. Syncrude alone dumps 500,000 tons of toxic tailings into just one of their tailings ponds everyday.

• Boreal Forest and Coast Mountains / Atlin Lake, British Columbia | 2001

  This area, located in the extreme northwest of British Columbia, marks the western boundary of the Boreal region. On the border of the Yukon and Southeast Alaska, the western flank of these mountains descends into Alaska's Tongass Rainforest and British Columbia's Great Bear Rainforest. Far from the oil sands, the greatest remaining coastal temperate and marine ecosystem is imminently threatened by the proposal to build a 750-mile pipeline to pump 550,000 barrels per day of oil sands crude to the coast. Once there, it would be shipped through some of the most treacherous waters, virtually assuring an ecological disaster at some point in the future.

• Tailings Pond in Winter, Abstract #2 / Alberta Tar Sands | 2010

  Even in the extreme cold of the winter, the toxic tailings ponds do not freeze. On one particularly cold morning, the partially frozen tailings, sand, liquid tailings and oil residue, combined to produce abstractions that reminded me of a Jackson Pollock canvas.

• Aspen and Spruce | Northern Alberta | 2001

  Photographed in late autumn in softly falling snow, a solitary spruce is set against a sea of aspen. The Boreal Forest of northern Canada is perhaps the best and largest example of a largely intact forest ecosystem. Canada's Boreal Forest alone stores an amount of carbon equal to ten times the total annual global emissions from all fossil fuel consumption.

• Tar Sands at Night #1 | Alberta Oil Sands | 2010

  Twenty four hours a day the oil sands eats into the most carbon rich forest ecosystem on the planet. Storing almost twice as much carbon per hectare as tropical rainforests, the boreal forest is the planet's greatest terrestrial carbon storehouse. To the industry, these diverse and ecologically significant forests and wetlands are referred to as overburden, the forest to be stripped and the wetlands dredged and replaced by mines and tailings ponds so vast they can be seen from outer space.

• Dry Tailings #2 | Alberta Tar Sands | 2010

  In an effort to deal with the problem of tailings ponds, Suncor is experimenting with dry tailings technology. This has the potential to limit, or eliminate, the need for vast tailings ponds in the future and lessen this aspect of the oil sands' impact.

• Tailings Pond Abstract #2 | Alberta Tar Sands / 2010

  So large are the Alberta Tar Sands tailings ponds that they can be seen from space. It has been estimated by Natural Resources Canada that the industry to date has produced enough toxic waste to fill a canal 32 feet deep by 65 feet wide from Fort McMurray to Edmonton, and on to Ottawa, a distance of over 2,000 miles. In this image, the sky is reflected in the toxic and oily waste of a tailings pond.

• Confluence of Carcajou River and Mackenzie River | Mackenzie Valley, NWT | 2005

  The Caracajou River winds back and forth creating this oxbow of wetlands as it joins the Mackenzie flowing north to the Beaufort Sea. This region, almost entirely pristine, and the third largest watershed basin in the world, will be directly impacted by the proposed Mackenzie Valley National Gas Pipeline to fuel the energy needs of the Alberta Oil Sands mega-project.

• Black Cliff | Alberta Oil Sands | 2005

  Oil sands pit mining is done in benches or steps. These benches are each approximately 12-15 meters high. Giant shovels dig the oil sand and place it into heavy hauler trucks that range in size from 240 tons to the largest trucks, which have a 400-ton capacity.

• Oil Sands Upgrader in Winter| Alberta Oil Sands | 2010

  The Alberta oil sands are Canada's single largest source of carbon. They produce about as much annually as the nation of Denmark. The refining of the tar-like bitumen requires more water and uses almost twice as much energy as the production of conventional oil. Particularly visible in winter, vast plumes of toxic pollution fill the skies. The oil sands are so large they create their own weather systems.

• Boreal Forest and Wetland | Athabasca Delta Northern Alberta | 2010

  Located just 70 miles downstream from the Alberta oil sands, the Athabasca Delta is the world's largest freshwater delta. It lies at the convergence of North America's four major flyways and is a critical stopover for migrating waterfowl and considered one of the most globally significant wetlands. It is threatened both by the massive water consumption of the tar sands and its toxic tailings ponds.

• Tar Pit #3

  This network of roads reminded me of a claw or tentacles. It represents for me the way in which the tentacles of the tar sands reach out and wreak havoc and destruction. Proposed pipelines to American Midwest, Mackenzie Valley, and through the Great Bear Rainforest will bring new threats to these regions while the pipelines fuel new markets and ensure the proposed five fold expansion of the oil sands.