VANCOUVER - More than two and a half years after a Canadian pipeline rupture spilled heavy oil into a Michigan River, the U.S. Environmental Protection Agency is ordering Calgary-based Enbridge (TSX:ENB) to perform additional dredging to remove submerged oil.

The agency said it has repeatedly found oil in sections of the Kalamazoo River.

"The dredging required by EPA's order will prevent submerged oil from migrating to downstream areas where it will be more difficult or impossible to recover," the EPA said in a statement issued Thursday.

The agency is also ordering Enbridge — proponent of the controversial Northern Gateway pipeline through northern British Columbia — to maintain sediment traps throughout the river to capture oil outside the dredge areas.

The agency gave the company 15 days to provide a work plan, and said dredging should begin this spring.

The July 2010 spill near Marshall, Michigan, has dogged the company as it proceeds through a federal review of the Northern Gateway to deliver oil sands products to a tanker port in Kitimat, B.C.

The ability to clean-up diluted bitumen from Alberta's oil sands has been raised at the hearings by project opponents.

The American environmental agency issued a searing report last year criticizing the company's spill response.

A letter sent Thursday to Rich Adams, vice-president of operations for Enbridge's U.S. operations, from EPA co-ordinator Ralph H. Dollhopf, said the oil mixed with river sediment and organic matter had turned to sludge, "making it difficult to find and recover."

EPA documents note that they met twice with company officials about the administrative order.

"Enbridge's comments challenged the validity and interpretation of the data relied upon by U.S. EPA in making its determination ...," said a 36-page response.

In it, the agency discounts Enbridge's suggestion that allowing the oil to biodegrade is the best option for dealing with the remaining oil.

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  • 10. Oil And Gas Accounts For 4.8 Per Cent Of GDP

    The oil and gas industries accounted for around $65 billion of economic activity in Canada annually in recent years, or slightly less than 5 per cent of GDP. Source: <a href="http://www.ceri.ca/docs/2010-10-05CERIOilandGasReport.pdf" target="_hplink">Canada Energy Research Institute</a>

  • 9. Oil Exports Have Grown Tenfold Since 1980

    Canada exported some 12,000 cubic metres of oil per day in 1980. By 2010, that number had grown to 112,000 cubic metres daily. Source: <a href="http://membernet.capp.ca/SHB/Sheet.asp?SectionID=9&SheetID=224" target="_hplink">Canadian Association of Petroleum Producers</a>

  • 8. Refining Didn't Grow At All As Exports Boomed

    Canada refined 300,000 cubic metres daily in 1980; in 2010, that number was slightly down, to 291,000, even though exports of oil had grown tenfold in that time. Source: <a href="http://membernet.capp.ca/SHB/Sheet.asp?SectionID=7&SheetID=104" target="_hplink">Canadian Association of Petroleum Producers</a>

  • 7. 97 Per Cent Of Oil Exports Go To The U.S.

    Despite talk by the federal government that it wants to open Asian markets to Canadian oil, the vast majority of exports still go to the United States -- 97 per cent as of 2009. Source: <a href="http://www.nrcan.gc.ca/statistics-facts/energy/895" target="_hplink">Natural Resources Canada</a>

  • 6. Canada Has World's 2nd-Largest Proven Oil Reserves

    Canada's proven reserves of 175 billion barrels of oil -- the vast majority of it trapped in the oil sands -- is the second-largest oil stash in the world, after Saudi Arabia's 267 billion. Source: <a href="http://www.ogj.com/index.html" target="_hplink">Oil & Gas Journal</a>

  • 5. Two-Thirds Of Oil Sands Bitumen Goes To U.S.

    One-third of Canada's oil sands bitumen stays in the country, and is refined into gasoline, heating oil and diesel. Source: <a href="http://www.nrcan.gc.ca/statistics-facts/energy/895" target="_hplink">Natural Resources Canada</a>

  • 4. Alberta Is Two-Thirds Of The Industry

    Despite its reputation as the undisputed centre of Canada's oil industry, Alberta accounts for only two-thirds of energy production. British Columbia and Saskatchewan are the second and third-largest producers. Source: <a href="http://www.nrcan.gc.ca/statistics-facts/energy/895" target="_hplink">Natural Resources Canada</a>

  • 3. Alberta Will Reap $1.2 Trillion From Oil Sands

    Alberta' government <a href="http://www.huffingtonpost.ca/2012/03/27/alberta-oil-sands-royalties-ceri_n_1382640.html" target="_hplink">will reap $1.2 trillion in royalties from the oil sands over the next 35 years</a>, according to the Canadian Energy Research Institute.

  • 2. Canadian Oil Consumption Has Stayed Flat

    Thanks to improvements in energy efficiency, and a weakening of the country's manufacturing base, oil consumption in Canada has had virtually no net change in 30 years. Consumption went from 287,000 cubic metres daily in 1980 to 260,000 cubic metres daily in 2010. Source: Source: <a href="http://membernet.capp.ca/SHB/Sheet.asp?SectionID=6&SheetID=99" target="_hplink">Canadian Association of Petroleum Producers</a>

  • 1. 250,000 Jobs.. Plus Many More?

    The National Energy Board says oil and gas employs 257,000 people in Canada, not including gas station employees. And the Canadian Association of Petroleum Producers says the oil sands alone <a href="http://www.capp.ca/aboutUs/mediaCentre/NewsReleases/Pages/OilsandsaCanadianjobcreator.aspx" target="_hplink">will grow from 75,000 jobs to 905,000 jobs by 2035</a> -- assuming, of course, the price of oil holds up.