Enbridge Inc. handled a crude pipeline spill in Michigan like "Keystone Kops," the chairwoman of a U.S. investigator said Tuesday as environmental groups called for greater scrutiny of future projects.

A probe by the U.S. National Transportation Safety Board concluded Enbridge did not fix a defect on the pipeline when it was discovered five years earlier and control room staff responded poorly when Line 6B ruptured on July 25, 2010.

"Learning about Enbridge's poor handling of the rupture, you can't help but think of the Keystone Kops," said NTSB chair Deborah Hersman, referring to the incompetent policemen in silent films.

"Why didn't they recognize what was happening? What took so long?"

Enbridge (TSX:ENB) has billions in new pipeline projects and expansions in the works, including contentious plans to ship crude to the West Coast and to Central Canada.

Critics of the company's proposed Northern Gateway pipeline between Alberta and the B.C. coast as well as expansion to ship more Alberta crude eastward seized on the NTSB report as evidence the company should not be allowed to build those projects.

Hersman said Enbridge knew about a corrosion problem on Line 6B in 2005 — well before it ruptured and caused the most expensive onshore spill in U.S. history.

"Yet, for five years they did nothing to address the corrosion or cracking at the rupture site — and the problem festered."

The NTSB said it took 17 hours and 19 minutes for Enbridge staff to respond to alarms signalling a problem on the line in southern Michigan. And when they did respond, it was only after a worker with a local natural gas utility informed them of the spill.

Instead of stopping the flow, Enbridge staff misinterpreted the alarms and twice pumped more crude into the ruptured pipeline — representing about 81 per cent of the total spill, Hersman said.

More than three million litres of crude oil spilled into nearby wetlands, Talmadge Creek and the Kalamazoo River.

The total cleanup cost more than $800 million — more than five times the next most expensive onshore oil spill, Hersman said, citing figures from Enbridge and the U.S. Environmental Protection Agency.

She said poor regulatory oversight by the Pipeline and Hazardous Materials Safety Administration was also to blame.

"Delegating too much authority to the regulated to assess their own system risks and correct them is tantamount to the fox guarding the hen house," she said.

But Hersman said PHMSA did take the "necessary and important step" of proposing a $3.7-million fine against Enbridge last week.

In a release, Enbridge CEO Pat Daniel said the employees involved at the time of the spill were "trying to do the right thing."

"As with most such incidents, a series of unfortunate events and circumstances resulted in an outcome no one wanted."

He said the Kalamazoo River has since been re-opened for recreational use and that wildlife has returned to the area.

Stephen Wuori, Enbridge president of liquids pipelines, said the company has made changes after undertaking a thorough internal investigation.

"We will carefully examine the findings in the NTSB report to determine whether any further adjustments are appropriate."

NDP Natural Resources critic Peter Julian said the NTSB report was a "wake-up call" for Canada, especially after changes to the country's environmental review process passed Parliament last month as part of the Conservatives' controversial omnibus budget bill.

"The government is behaving in a profoundly irresponsible fashion," he said from Burnaby, B.C.

"And when you couple that with a company that has had repeated spills and seems to be, according to the NTSB, taking advantage of the fact that there isn't sufficient regulatory oversight, we've got a perfect storm."

Enbridge's Northern Gateway proposal would link oilsands crude to Asian markets, allowing Canadian companies to get a better price for the oil they produce. Enbridge has said it's confident it can operate the pipeline and marine terminal safely with top-notch procedures and equipment.

But First Nations groups, environmentalists and others fear that a spill from the pipeline or from the tankers that would travel in and out of the pipeline's terminus at Kitimat, B.C., could cause severe environmental damage.

"This should be the last warning signal we need that Enbridge cannot be trusted to build a tar sands pipeline through the largest intact temperate rainforest left on the planet," said Greenpeace campaigner Mike Hudema.

Enbridge also has big plans in the works to ship crude eastward from Alberta by expanding its existing system — including the one that broke in Michigan, 6B — and reversing the flow of Line 9 between Montreal and southern Ontario.

Gillian McEachern of Environmental Defence said Enbridge can't be trusted to ship crude through Ontario.

"The U.S. government found repeated instances of disregard for safety. The simple fact is if Enbridge can't ship tar sands oil safely in Michigan, why would it in Ontario?" she asked.

Jamie Ellerton of the group Ethical Oil said it's a "terrible thing" when pipelines spill, but "North Americans will continue to rely on fossil fuels for decades to come and pipelines are the safest and most effective way of transporting petroleum products to market."

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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.