“Looking for a needle in a haystack is difficult.” This is how Ron Kennedy, a reporter for the Calgary Herald, described the dangerous work of “Canada’s Pipeline Pilots” in 1959. Rough flying conditions made the work of aerial pipeline monitoring patrols “no job for a weak stomach and slow reactions.” Low-altitude flights above what was once the world’s largest oil pipeline system looking for leaks and spills were no simple task. But the work was necessary because large, long-distance oil pipelines have regularly spilled oil since they began operations in Canada in 1950. 
The hazards of this work were plenty. The small Cesna-180 planes violently bounced like a bucking bronco in the turbulent air. One pilot took to wearing a crash helmet to protect his head from hitting the roof of the cockpit. Migratory birds could crash through the windshield. Adverse weather could easily bring down such small planes.
In the mid-twentieth century, Interprovincial Pipe Line Company (now Enbridge, Inc.) hired dozens of veteran bush pilots to fly small planes along the right-of-way for its enormous oil pipeline system. By 1959, the Interprovincial pipeline spanned thousands of kilometres from Edmonton to Toronto crossing fields, forests, muskeg, and rivers. It even crossed the Great Lakes at the Straits of Mackinac in Michigan. And since the pipeline opened in 1950, it suffered leaks and spills. The first known spill was reported in November 1950 in Minnesota.  Aerial patrols were a key component of the company’s monitoring practices to find and remedy oil spills.
Pilots described oil pipeline spills as “the blackest of black” or a “living black” they could see from the skies. Occasionally, they would land for closer inspection. When they spotted large spills, they radioed the nearest pump station to alert operators to close the line and begin the recovery and clean-up process.
For nearly 70 years, pipeline companies have had to confront the persistent hazard of onshore oil spills. To begin to understand this complicated history, I’ve published a new open-access article in Canadian Historical Review that offers the first quantitative analysis of historical oil spills on Canada’s system of long-distance pipelines. Using incident reports that cover a period from 1961 to 1996, the article makes the following arguments:
- Oil spills have always been a frequent hazard associated with the development and operation of oil pipelines in Canada.
- Oil pipeline spills are an endemic characteristic of complex enviro-technical systems built primarily for economic efficiency rather than environmental protection.
- Though frequent, oil pipeline spills have been a proportionally small fraction of the total oil delivered on Canadaâ€™s long-distance pipelines, but, in absolute terms, this has meant the uncontrolled release of many millions of litres of oil into the environment.
Between 1961 and 1996, pipeline companies reported 560 oil spill incidents to federal regulators.
This new research, I hope, will provide necessary context for understanding the legacies of oil pipeline development and some of the environmental consequences of Canada’s transition to a high-energy hydrocarbon economy in the second half of the twentieth century. For more information on this research project, visit “Silent Rivers of Oil: A History of Oil Pipelines in Canada Since 1947.”