Last September, a farmer harvesting wheat in North Dakota smelled crude oil in his fields. That was the first indication anyone had that a Tesoro pipeline had ruptured and spewed some 20,000 barrels of oil into the environment.

Tesoro says it has beefed up its monitoring of the pipeline, as the pressure sensors it had installed before the spill did not detect the slow seep of oil, even though it had soaked a surrounding area the size of six football fields.

This may sound like an outlier case, but as it turns out, it is pretty much the industry standard. According to an investigation by the Wall Street Journal, it is all too common that oil companies are the last to know when their pipelines spring a leak.

Coming just a week after Canada’s foreign minister traveled to Washington, D.C., and called on the Obama administration to make a decision on Keystone XL pipeline, the results of the paper’s analysis contradict the oil industry’s claims that the safety of pipelines can be ensured through existing measures.

According to the Wall Street Journal, which looked at Pipeline and Hazardous Materials Safety Administration data on 251 spills that occurred on private property since 2010, the industry’s pipeline monitoring equipment was the first to detect a leak in just 19.5 percent of incidents.

The other 80 percent of the time leaks are generally discovered by people — local residents and landowners, like that North Dakota wheat farmer, as well as on-site employees of the oil and pipeline companies.

Pipelines are proliferating across North America and this study confirms what even casual observers already know: there are serious questions about how safe oil pipelines really are. Much tighter regulations are clearly needed, since oil and pipeline companies are routinely demonstrating their inability to monitor themselves to ensure the safety of their operations in our communities.

As the Wall Street Journal points out, there are better pipeline monitoring systems available, though federal regulations do not always require their use. TransCanada, for instance, has already said it won’t be using some of the more advanced leak detection systems on Keystone XL, if it gets approved. With that in mind, if the pipeline goes ahead, it won’t be a matter of if, but when, the next farmer has to alert an oil pipeline company to oil in his fields.

Read the Wall Street Journal investigation: High-Tech Monitors Often Miss Oil Pipeline Leaks.

Image credit: Pipeline leak cartoon via Shutterstock.