Yellowstone River

An aerial view of the Yellowstone River at Glendive, Montana, where an oil pipeline ruptured on Jan. 17, 2015. (Photo: brewbooks/Flickr)

It's surprisingly easy to overlook news about a pipeline spill in North America, especially as common as they've become over the past five years. Unless you happen to live near the latest oil, gas or wastewater leak, the stories can run together and seem to dissipate over time.

So when a Montana oil pipeline burst on Jan. 17, releasing about 50,000 gallons into the Yellowstone River for the second time in less than four years, many Americans took fleeting notice. It wasn't even the first big U.S. pipeline crisis of 2015, thanks to a North Dakota line that began losing oil-field wastewater in early January. That spill totaled 3 million gallons, officials revealed on Jan. 21 — almost triple a similar one in 2014, and by far the worst wastewater leak of North Dakota's current Bakken oil boom.

These are the latest in a spate of U.S. and Canadian pipeline leaks, fueled by ongoing oil booms in Alberta and North Dakota. The Yellowstone spill hints at how dangerous crude oil can be when it infiltrates an important waterway, especially one that tends to ice over in winter. Not only did this spill add known carcinogens to the water supply in Glendive, Montana — tests showed benzene levels three times the federal limit — but it also dumped more than 40,000 gallons of Bakken crude under an ice layer ranging from an inch to several feet thick, complicating cleanup efforts.

The video below, released by Montana officials on Jan. 21, shows a drone's-eye view of the icy Yellowstone River spill site. The ruptured pipeline was reportedly buried about 8 feet below the river, but sonar surveys indicate a segment of it is now exposed on the riverbed.

Grist for the spill

Some other recent spills have been even worse, not just because they spilled a greater volume but because they spilled diluted bitumen, aka "dilbit." Bitumen is a tarlike substance produced in the Alberta oil sands, and it must be diluted to flow through pipelines. While conventional crude oil floats on water, dilbit sinks to the bottom — as some Americans learned the hard way during major dilbit spills into Michigan's Talmadge Creek in 2010 and near Mayflower, Arkansas, in 2013. Those spills totaled 843,000 and 200,000 gallons of heavy oil, respectively, and both are enduring lengthy cleanups.

Big pipeline spills aren't exactly rare. About 126,000 gallons of crude oil escaped a North Dakota pipeline in 2010, for example, as did 600,000 gallons from a pipeline near Chicago later that year. The 2011 Yellowstone spill released 63,000 gallons, and this year's followup was only a few thousand gallons less. Between 2008 and 2013, U.S. pipelines spilled an average of 3.5 million gallons of hazardous liquids per year, according to federal data. That includes not just various types of oil but also briny, potentially toxic wastewater from the drilling process; while this month's brine spill was North Dakota's largest, the state also suffered spills of 1 million gallons in 2014 and 865,000 gallons in 2013.

Some pipeline problems, including the one behind this month's Montana spill, are at least partly due to aging infrastructure. That pipeline was 55 years old and last inspected in 2012. It was deemed a moderate risk for failure in 2011 by government reports, which cited recent changes in the river's path that could raise the risk of erosion. (The 2011 Yellowstone River spill was caused by debris in the flooded river, another potential pitfall of building pipelines near waterways.)

Similar aging issues plague many other fuel pipelines around the country, including some natural gas lines that have sprung thousands of leaks below major U.S. cities. The pipeline that caused a deadly 2010 explosion in San Bruno, California, for example, was also more than 50 years old.

2010 Michigan oil spill

Oil clings to plants in Michigan's Kalamazoo River after an 843,000-gallon oil spill in 2010. (Photo: Bill Pugliano/Getty Images)

Carved in Keystone

While pipeline safety has generally improved since last century, calamities aren't necessarily limited to old pipes. In 2011, about 21,000 gallons of oil leaked into a South Dakota pumping station from TransCanada's relatively new Keystone pipeline, which had begun commercial crude delivery just nine months earlier. And that was on the heels of 10 smaller leaks, all in less than a year of operation.

That pipeline is part of TransCanada's Keystone Pipeline System, a 2,639-mile (4,247-kilometer) network to carry oil from Alberta to the U.S. Midwest and Gulf Coast. It began delivering in 2010, but the company has been lobbying the U.S. since 2008 to approve a 1,180-mile addition — known as Keystone XL — that would cut more southeast from Canada, passing through Montana, South Dakota and Nebraska before linking to existing lines near Kansas. An earlier route for Keystone XL was rejected in 2012 due to ecological risks, but TransCanada's newer plan has still faced stiff resistance from environmental advocates as well as some residents in its proposed path (see map below).

Keystone XL pipeline map

Criticism of Keystone XL has largely focused on how the pipeline could affect climate change, since it would represent a major investment in developing carbon-heavy oil sands rather than renewable energy sources. Increased greenhouse gas emissions probably do represent the project's greatest overall risk, but local opposition is not surprisingly often more concerned with the possibility of a dilbit spill.

A leak from Keystone XL could introduce benzene, toluene other dangerous toxins into a swath of water supplies across the Great Plains. That includes the Ogallala Aquifer, the largest groundwater reserve in western North America as well as the source for more than three-quarters of all water used in the High Plains area.

To be fair, a spill probably wouldn't threaten the entire Ogallala. TransCanada points out more than 80 percent of the aquifer lies west of the updated Keystone XL route, and a 2013 report by the Nebraska state officials suggested a spill "would likely have impacts on groundwater at a local level, rather than a regional level." That's little solace for local residents, though, especially given the long-term harm from recent leaks elsewhere. Even if a spill didn't ruin the Ogallala, it could still damage nearby ecosystems, farmland and freshwater. While most landowners on the pipeline's path have agreed to terms with TransCanada, the company is now pursuing dozens of holdouts via eminent domain.

Keystone Pipeline

Part of the existing Keystone Pipeline System near Pleasant Hill, Nebraska, in 2013. (Photo: shannonpatrick17/Flickr)

Pipe dreams

Despite having many advocates in Congress, Keystone XL's prospects remain hazy. It needs approval from the U.S. State Department since it would cross a national border, yet the U.S. Environmental Protection Agency has raised concerns about its impact on climate change — and about the State Department's own environmental impact assessment, calling the review "insufficient" in a 2013 letter. The pipeline would undoubtedly have economic benefits, but in addition to disputing the extent of those benefits, critics often cite the economic risks of a dilbit spill, not to mention climate change.

President Obama has also increasingly expressed reservations about the pipeline, leading many to expect him to veto an attempt by Congress to force the project's approval. Obama has vowed to reject it if it would significantly add to climate change, a question that hinges partly on whether a similar amount of oil would be produced and burned — and thus release its greenhouse gases — regardless of Keystone XL. Oil trains have become a popular alternative to pipelines in the U.S., growing from 9,500 rail-carloads of oil in 2008 to 415,000 in 2013, an increase of 4,200 percent. But they've also revealed their own risks with a series of derailments, including the catastrophic Lac-Megantic crash in 2013.

Bakken oil may be especially dangerous to transport, according to a 2014 report by U.S. regulators, because it "has a higher gas content, higher vapor pressure, lower flash point and boiling point and thus a higher degree of volatility than most other crudes in the U.S., which correlates to increased ignitability and flammability." Recent rail disasters have prompted efforts to tighten safety regulations in both the U.S. and Canada, but oil trains will likely continue running in any case — both with light Bakken crude and with the sulfurous dilbit Keystone XL would carry south from Alberta.

This month's Yellowstone oil spill was Bakken crude, not the Canadian dilbit spilled in Michigan and Arkansas. Either type of oil poses a wide range of dangers, though, and recent history illustrates the difficulty of keeping oil and other hazardous materials inside roughly 2.6 million miles of U.S. pipelines. Plummeting oil prices have also removed some luster from Keystone XL and other projects in the past six months, highlighting the economic volatility that can make any major pipeline a risky investment.

The only real solution to pipeline spills and oil-train crashes is to find a safer, more sustainable energy source than petroleum — and, fortunately, the renewable power sector is already growing like weeds. Yet weaning off oil will inevitably take a long time, especially with U.S. and Canadian oil fields still booming. So in the meantime, the least we can do is not look away — and maybe even muster sustained interest — the next time an American river starts filling up with oil.

Russell McLendon ( @russmclendon ) writes about humans and other wildlife.