Response teams attempt to collect oil on the Yellowstone River in Montana earlier this year after an oil pipeline ruptured and spilled into the river.

At around 10:30 a.m. on a Saturday in January 2015, a pipeline operator in a control room in Casper, Wyoming observed an imbalance in the line’s flow on a computer screen. Then an alarm started to sound. Within half an hour the operator shut the pipeline down, and 300 miles away, in Glendive, Montana workers scrambled to find a leak.

They were searching the banks of the iconic Yellowstone River.

Despite a mild Montana winter, the Yellowstone was frozen. With the ice, workers for the pipeline company did not see a sheen of oil across the water’s surface, which would normally indicate a leak. But below the ice the oil was loose, flowing into the river.

Overall, the leak spilled upwards of 30,000 gallons of Bakken crude into the Yellowstone. It spread under, onto and even through the ice.

The oil flowed with the current and eventually met an intake pipe for Glendive’s water supply. Testing of the town’s water later showed elevated levels of the hazardous compound benzene, a chemical present in petroleum.

For four days, a spill response team delivered bottled water to the town while it flushed its pipes clean.

The pipeline operator, Bridger Pipeline LLC, is based in Casper along with its sister pipeline operations company, Belle Fourche Pipeline. Both are owned by True Cos., a Wyoming family business that has a history of spills.

The cause of the spill has yet to be determined, but sonar readings showed a radial rupture in a 100-foot section of pipe that became unburied from the riverbed and sat exposed in the river. A company photo shows a deep crack, 1.5 inches at its widest point, wrapped halfway around the pipe. The 12-inch diameter pipeline was laid in 1955, but the section lying beneath the river was reburied in 1967.

Bridger Pipeline LLC, owned by True Cos. of Casper, Wyoming, ruptured and spills oil into the Yellowstone River in Montana.
Bridger Pipeline LLC, owned by True Cos. of Casper, Wyoming, ruptured and spills oil into the Yellowstone River in Montana.

Pipelines cross rivers at 2,841 locations nationwide, according to the Pipeline and Hazardous Materials Safety Administration, the agency responsible for their regulation. By law, the pipes must be buried under at least four feet of earth. The rule is the same for crossing a dynamic river like the Yellowstone as it is for a cornfield.

But after a number of recent pipeline oil spills into rivers, scientists and pipeline safety advocates have pushed to have pipelines buried far deeper than four feet. Even the oil industry appears to agree that four feet is too shallow.

The majority of the nation’s pipeline system was buried decades ago. Current industry standards are much stricter than then. Industry officials say they would never sink a shallow pipeline under a major river today, and some companies have begun reburying their river crossings at depths closer to 40 feet.

So far, however, the government’s pipeline regulator has declined to strengthen rules. Considering the number of pipeline incidents, spills like the one on the Yellowstone are rare, the agency says. But with thousands of miles of aging pipeline crossing rivers across the country, many say the lack of regulatory action puts U.S. rivers at serious risk.

Spills strike Yellowstone twice in four years

The 2015 spill wasn’t the first for the Yellowstone. In 2011, after a particularly bad winter, snowmelt caused the section of river near Laurel, Montana to flood three times in six weeks. During the third flood, Exxon’s Silvertip Line ruptured, and 1,500 barrels of oil were swept downstream by the swollen river.

Kim Charter’s farmland is downstream. It’s been in her husband’s family for more than 100 years. “It was a nightmare,” she said of the day the Silvertip spilled into the river.

When the flood waters receded, residents like Charter got their first true sense of the damage.

“When the water went down, everything was covered in black,” she said. Oil clung to tree branches and fences, running over everything on the property. Her neighbors complained of burning eyes and a foul smell.

Officials told them not to worry. “Nobody seemed to think there was anything that would harm anybody,” she said. But when the response team visited, they did so wearing hazmat suits.

Contractors wore hazmat suits during cleanup efforts for the 2011 Silvertip spill along Thiel Rd in Laurel, MT. (Tom Bearden/Flickr Creative Commons)
Contractors wore hazmat suits during cleanup efforts for the 2011 Silvertip spill along Thiel Rd in Laurel, MT. (Tom Bearden/Flickr Creative Commons)

Charter wasn’t surprised to hear about the spill in Glendive four years later, and she’s certain that the current depth-of-cover rule isn’t enough. Not on a river like the Yellowstone that floods and changes course. “It’s not sufficient to anybody,” she said of the four-feet rule.

Charter and her husband decided long before not to farm the land along the riverbed, preferring to leave it for wildlife and riparian vegetation important to the river’s health.

“You try to take care of things and you try to protect things, and then they go and wipe it out in a few minutes,” she said.

The Silvertip pipeline had been inspected by Exxon seven months before its failure, and was found to have between five and eight feet of cover. Investigators later found that the flood washed away that cover, exposing the pipeline to the pressure of debris that caused its rupture.

The ExxonMobil Pipeline Co. would eventually receive a $1 million penalty for doing a poor job maintaining the integrity of its line and failing to take into account the dynamics of the river conditions.

While PHMSA can issue fines following an accident, and order operators to rebury lines deeper after an incident, it does not order operators to rebury their lines proactively in areas prone to flooding and erosion.

Disasters under the radar

Oil spills into rivers aren’t disasters on the level of the BP Deepwater Horizon or Exxon Valdez spills, and they don’t draw the same level of international attention. According to PHMSA data, river spills between 1991 and 2012 accounted for 71,000 barrels of oil. The BP spill gushed 3.19 million barrels, and the Exxon Valdez more than 1.2 million.

Yet they are disasters nonetheless. Bridger Pipeline LLC’s Poplar Pipeline spill put Glendive’s water supply in jeopardy, a potential threat on rivers that run into reservoirs or are drawn on by the towns they pass through. And with the right flood, on the right stretch of river, pipeline crossings, too, can become catastrophes.

In October 1994, for example, the flooding San Jacinto River burst into flames. Four pipelines had spilled within three days, just outside downtown Houston. The lines carried crude oil, diesel, gasoline and an unnamed “highly volatile liquid.”

A raging fire burned on top of the river, with flames that at one point reached 60 feet into the air and engulfed barges, homes and businesses, according to newspaper accounts. The area had been evacuated as the river crested, which likely prevented casualties.

Ecological dangers to rivers, already threatened by agriculture, development, toxic runoff and other human impacts, also are considerable. In 1996, an exposed pipeline on the bottom of the Reedy River, in South Carolina, ruptured after years of corrosion.

With no flooding to disperse the oil, 22,800 barrels of diesel fuel rolled down the river, choking off everything in its path. The fuel killed an estimated 35,000 fish over a 23-mile stretch of water, according to the U.S. Environmental Protection Agency and the South Carolina Department of Natural Resources.

The EPA’s review of the Colonial Pipeline Co.’s settlement with the federal government stated that the company was aware of the pipeline’s exposure for several years but took no corrective action.

Mike Ruggles, a fisheries biologist with Montana Fish, Wildlife & Parks, has been studying the impact of the Exxon Silvertip spill on the Yellowstone’s fishery and ecosystem health. While not at liberty to discuss results due to his participation in an ongoing investigation of the damages caused by the spill, Ruggles said the river’s health has been damaged. As the water receded, oil sunk into holes along the floodplain and got buried, to be discovered later, Ruggles said.

Oil coats a crop of winter wheat at the high water mark at Yellowstone River Wildlife Management Area, near Billings, Montana after the 2011 Silvertip spill. (Sarah Clune/Flickr Creative Commons)
Oil coats a crop of winter wheat at the high water mark at Yellowstone River Wildlife Management Area, near Billings, Montana after the 2011 Silvertip spill. (Sarah Clune/Flickr Creative Commons)

There were “places where we were able to find it during the cleanup that was kind of surprising,” he said. “Heck, some of it was 10, 15 feet deep.”

Evaluating damage from the Poplar Pipeline spill will be more difficult, Ruggles said, because the lighter oil dispersed much more widely, and thus concentrations were lower.

Ruggles, too, is certain that four feet of cover isn’t nearly enough on the Yellowstone, and he worries about another pipeline rupture as a result. In his experience working on the river, he believes there’s parts of the bed which are shifting even 20 or 30 feet down.

Unlike on the Reedy River though, Ruggles said the ecological damage on the Yellowstone appears more subtle. “If you go out and ask people, there’s still fish,” he said. “There’s still wildlife. It wasn’t catastrophic as it could’ve been, but there was still injury.”

Old lines, washed out

The danger to rivers is amplified by the age of the pipeline network. The Poplar line was first installed in 1955, when workers dug a trench across the riverbed, laid the steel pipe, and covered it with silt.

The section that crosses the Yellowstone was reburied in 1967.

“A lot of the pipeline infrastructure is 50 or 60 years old or more,” said Sara Vermillion, assistant director of the physical infrastructure team at the Government Accountability Office.

In a 2013 report on PHMSA’s maintaining of data on pipelines, the government’s oversight committee recommended PHMSA make a greater effort to track and improve pipeline operators’ response times to spills on their lines.

By federal law, pipelines must be inspected every five years. In 2011, the last time the Yellowstone section of the Poplar was inspected, there was six feet of cover where it crossed the riverbed.

But much can change during one season on a rapid-moving river like the Yellowstone, let alone during five years. Rivers flood. New channels are created. Cover over the line gets scoured off, leaving pipelines hanging suspended and exposed in riverbeds. With no support, pipelines buckle and crack under their own weight. Or they are struck by fast-moving pieces of debris.

Karin Boyd, a geomorphologist and river science consultant who works on the Yellowstone and other western rivers, worries that federal regulations leave the safety decisions up to pipeline companies. It’s a process she called too arbitrary and without criteria based on a river’s strength or dynamism.

PHMSA says that’s just the point. Federal regulations are designed to be applied across the country, said agency spokesman Damon Hill, and local decisions on safety are left to the operator. “It’s not PHMSA’s job, it’s the operator’s job,” he said, regarding the decision about which rivers should require more than four feet of cover.

Congress questions four-foot rule

A male Cooper’s hawk (Accipiter cooperii) receives a thorough cleaning to remove oil threatening the bird’s health from International Bird Rescue staff at a bird rehab center in Billings, Mont., July 18. The bird of prey’s habitat intersects with areas affected by the Silvertip oil spill, which released approximately 1,000 barrels of oil into the high-flowing Yellowstone River July 1. The bird recovered from the oiling following the cleaning and was released into suitable non-oiled habitat in Montana. (USFWS/Flickr Creative Commons)
A male Cooper’s hawk receives a thorough cleaning to remove oil at a bird rehab center in Billings, Mont., July 18, 2011. The bird’s habitat was affected by the Silvertip oil spill, which released approximately 1,000 barrels of oil into the high-flowing Yellowstone River July 1. Following the spill Congress requested a study on the causes of pipeline failure. (USFWS/Flickr Creative Commons)

Following the Silvertip spill, Congress took note of the aging pipeline system, and the potential that the shallow depth may be dangerous. In 2012, it passed the Pipeline Safety, Regulatory Certainty, and Job Creation Act, which ordered PHMSA to conduct a study of oil spills at river crossings to determine if burial depth played a role. If regulators found that it did, the law also required stricter regulation.

Cynthia Quarterman, then the head of PHMSA, sent a report to Congress that December. The agency’s study found that depth of cover was a factor in 16 incidents, or only 0.3 percent of all oil spills. The majority were caused by material, equipment, and weld failure, according to the agency.

PHMSA “did not believe that any new legislative authority is needed,” Quarterman said in the letter.

Pipeline policy advocates, however, question the agency’s findings, particularly after a second Yellowstone spill less than three years after its report was completed.

Rebecca Craven, program director of the Pipeline Safety Trust, a nonprofit watchdog group, said there is little doubt river crossings are a common hazard for pipeline systems. “I don’t think there’s any question that scouring and erosion have played a role in a number of incidents,” she said.  

PHMSA has a history of incomplete and inaccurate studies. After the 2011 Exxon spill on the Yellowstone, then Montana Gov. Brian Schweitzer commissioned PHMSA to conduct a review of pipeline river crossings in the state.

“We tried to be pretty aggressive in what we were doing out in Montana, because we didn’t know whether any of the operators out there was going to experience the same problem.” Hill said of the review.

PHMSA compiled a list of the major river crossings in the state, and identified 42 that were laid with old-style trenching. Among them, PHMSA suggested fixing six. The Poplar line that later broke was not one of them. A 2011 inspection by Bridger Pipeline LLC had indicated adequate cover, so no remediation on the line was suggested.

PHMSA’s study for Congress also appears incomplete. Analysis of PHMSA oil spill data from 1991 to 2012, the years examined in the study, suggests that six oil spills caused by scouring, flooding or erosion were left out of the agency’s report. When asked, PHMSA suggested these spills did not meet the criteria for depth-of-cover issues, although it admitted some may have been overlooked. Incident reports reveal some of these spills occurred as a direct result of the cover eroding. Others were pipeline breaks in rivers during floods.

Analysis of PHMSA data shows that the loss of more than 13,000 barrels of oil and other hazardous liquids, including the solvent xylene, a byproduct of petroleum, didn’t make it into the report to Congress.

The worst of the missing incidents took place in June of 1991. A flood on the Brazos River in West Texas washed out a buried pipeline and 6,200 barrels of crude oil swept down the turbulent water, threatening a 180-mile stretch of river and floodplain.

“Reports from the field inspectors onsite described a thick, extensive oil slick on the turbulent water surface,” according to an analysis on the spill and cleanup produced by the Texas Railroad Commission, a state regulatory agency.

The flooding of the Brazos, normally a tame, winding river, made recovering the oil difficult. For the first two days following the spill, attempts to place containment booms and catch the oil failed as the raging waters overwhelmed them, according to the report.

Another spill that was not included in the PHMSA study occurred in 1995, in Kay County, Oklahoma, when the Texaco Pipeline Co.’s Cimarron line failed on the Salt Fork River during high water. More than 2,500 barrels spilled into the river. “High water conditions undercut buried pipe placing excessive stress on pipe,” read the narrative section of the incident report, describing the scouring process.

When asked about the missing spills, PHMSA said they were examined in the course of the study, but “didn’t meet what we were looking for to be involved,” Hill said.

While it is possible some incidents should have been included but weren’t, PHMSA’s data team dedicated significant time to the study, Hill said.

“We definitely looked at the incidents that occurred and we saw if anything that occurred was a result of depth of cover,” he said.

Modern industry standards far stricter than federal regulations

So far, the strongest initiative for increasing the depth of pipelines may be from industry itself. Today, pipeline companies can use horizontal directional drilling, a modern drilling method known in the industry as simply HDD. When Bridger Pipeline LLC replaced the section of pipe that caused the most recent Yellowstone spill, for example, it buried the line more than 40 feet under the riverbed, company spokesman Bill Salvin said. Exxon reburied its broken line under the Yellowstone, using HDD as well.

In Wyoming, the company also replaced two crossings under the North Platte River. “It’s certainly not as big as the Yellowstone, but it made sense,” to re-drill, Salvin said.

But there are more older pipelines than newer directionally-drilled ones, Salvin said. “If you look at all the pipelines in place in the United States, the one that ruptured under the Yellowstone is considered a medium-aged pipe,” even though it was installed 60 years ago in 1955.

And the hazard of older lines under rivers increases as they age. The Reedy River pipeline in South Carolina, and perhaps the Poplar line, were both weakened by age, as were pipelines in at least three of the incidents included in PHMSA’s report.

“You can have some very old pipelines that should be inspected but haven’t been,” said Sara Vermillion from the GAO. Or, she said, you can have lines from the 1950s and 60s that remain in good shape and are inspected frequently. Today, there’s no good way to tell.

Phillips 66, an oil company based in Houston, is aggressively reburying river crossings on its pipelines. In Montana, the company reburied 17 lines using HDD from 2011 to 2014, and says it has four more river crossings on tap for 2015, including two of the lines near Billings.

Dennis Nuss, a company representative, said it no longer uses trenching on major rivers. “Trenching a large river would actually cost more than an HDD,” he said. Today trenching is only an option “where pipelines cross smaller, shallower, slower streams that don’t experience the dynamic changes to banks and bottoms that occur on the Yellowstone.”

On April 9th, PHMSA reacted to the Poplar spill as it has reacted to river crossing spills in the past. An advisory bulletin was issued to the pipeline industry. The bulletin itself referenced five similar notices from the past; “Each of these bulletins followed an event that involved severe flooding that affected pipelines in the areas of rising waters,” it said. The bulletin then went on to issue 14 suggestions to operators.

One of them referred to using HDD: “… consider installing pipelines using horizontal directional drilling to help place pipelines below elevations of maximum scour,” the bulletin advised.

Booms collect oil from the 2011 Silvertip spill along Thiel Rd in Laurel, MT. Most of the oil — and cleanup — was concentrated on this roughly 1 mile stretch of road that runs alongside the river. (Tom Bearden/Flickr Creative Commons)
Booms collect oil from the 2011 Silvertip spill along Thiel Rd in Laurel, MT. Most of the oil — and cleanup — was concentrated on this roughly 1 mile stretch of road that runs alongside the river. (Tom Bearden/Flickr Creative Commons)

Yellowstone clean-up

On the Yellowstone, the most recent oil clean up has largely come to a halt. Bridger Pipeline LLC has recovered all the oil it can, and the rest will be left to weather, said Salvin, the company’s spokesman. As of April, approximately 22,000 gallons of oil, out of the 30,000 spilled, had been recovered, according to the company.

As for the rest, “mother nature will break that oil down,” Salvin said.

The company was lucky that the Bridger Pipeline broke in winter, when the river was frozen, he said, but  “there is absolutely no reason for any oil to be in the river.”

Ruggles, too, believes that luck has helped protect the Yellowstone. The oil that spilled out of the Silvertip line was a heavy crude, he notes, while the Poplar oil was lighter. If the Poplar spill had released heavier oil, with nowhere to disperse under the ice, it would have been a bigger problem.

Fortunately in the case of the Exxon Silvertip spill the heavier oil was dispersed by the floodwaters.

“We kinda got lucky at that one, and if it had happened at the Poplar spill we wouldn’t have been so lucky,” Ruggles said.

Kim Charter, the rancher who dealt with the 2011 spill, wouldn’t call it luck. She worries that a worse spill could happen in the future.

“We just hope that we never have to run into anything like that again,” Charter said.

CORRECTION: This story was updated on August 5, 2015 to correct the volume of oil spilled into the Yellowstone River in January — Ed.

— Andrew Graham is pursuing a master’s degree in Environmental Science Journalism from the University of Montana. He enjoys the campus full of topnotch researchers, and the backyard full of mountains.

Andrew Graham is reporting for WyoFile from Laramie. He covers state government, energy and the economy. Reach him at 443-848-8756 or at, follow him @AndrewGraham88

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  1. Controversy in North Dakota over an HDD pipeline under a slow moving section of the Missouri River – actually deemed a lake – is hard to understand.
    A complete failure of the government in explaining the extreme safety of the Standing Rock crossing.

    Activists know the pipeline is the safest one ever built, but are scaring people to stop oil transport.
    Mass Hysteria ignoring facts.

    Obama Administration suspends the permit for the crossing only encouraging not so smart people to brave a WINTER in North Dakota in protest.

  2. Hi,
    I’m looking for some more background on Silvertip “spill.” For instance where is the pipeline on Google Earth view of the bridge, the Riverside Park, the Google Earth visible pipe South of River, heading to across the Yellowstone, and crossing over the ditch by Sewer treatment plant.

    Any photos of when new Silvertip installed in HDD bore under river. Seems like they would be reassuring for Silvertip now,
    and very helpful way to visualize making ohter crossings of MT rivers to be more safe.

    Any evidence what Grade of Heavy Crude Oil was “spilled” up into the Yellowstone, four years back. Perhaps someone has an email address for Mike Ruggles!

    Thanks for helping,
    Bob Williams

    1. Mr. Meek,

      Thank you for noting the correct volume of oil spilled from the Bridger Pipeline in January (confused barrels with gallons). The story has been corrected. Very much appreciated.

      Andrew Graham

  3. Montana’s newly elected junior Senator, Steve Daines, is walking in closed ranks with Wyoming’s Senators to divert attention from the realities we are passing on to our grandchildren. Things like climate change or the half million abandoned mines that are already polluting 40 per cent of western watersheds. These threats are tantamount to mass abortion.

    Jim Parker