A sobering critique of America’s pipeline spill response efforts was delivered in a new study released Tuesday, concluding they aren’t adequate when it comes to spills involving sludgy crude oil pumped from the Canadian tar sands.

The 144-page report‘s main message is that the thick type of oil called diluted bitumen, or “dilbit,” initially behaves like conventional oil in the first few days following a spill but then quickly degrades, or weathers, into a substance so chemically and physically different that it defies standard spill responses.

The report recommends tailoring spill response plans by oil type, a stark contrast to the reassurances often uttered by energy companies that dilbit doesn’t need special regulations. In recent years, the volume of dilbit coursing through American pipelines has increased steadily, from 250 million barrels in 2013 to 300 million barrels in 2014.

Conducted by the National Academies of Sciences, Engineering and Medicine, the investigation released Tuesday offers the most comprehensive analysis to date of dilbit spill properties, environmental and health impacts and effectiveness of response methods.

“We feel that we have put forward practical and pragmatic recommendations and we are optimistic that these recommendations will be taken in that spirit,” said Diane McKnight, chair of the National Academies committee that developed this report.

The report, requested in May 2014 by regulators at the U.S. Department of Transportation in response to a Congressional inquiry, comes more than five years after the destruction of dilbit spills first hit the national spotlight, following the country’s largest inland oil spill in Michigan. An Enbridge pipeline rupture in July 2010 released more than 1 million gallons of dilbit, mostly in the Kalamazoo River, where it dirtied the water and impacted the surrounding vegetation and wildlife. The massive spill displaced 150 families, forced a two-year closure of a section of the river and cost pipeline operator Enbridge at least $1.2 billion to clean up.

An InsideClimate News investigation of the accident—”The Dilbit Disaster: Inside the Biggest Spill You’ve Never Heard Of“—won the 2013 Pulitzer Prize for National Reporting. In 2013, another pipeline ruptured in Mayflower, Ark., fouling a suburban neighborhood.

“The National Academy of Sciences is skewering the industry’s ‘oil is oil’ talking point—making it clear that diluted bitumen is a different beast altogether and needs to be treated as such,” Anthony Swift, Canada program director for the green group Natural Resources Defense Council, said in a statement Tuesday.

“Canadian oil sands crudes have been transported safely in the U.S. for more than 40 years,” Sabrina Fang, a spokeswoman for the industry trade group American Petroleum Institute, wrote in an email to InsideClimate News. “All crude oils have to meet the same criteria when put in a pipeline, which protects the pipeline and the quality of all transported crudes…. If a release does occur, pipeline operators are prepared to respond quickly and effectively, working with local emergency responders.”

“The prospect of a release of crude oil into the environment through a pipeline failure inherently raises a number of concerns,” wrote the study authors, a collection of nearly a dozen oil spill experts from academia and industry in the U.S. and Canada.

“These concerns include not only minimizing a number of possible long-term environmental impacts but also protecting the safety of responders and the public during and after the spill response,” the study continued. “When all risks are considered systematically, there must be a greater level of concern associated with spills of diluted bitumen compared to spills of commonly transported crude oils.”

‘Act Quickly and Decisively’

When a pipeline ruptures, often the people impacted do not know it is dilbit.

“In the U.S, and many other places, once the oil spills, the first responders do not know what it is,” said Merv Fingas, a study author and an Alberta-based energy consultant. “They are told it is crude,” not what kind of crude.

Once on the scene, the oil cleanup crew still won’t know the oil type by looking at it, explained Fingas, because dilbit and the more commonly transported oil, called conventional medium and light crude, look exactly the same—”until a few days pass.”

Dilbit is a mix of heavy bitumen, or oil sands, extracted from the Alberta oil patch. It emerges with the consistency of peanut butter and it is then thinned with diluents to make it easier to transport. If dilbit spills, the diluents evaporate, leaving behind a tarry goo that sinks in water and is very sticky.

Here’s the rub: once it becomes clear to responders that the oil at hand is dilbit—because it has visibly started to degrade—it is likely already too late to effectively clean it up, according to the recent report.

“The big message is to act quickly and decisively,” said Bob Sussman, an environmental consultant at Sussman and Associates and one of the study authors. “In the hours and days following a dilbit spill, it is critical to contain and remove as much of the material as possible.”

The narrow window of time when dilbit most looks and acts like conventional oil offers the best opportunity to employ conventional response methods, such as burning it or using equipment called booms and skims to contain and collect oil from water.

Once dilbit starts to weather,  it sinks in the water, rendering most oil recovery methods useless.

“This important study from the National Academy of Sciences confirms what the tragic spills in Michigan’s Kalamazoo River and Mayflower, Arkansas have already shown us: transporting heavy tar sands oil crude presents unique and unacceptable risks to wildlife and habitat,” Jim Murphy, the National Wildlife Federation’s senior counsel, said in a statement.

The report also highlighted several key scientific gaps concerning weathered dilbit, including how little is known about its threat to public health due to long-term exposure by air and water.

Better Communication Is a Must

The study authors detailed several policy recommendations aimed at improving dilbit spill preparedness, response and cleanup.

Oil companies need to inform regulators  which type of crude oil they are transporting  in every pipeline segment before a spill occurs, the report recommended.

Operators should also design different spill response plans depending on the oil type, the authors advised. And when a spill does occur, operators must identify the oil type—by industry name—within six hours and, if requested, analyze a sample within 24 hours.

“We are really pleased with the depth the committee went to and the specificity of its recommendations particularly…governing spill response plans,” said Rebecca Craven, program manager at the watchdog group Pipeline Safety Trust.

The National Academies committee had previously published a related report in 2013, responding to a Congressional inquiry, that concluded that dilbit is not more prone to spillage than conventional crudes.