In the largest leak in the pipeline's history, the Keystone Pipeline released 600,000 gallons of oil into a small creek in Kansas sometime around December 8. While the Environmental Protection Agency (EPA) says that no drinking water has been affected, residents are dealing with strong odors from the spill.

The Keystone actually has a long history of leaks, along with just about every other pipeline in the country. In fact, according to the Pipeline and Hazardous Materials Safety Administration, there are dozens of "significant" oil pipeline spills every year, costing an average of $3 billion annually.

However, where the Keystone stands out is in the worsening severity of its incidents. Since its installation in 2010, the massive 2,600-mile-long pipeline has had nearly two dozen spills. While the majority of those leaks were smaller than 50 barrels, there have been three huge spills in the last five years, with the largest being the most recent.

In fact, this year's incident is the largest pipeline leak in nearly a decade, resulting in more barrels being spilled than in all of 2021's pipeline leaks combined.

Along with the increasing danger posed by these incidents, critics of the Keystone also say that the oil it carries is particularly difficult to clean-up in case of a spill.

"All oil spills are difficult, but tar sands in particular are very toxic and very difficult, so I'm awfully concerned," said the environmental and landowner advocacy group Bold Nebraska's founder, Janet Kleeb.

Landowners from the area near the spill, like Kansas farmer Bill Pannabecker, told reporters that oil sprayed out "the length of a football field" when the pipeline ruptured, blackening nearby fields. Pannabacker's fence line lies about fifteen feet south of where the pipeline burst.

"That's our livelihood out here," Pannabecker told CBS. "Probably an acre, an acre-and-a-half of grasses was totally covered with oil. But that's on a slope so it would run down, and that's when it ran down into the creek."

Following the rupture, the Keystone system was paused, and TC Energy says that workers immediately went to work trying to contain the leak. To prevent the oil from spreading throughout the state's waterways, the EPA says TC Energy built a dam roughly four miles downstream from the leak.

"As always, the health and safety of our onsite staff and personnel, our community neighbors, and mitigating risk to the environment remains our primary focus," TC Energy wrote in a statement. "We recognize this is concerning to the community and commit that we will continue our response until we have fully remediated the site."

TC Energy said]that it hasn't confirmed a timeline for when the Keystone's operations will restart but that it "will only resume service when it is safe to do so, and with the approval of the regulator."

The EPA wrote in its statement that it expects clean-up to at least last into the week of Dec. 12, but the halt in the pipeline's operations could last much longer. Analysts say that Keystone spills in the past have caused outages lasting roughly two weeks, adding that the contamination of a body of water could make this spill may be more difficult to clean up.

The Keystone is used to transport roughly 600,000 barrels per day from Canada to Oklahoma every day, or just under 20% of all Canadian oil imports to the U.S. After TC Energy announced the spill and operations pause on Thursday, the price of oil surged for a time, and a longer pause in operations is expected to cause more price increases.

The agency is advising residents to avoid the creek and to ensure that kids, pets, and livestock don't approach the creek.