On November 17, 2017, the pipeline leaked around onto farmland near Amherst, South Dakota. The oil leak is the largest seen from the Keystone pipeline in the state. The leak lasted for several minutes, with no initial reports of damage to water sources or wildlife. Although the spill did not happen on Sioux property, it was in close enough proximity to potentially contaminate the aquifer used for water. The pipeline was immediately shut down, and TransCanada began using the pipe again 12 days after the leak. For much of late 2017, the Keystone pipeline operated at reduced pressure during remediation efforts. The federal Pipeline and Hazardous Materials Safety Administration said that the failure "may have been caused by mechanical damage to the pipeline and coating associated with a weight installed on the pipeline in 2008". Later, the National Transportation Safety Board (NTSB) found that a metal tracked vehicle had run over the area, damaging the pipeline. In April 2018, a federal investigation found that of crude had spilled at the site, almost twice what TransCanada had reported. That number made it the seventh-largest onshore oil spill since 2002.