several more months to clean the oil out of the marsh where the spill originated. However, a year later, a 35-mile stretch of the river remained closed. Originally estimated at US$5 million, by September 2011, cleanup costs passed $585 million and were expected to rise by 20 percent. The cleanup expense by summer 2012 had totalled $765 million. By November 2014, the total had risen to $1.21 billion, with an estimated $219 million in costs yet to be paid. Aftermath In June, 2012, authorities reopened most of the of the river that had been closed to recreation after the spill. Part of the river at the Morrow Lake delta remained closed and other sections of the river remain restricted because of the ongoing cleanup of the oil sands product called diluted bitumen (dilbit) oil the pipeline had been transporting. The United States Department of Transportation summer 2012 "fined Enbridge $3.7 million dollars and as part of that fine they listed 22 probable violations that happened relating to the spill. And several of those [violations] are about what happened in the [Edmonton] control room". One of the reasons for the vast escalation in time and expense of cleanup was that the EPA had never handled a dilbit spill. In addition, it is reported that Enbridge never informed the EPA of the product distinction. Dilbit, like all crude oil, floats in water but, over time, will sink, complicating cleanup efforts, particularly if dredging is considered too ecologically damaging. Other environmental factors will affect the rate at which this process takes place. This disaster was the largest on-land spill in American history to date. In July 2016, Enbridge agreed to pay $177 million in penalties and improved safety measures in a settlement with the U.S. Justice Department and the Environmental Protection Agency. National Transportation Safety Board investigation In July 2012, the National Transportation Safety Board, the U.S. federal agency with regulatory authority over the failed pipeline, issued a report representing the official conclusion of the investigation into the incident. The investigators found that the operating firm, which had received an automated signal from the pipeline that a breach had occurred, misunderstood or did not believe the signal and attempted to continue to pump dilbit oil through the pipeline for 17 hours after the breach. Local firefighters were notified, and tried to locate the southern Michigan wetland site of the breach, but were initially