“The (ExxonMobil spill in Mayflower, Arkansas) appears to be the largest accident involving heavy crude since an Enbridge Energy pipeline spill in 2010 that dumped more than 840,000 gallons near Marshall, Mich., soiling a 39-mile stretch of the Kalamazoo River. Late Tuesday, the federal Pipeline and Hazardous Materials Safety Administration ordered Exxon not to restart the pipeline without getting approval, because of its proximity to populated areas and waterways, and because the initial investigation had not yet uncovered the cause of the spill. The Arkansas spill followed an accident in Utah on March 18 in which a Chevron pipeline leaked more than 25,000 gallons of diesel fuel in a wetlands area about 50 miles from Salt Lake City. “Chevron Pipe Line Company regrets this incident, and we are committed to remediating the affected area and mitigating all impacts on the environment,” Gareth Johnstone, a Chevron spokesman, said in a statement. The Chevron spill was the third in three years in Utah, prompting Gov. Gary R. Herbert to sharply criticize the pipeline agency at a recent news conference. “Obviously, they have not done a very good job of overseeing the pipes that travel between our states,” he said. The safety records of both the Exxon and Chevron pipelines have been under scrutiny in recent years. Last week, the pipeline agency proposed imposing a $1.7 million fine on Exxon Mobil over a 2011 spill that dumped an estimated 63,000 gallons of oil in the Yellowstone River in Montana. Records show that the pipeline agency has proposed a fine of about $150,000 in the same year over the company’s failure to properly test several pipelines. In June 2010, a Chevron pipeline spilled more than 33,000 gallons of crude into Red Butte Creek near Salt Lake City. The company took more than 10 hours to respond to the spill, and it was fined $423,600, according to pipeline agency records. Seven months later, a second Chevron spill sent an additional 21,000 gallons of oil into the same area.”