North Dakota isn't required by state law to disclose oil spills to the public. As it turns out, the state has opted to keep hundreds of pipeline spills quiet over the past two years, according to documents obtained by the Associated Press. The state produces nearly a million barrels of oil daily, second in oil production in the U.S. behind only Texas. 

There were 300 pipeline spills in North Dakota from January 2012 to the present, none of which were made public by officials, according to the AP. Most of those spills were small in size. There's one spill in particular that seems to have grabbed the AP's attention: a massive — 865,000 gallon — oil spill from a Tesoro Logistics pipeline in the state last month, which covered several acres of a nearby farm. That spill raised some substantial questions about the ability of private oil companies to detect and correct infrastructure problems before something bad happens. It turns out that it also took the state 11 days to say anything about the spill, only doing so in response to questions from the press. The spills are just one portion of 750 undisclosed oil field "incidents" since 2012. Of all these incidents, only a road accident involving an oil truck was reported publicly. 

Recent estimates suggest that North Dakota has as much as 7.4 billion barrels of recoverable oil and 6.7 trillion cubic feet of natural gas, indicating that the current oil industry boom in the state has some staying power there. The state's Health Department is currently reviewing its public reporting policies, including the threshold used to determine whether a spill is severe enough to warrant public notification.