Despite recording more than 500 spills, the Wyoming Oil and Gas Conservation Commission levied no fines for unauthorized releases in 2013.

Natural resources program supervisor Tom Kropatsch says that figure includes all releases -- whether of oil, natural gas, produced water or drilling mud.

“In 2010 we actually reduced the volume requirements on reportable spills to us. So, we see a lot more, as far as numbers of spills now than we did several years ago, just because we changed the requirement on volume.”

There were 65 spills that released more than 10 barrels of oil. The largest was in May, when Fossil Creek Resources spilled 360 barrels of crude at their drill site in the Niobrara -- the equivalent of about half a swimming pool worth of oil. But Kropatsch says the size of the spill isn’t always the most important factor.

“You know, obviously the larger spills, they kind of catch your attention a little more than a spill that’s one or two barrels, but potentially even more important than the volume is what did it impact. Especially if it impacted or was near any water or anything like that. Or near a subdivision or a town.”

Kropatsch says so long as operators report spills and take appropriate steps to clean them up, the Commission hasn’t traditionally levied fines. The last time it did was in 2011.