(Undated) -- The United States Geological Survey report on the amount of recoverable gas contained in the Marcellus Shale was held up by a now-defunct state law that kept a lid on the natural gas wells being drilled in Pennsylvania. Jim Coleman, with the USGS, was part of the team of geologists trying to figure out how much gas is in the Marcellus Shale. To do it, Coleman says, the geologists needed information about gas well production in the state -- information the state Department of Environmental Protection kept confidential for a period of five years. "(The) Pennsylvania state legislature and the governor agreed that that was no longer a reasonable thing to do so they passed a law and he signed it where they now release the data I think it’s every six months" he says. Once the law to publicize well production was passed in March 2010, the USGS could finish up its assessment. They’re reporting the Marcellus Shale contains some 84 trillion cubic feet of extractable natural gas. Upon the release of that report federal officials announced they would revise their own gas estimate, which reported more than 400 trillion cubic feet. For more information on natural gas drilling in the commonwealth, check out witf's StateImpact Pennsylvania project.