The shale formation has about 84 trillion cubic feet of undiscovered, technically recoverable natural gas, according to the report from the United States Geological Survey. This is drastically lower than the 410 trillion cubic feet that was published earlier this year by the federal Energy Information Administration.

As a result, the Energy Information Administration, which is responsible for quantifying oil and gas supplies, has said it will slash its official estimate for the Marcellus Shale by nearly 80 percent, a move that is likely to generate new questions about how the agency calculates its estimates and why it was so far off in its projections.

The decision by the agency to lower the estimates comes amid growing scrutiny from Congress about how the administration calculates its numbers and why it depends on outside and industry-tied consultants to produce some of its reports.