The EIA said sales on production from the lands dropped 4% year-on-year, with the decline driven mostly by declines in coal production as well as offshore oil and natural gas production.

Sales of fossil fuels on federal and Indian lands accounted for about 27% of total fossil fuel sales in the nation in 2012.

In FY2012, sales from production on Indian lands of coal, crude oil and lease condensate, natural gas plant liquids and natural gas were between 3% and 6% of that from federal lands totals.

Fossil fuel sales volumes on federal and Indian lands have dropped 15% since FY 2003 because of declines in offshore natural gas production.

To a lesser extent, offshore oil production also played a role.

“However, that decline was outweighed by the 27% increase in fossil fuel production on nonfederal, non-Indian lands from 2003 to 2012, so that total US fossil fuel production increased 11% over that period,” officials said.

Last week, the EIA said Wyoming, the heart of the Powder River Basin region, was not only the top coal producing state in the US last fiscal year, it was also a dominating force of coal sales from federal and Indiana lands.

Annual coal sales from those areas in the state totaled between 458 million and 509 million tons from the 2003 fiscal year to FY2012. The fiscal year begins October 1 each year.

Production from federal and Indian lands in the state were between 356Mt and 411Mt over the same period, or about 76% to 83% of the US total.

Wyoming PRB mines are among the largest in the country. Most of the coal mined in the Wyoming portion of the PRB are located on these lands.

Using these sales as a proxy for production, Wyoming's federal and Indian lands production has been about 82% to 95% of Wyoming's total production over the past decade, the agency said.