The reduced output was the first following a four-year upward trend, according to the Ohio Department of Natural Resources in its annual state mining review.
Production from all of the state's mines in 2006 totalled 22.7 million tons last year versus 25.2Mt in 2005, and the total value of mined coal over the same period was $US618 million - a 1.2% drop from the prior year.
However, state and industry experts said there was likely nothing to worry about, as mining by nature can be cyclic.
Ohio Air Quality Development Authority executive Mark Shanahan, a spokesman for the office that oversees the Ohio Coal Development Office, said it could be attributed to delivery contract schedules or other factors.
"My sense is that the future for Ohio coal is still very strong and bright, and we need to look at it over probably a couple of years to see if there's any sort of a trend," he told the Associated Press.
Natural Resources mine permit manager Lanny Erdos added to the news service: "It was really kind of surprising to me. I fully expect over the next two to five years for production to go up."
Topping production for the state last year were Belmont, Monroe, Harrison and Tuscarawas counties, all located in the eastern region of the state. Sixteen counties statewide are home to 74 surface mines and 11 underground operations.
Of the state's underground production, 61.5% was extracted by longwall, with the balance by continuous mining. No conventional mining was utilised last year, it noted, and two of the state's mines reported 1Mt or more of output.
Most coal was extracted from the Pittsburgh 8, followed by Middle Kittanning, Lower Freeport, Meigs Creek and Upper Freeport; approximately 97% of the year's output came from those five seams.
Total employment for last year came in at 2423, of which 1572 were classified as production staff. On average, they each worked 171 days and collected $56,762.
A potential turnaround seems even more feasible given the state's development plans, which includes an underground operation in Meigs County - which could produce 2Mt per annum - and Ohio American Energy's recently commenced surface complex in Jefferson County, Erdos told the AP.
He also said Columbus firm American Municipal Power is planning a 1000-megawatt power facility near the former of the two properties.
Ohio Coal Association president Mike Carey said long waits for new permits may have been to blame for last year's production, which he agreed was not significant.
"It's hard to judge from year to year," he said.
