Projected decline is based on a cumulative production of about 10 billion tons, remaining reserves of 21 billion tons and an annual reserve depletion rate of about 0.6 to 1.1 percent over the next century. Reserves are probably overstated because of the high sulfur content of coal, and actual decline rates may be greater than shown. Region is in mature phase of resource life cycle. Coal production from the northern Rocky Mountains region. Region is in early phase of resource life cycle, as is indicated by its rapidy increasing production.
Region is in early phase of resource life cycle.
Coal production, south-central Rocky Mountains. Region is in early phase of resource life cycle.