The monthly survey Form EIA-860M, “Monthly Update to Annual Electric Generator Report,” supplements the annual survey form EIA-860 data with monthly information that monitors the current status of existing and proposed generating units at electric power plants with 1 megawatt (MW) or greater of combined nameplate capacity.
The EIA estimates the current and near-term unit inventory of electric power generating capacity by integrating the information on these surveys along with ongoing EIA research of new units. However, creating this monthly estimate sometimes requires the use of data submitted on the annual EIA-860 before it has been fully verified by EIA. For this reason, reported capacities are EIA’s preliminary estimates of capacity for that month. Estimates will be corrected without specific acknowledgement or explanation in the subsequent month’s inventory.