Economic impacts due to changes in livestock grazing are a function of the amount of forage available and the economic value of the forage. For livestock grazing, long-term surface-disturbing actions from actions listed in Appendix T may affect available animal unit months (AUMs). BLM actions to withdraw certain lands for livestock grazing would also reduce the available forage on federal lands. In addition, land disposal actions may have economic impacts; however, those impacts were not analyzed quantitatively because it is difficult to predict the net change in AUMs. Subsequent landowners may continue to graze the land, leaving overall livestock production and output in the region unaffected.

The economic analysis of livestock grazing impacts is based on a long-term average (from 1988 to 2009) of authorized use as a proportion of active use. Based on data from the BLM’s Rangeland Administration System (RAS), authorized use ranged from 43 percent to 79 percent of active use between 1988 and 2009, with an average value of 64.21 percent (BLM 2010a). Whereas permitted AUMs include active and suspended non-use AUMS, active AUMs exclude suspended non-use AUMs. Authorized use represents AUMs billed for and paid for each year for a permit/lease. These AUMs are not the same as actual use AUMs (and may or may not be reasonably close to actual use AUMs), but are closer to what takes place on the ground each year, or the “actual use”, than the active use AUMs. Authorized use information is obtained from the RAS, while actual use represents the AUMs physically used on the ground. Actual use may be less than or equal to authorized use, but authorized use provides an upper bound for actual use. The BLM adjusts authorized use on an annual basis to account for the forage value of the land in a given year, based on climatic conditions (e.g., drought), as well as taking into account the needs of the land and the ranch operators.

Whereas reductions in land available for livestock grazing (via long-term surface disturbance or grazing withdrawal) are based on active use AUMs, financial conditions on a given ranch operation are determined by actual use (i.e., the actual forage value of the land that is used for livestock) and authorized use (e.g., bank loans that are based on the available forage value of federal leases held by the ranch operator). Thus, authorized use is a more appropriate baseline than active use from which to measure reductions in available AUMs due to surface disturbance or restriction on grazing land. If reductions were measured from a baseline of active use, economic impacts would be overstated (BLM 2010a).

Historical analysis of data from the BLM’s RAS database shows that authorized use in the Cody and Worland Field Offices averaged 64.21 percent of active use from 1988 to 2009 (BLM 2010a). Thus, the economic analysis of livestock grazing impacts uses a baseline of 195,742 AUMs, which represents 64.21 percent of the active use of 305,887 AUMs. Reductions in AUMs due to long-term surface disturbance and grazing restrictions are also adjusted for the ratio of authorized to active use.

Table X-8 provides a summary of initial AUMs and total AUMs lost by 2027 due to surface-disturbing activities. Based on current allocations of AUMs to cattle and sheep, 85 percent of the AUM reduction is allocated to cattle and the remainder is allocated to sheep, for the purpose of estimating changes in output and employment. (There are also some AUMs allocated to horse and buffalo grazing, but these comprise one percent and less than one percent, respectively.) Surface disturbance acres were converted to AUMs using a conversion factor of 10.5 acres per AUM (BLM 2009c).

Due to price fluctuations, average per-AUM values for cattle and sheep are based on the 1998 to 2007 average value of production estimates from the Wyoming Agricultural Statistics Service, adjusted to year 2008 dollars (Taylor 2009; Taylor 2010). The value for cattle is $46.31 per AUM and the value for sheep is $44.83 per AUM (in 2008 dollars). Including indirect and induced impacts, the value of one AUM for cattle is $95.67 and for sheep $104.97 (in 2008 dollars). Table X-9 shows the economic impact assumptions for cattle and sheep. The direct economic impact is the estimated change in livestock output per AUM; IMPLAN generates the indirect and induced impacts.

Table X-10 provides a summary of the employment impacts assumed according to unit changes in livestock AUMs.