Grazing Improvement Act of 2012

Grazing Improvement Act of 2012 - Amends the Federal Land Policy and Management Act of 1976 (the Act) to double from 10 to 20 years the period of a term for grazing permits and leases for domestic livestock grazing on public lands or lands within national forests in 16 contiguous western states. Permits the issuance of permits and leases for a period shorter than 20 years (under current law, shorter than 10 years), including where the Secretary concerned determines that the initial environmental analysis under the National Environmental Policy Act of 1969 (NEPA) regarding a grazing allotment, permit, or lease has not been completed.

Directs that grazing permits or leases issued by the Secretary of the Interior respecting lands under the jurisdiction of the Department of the Interior and grazing permits issued by the Secretary of Agriculture (USDA) respecting National Forest System lands that expire, are transferred, or are waived after this Act's enactment be renewed or reissued, as appropriate, under the Act, the Granger-Thye Act, the Bankhead-Jones Farm Tenant Act, or the California Desert Protection Act of 1994.

Allows the exclusion of the renewal, reissuance, or transfer of a grazing permit or lease by the Secretary concerned from the NEPA requirement to prepare an environmental analysis if: (1) such decision continues to renew, reissue, or transfer current grazing management of the allotment; (2) monitoring indicates that such management meets objectives contained in the land use and resource management plan of the allotment; or (3) the decision is consistent with the policy of the Department of the Interior or USDA regarding extraordinary circumstances.

Gives the Secretary concerned the sole discretion to determine the priority and timing for completing each required environmental analysis regarding any grazing allotment, permit, or lease based on the environmental significance of such authorization and available funding.

Makes NEPA inapplicable to domestic livestock crossing and trailing authorizations and transfers of grazing preference.