(a) All rights-of-way granted under this part are limited to the time periods stated in the grant.

(b) For tribal land, we will defer to the tribe's determination that the right-of-way term is reasonable.

(c) For individually owned Indian land, we will review the right-of-way duration to ensure that it is reasonable, given the purpose of the right-of-way. We will generally consider a maximum duration of 20 years to be reasonable for the initial term for rights-of-way for oil and gas purposes and a maximum of 50 years, inclusive of the initial term and any renewals, to be reasonable for rights-of-way for all other purposes. We will consider a duration consistent with use to be reasonable for rights-of-way for conservation easements. We will consider durations different from these guidelines if a different duration would benefit the Indian landowners, is required by another Federal agency, or the tribe has negotiated for a different duration and the right-of-way crosses tribal land.