25 C.F.R. § 169.415
How will BIA conduct compliance and enforcement when there is a life estate on the tract?
(a) We may monitor the use of the land, as appropriate, and will enforce the terms of the right-of-way on behalf of the owners of the remainder interests, but will not be responsible for enforcing the right-of-way on behalf of the life tenant.
(b) The life tenant may not cause or allow permanent injury to the land.