25 CFR § 166.807
When will we impound unauthorized livestock or other property?
February 24, 2021
We will impound unauthorized livestock or other property under the following conditions:
(a) Where there is imminent danger of severe injury to growing or harvestable crop or destruction of the range forage.
(b) When the known owner or the owner's representative of the unauthorized livestock or other property refuses to accept delivery of a written notice of trespass and the unauthorized livestock or other property are not removed within the period prescribed in the written notice.
(c) Any time after five days of providing notice of impoundment if you failed to correct the trespass.