Colo. Rev. Stat. § 36-4-108
In case of such procedure under the laws of the United States and in the event that any departmental or other officer, agent, or employee of the United States shall, in the judgment of the board, fail or refuse to act or decide within a reasonable time, or in bad faith, or for mere purpose of delay, or act or decide adversely to the legal, constitutional, or inherent rights of the state, upon any question involved and subject to his action or decision or shall obstruct, hinder, or interfere with the necessary occupancy or possession of the lands involved by the state, or any of its agents or employees, the board shall at once proceed to acquire the desired rights or easements, occupancy, or possession by invoking the power of eminent domain of the state. Such proceedings, including the right to enter upon the lands involved for the purpose of examination and survey, and the right of possession during the pendency of the action, and in all other respects, shall be as provided in articles 1 to 7 of title 38, C.R.S., in relation to eminent domain insofar as applicable and as supplemented and enlarged by sections 36-4-104 to 36-4-112.
C.R.S. § 36-4-108
For additional provisions concerning condemnation of public lands belonging to the United States, see article 3 of title 38.