25 U.S. Code § 3115 - Cooperative agreement between Department of the Interior and Indian tribes

(a) Cooperative agreements
(1) To facilitate the administration of the programs and activities of the Department of the Interior, the Secretary is authorized to negotiate and enter into cooperative agreements with Indian tribes to—
engage in cooperative manpower and job training and development programs,
to develop and publish cooperative environmental education and natural resource planning materials, and
to perform land and facility improvements, including forestry and other natural resources protection, fire protection, reforestation, timber stand improvement, debris removal, and other activities related to land and natural resource management.
The Secretary may enter into such agreements when the Secretary determines the public interest will be benefited.
In such cooperative agreements, the Secretary is authorized to advance or reimburse funds to contractors from any appropriated funds available for similar kinds of work or by furnishing or sharing materials, supplies, facilities or equipment without regard to the provisions of section 3324, title 31, relating to the advance of public moneys.
(b) Supervision

In any agreement authorized by this section, Indian tribes and their employees may perform cooperative work under the supervision of the Department of the Interior in emergencies or otherwise as mutually agreed to, but shall not be deemed to be Federal employees other than for purposes of section [1] 2671 through 2680 of title 28 and section [1] 8101 through 8193 of title 5.

(c) Savings provision

Nothing in this chapter shall be construed to limit the authority of the Secretary to enter into cooperative agreements otherwise authorized by law.