(a) Payment of expenses by interested parties; work contemplated
The Secretary of Agriculture is authorized, where the public interest justifies, to cooperate with or assist public and private agencies, organizations, institutions, and persons in performing work on land in State, county, municipal, or private ownership, situated within or near a national forest, for which the administering agency, owner, or other interested party deposits in one or more payments a sufficient sum to cover the total estimated cost of the work to be done for the benefit of the depositor, for administration, protection, improvement, reforestation, and such other kinds of work as the Forest Service is authorized to do on lands of the United States: Provided, That the United States shall not be liable to the depositor or land-owner for any damage incident to the performance of such work.

(b) Cooperation where national forests or lands are used by permittees
Cooperation and assistance on the same basis as that authorized in subsection (a) is authorized also in the performance of any such kinds of work in connection with the occupancy or use of the national forests or other lands administered by the Forest Service.

(c) Disposition and availability of moneys; advancements; adjustments
Moneys deposited under this section shall be covered into the Treasury and shall constitute a special fund, which is made available until expended for payment of the cost of work performed by the Forest Service and for refunds to depositors of amounts deposited by them in excess of their share of said cost: Provided, That when deposits are received for a number of similar types of work on adjacent or overlapping areas, or on areas which in the aggregate are determined to cover a single work unit, they may be expended on such combined areas for the purposes for which deposited, in which event refunds to the depositors of the total amount of the excess deposits involved will be made on a proportionate basis: Provided further, That when so provided by written agreement payment for work undertaken pursuant to this section may be made from any Forest Service appropriation available for similar types of work, and reimbursement received from said agencies, organizations, institutions, or persons covering their proportionate share of the cost and the funds received as reimbursement shall be deposited to the credit of the Forest Service appropriation from which initially paid or to appropriations for similar purposes currently available at the time of deposit: Provided further, That when by the terms of a written agreement either party thereto furnishes materials, supplies, equipment, or services for fire emergencies in excess of its proportionate share, adjustment may be made by reimbursement or by replacement in kind of supplies, materials, and equipment consumed or destroyed in excess of the furnishing party's proportionate share.