16 U.S. Code § 2806 - Contracts and grants
The Secretaries may each carry out any action that such Secretary is responsible for implementing under the Plan through grants to, or contracts with, any person, any other Federal department or agency, any State agency, or any regional commission.
Any contract entered into, or any grant made, under subsection (a) of this section shall contain such terms and conditions as the Secretary concerned shall by regulation prescribe as being necessary or appropriate to protect the interests of the United States. No contract may be entered into, and no grant may be made under subsection (a) of this section, for any purpose that is in violation of any applicable State or local law.
The amount of any grant made under subsection (a) of this section may not exceed an amount equal to one-half the estimated cost of the project for which the grant is made.
Each recipient of a grant or contract under this section shall make available to the Secretary concerned and to the Comptroller General of the United States, for purposes of audit and examination, any book, document, paper, or record that is pertinent to the funds received under such grant or contract.