The Secretary, by cooperative agreements, may arrange with the Department of Agriculture or with such other Federal or State agencies, as the President may deem desirable, for cooperation in the investigations and surveys of projects proposed under the authority of this subchapter; and in connection with any such project which is undertaken the Secretary by such cooperative agreements may arrange for such cooperation in the construction or operation and maintenance of the project as he deems desirable. Any such cooperative agreement with the Department of Agriculture may provide, among other things (1) that the Secretary of Agriculture shall enter into the repayment contracts, required by section 590z–2 of this title and shall handle the collections of repayments and shall take over the other administrative duties connected with the project, after the Secretary of the Interior announces that the project is ready for operation; (2) if such agreement be entered into after construction of the project has been undertaken by the Secretary of the Interior and after he has entered into the repayment contracts required by section 590z–2 of this title, that the Secretary of Agriculture shall take over the collection of repayments and other administrative duties connected with the project; (3) that no water shall be delivered to or for any land or party while the owner of said land or said party is in arrears for more than twelve months in the payment to the United States of money due and payable under a land contract entered into pursuant to section 590z–3(a) of this title; and (4) that any repayment contract with a water user or water users' organization entered into pursuant to section 590z–2 of this title and any land contract with the same water user or organization entered into pursuant to section 590z–3(a) of this title, if said contracts involve the same land, may be combined in a single instrument. The Secretary of Agriculture is authorized to carry out the provision of any such cooperative agreements.