The cooperation or contract may be for any or all of the following purposes:

1. (a) Acquisition or construction of works authorized by this division.
2. (b) A water supply.
3. (c) Acquisition or disposal of water or water rights or water storage or conservation facilities and rights, and any interest in such water, water rights, or water storage or conservation facilities.
4. (d) Acquisition or construction of works for any useful purpose.
5. (e) Investigation, study, or preparation of proposals or plans for any or all of the above purposes.
6. (f) Obligation of the district to repay to the United States advances of funds made by the United States to the district for any or all of the above purposes.
7. (g) Assumption as principal or guarantor of indebtedness to the United States.