(1) When the governing body of a municipal corporation has directed the investment of less than all of its surplus funds which are in the custody of the county treasurer, and thereafter the treasurer, pursuant to § 1, chapter 173, Laws of 1967, invests all such surplus as part of the county's residual treasury cash balance ". . . to the maximum prudent extent . . . in United States government securities . . ." such investment does not affect the individual fund balances of the respective municipal corporations in his custody, and each municipal corporation retains the power to expend or invest its funds according to the respective fund balances shown in its accounts. (2) A proposed accounting regulation of the state auditor requiring county treasurers to account uniformly for their investments made under the provisions of chapter 173, Laws of 1967, as investments of residual cash in the county treasury would be consistent with the provisions and intent of the act. (3) It is the responsibility of the county finance committee, rather than that of the treasurer, to ascertain both the availability of surplus municipal funds for investment under the provisions of chapter 173, Laws of 1967, and the "maximum prudent extent" to which they may be invested, taking into account both the anticipated expenditure and investment requirements of each municipal corporation whose funds are in the custody of the county treasurer.