Whenever there is in any fund or in cash balances in the state treasury more than sufficient to meet the current expenditures properly payable therefrom, and over and above the amount belonging to the permanent school fund as shown by the separation made by the state treasurer, the state treasurer may invest such portion of such funds or balances over and above that belonging to the permanent school fund in registered warrants of the state of Washington at such times and in such amounts, and may sell them at such times, as he or she deems advisable: PROVIDED, That those funds having statutory authority to make investments are excluded from the provisions of RCW
43.84.120.
Upon such investment being made, the state treasurer shall pay into the appropriate fund the amount so invested, and the warrants so purchased shall be deposited with the state treasurer, who shall collect all interest and principal payments falling due thereon and allocate the same to the proper fund or funds.