Idaho Code § 70-1711
The port commission shall have the authority to direct the port treasurer to invest the moneys in any sinking funds or any capital acquisition or improvement funds of the district, as well as any other funds which the commission shall determine to be in excess of its current cash requirements, for the operation and maintanance [maintenance] of the district, in negotiable, general obligation bonds or other evidence of indebtedness of the United States or of this state or any municipal corporation or political subdivision thereof, or in time certificates of deposit from any banking institution of this state, chartered under the laws of the United States of America or of this state, or as provided in section 70-1802 [, Idaho Code]. Such investments shall be in lieu of depositing said moneys in the designated depositories as provided by the public depository law. The port treasurer shall likewise reduce such bonds, evidence of indebtedness or certificates of deposit to cash, or substitute other of such securities therefor, as when said port commission may direct.
Idaho Code § 70-1711