It shall be legal for the state and any of its agencies, departments, instrumentalities, corporations or political subdivisions or any political or public corporation, any bank, trust company, banker, savings bank or institution, any building and loan association, savings and loan association, investment company and any other person carrying on a banking or investment business, any insurance company, insurance association or any other person carrying on an insurance business, and any executor, administrator, curator, trustee or any other fiduciary, to invest money in their custody in any of the securities authorized to be issued pursuant to the provisions of the Flood Control District Act. Such securities shall be authorized security for all public deposits. Nothing contained in this section with regard to legal investments shall be construed as relieving any public body or other person of any duty of exercising reasonable care in selecting securities.