A district may invest such surplus money, as its board deems wise or expedient in any of the following:
- (a) Bonds issued by the district.
- (b) Bonds issued by any school district any part of which is in a county containing any part of the county water district.
- (c) Bonds issued by the State.
- (d) Bonds issued by the United States.
- (e) Registered warrants issued by the State.