Section 31336 Of Article 3. Investments From California Water Code >> Division 12. >> Part 6. >> Chapter 1. >> Article 3.

. 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.