The principal activity of a district is that activity for which the greatest amount of time and money is expended. Districts which are principally electric, but which engage also in other activities, must account for the latter in terms of accounts prescribed in other Articles of this Subchapter. The accounts
Revenues from other activities, and
Expenses of other activities
indicate the positions of non-electric revenues and expenses. They may serve as control accounts for prescribed accounts, or may be replaced by them. This policy does not extend to balance sheet accounts. Multi-activity districts need maintain only the balance sheet accounts prescribed for the principal activity.
Cal. Code Regs. Tit. 2, § 1091.13