Cal. Water Code § 4252

In all cases of rights to divert the direct flow of a stream, without storage, for power development or other nonconsumptive use, where the entire flow so diverted, with the exception of reasonable transportation losses, is returned to the same stream system above the next lower diversion, the owners of these rights shall share on account of these rights only in the equal apportionment of one-tenth of the budget for the service area, and shall not share in so far as these rights are concerned in the apportionment of the remaining nine-tenths.