California Code, Public Utilities Code - PUC § 102350

(a) A retail transactions and use tax ordinance may be adopted by the board in accordance with the provisions of Part 1.6 (commencing with Section 7251) of Division 2 of the Revenue and Taxation Code, provided two-thirds of the electors voting on the measure vote to authorize its enactment at a special election called for that purpose by the board, subject to any applicable constitutional requirements.

(b) The board, in the ordinance, shall state the nature of the tax to be imposed, the tax rate or the maximum tax rate, the purposes for which the revenue derived from the tax will be used, and the portion of the area of the board to which the tax would apply, and may set a term during which the tax will be imposed. The purposes for which the tax revenues may be used shall be limited to public transit purposes serving the area of jurisdiction of the district, as determined by the board, including the administration of this part and legal actions related thereto. These purposes include expenditures for planning, environmental reviews, engineering and design costs, and related right-of-way acquisition.

(c) As used in this section, “public transit purposes” includes the public transit responsibilities under the jurisdiction of the district as well as any repair, redesign, or ongoing maintenance of a right-of-way upon which transit is intended to travel, or any bikeway, bicycle path, sidewalk, trail, pedestrian access, or pedestrian accessway.