California Code, Government Code - GOV § 29530

(a) If the board of supervisors so agrees by contract with the State Board of Equalization, the board of supervisors shall establish a local transportation fund in the county treasury and shall deposit in the fund all revenues transmitted to the county by the State Board of Equalization under Section 7204 of the Revenue and Taxation Code, which are derived from that portion of the taxes imposed by the county at a rate in excess of 1 percent, and on and after July 1, 2004, until the rate modifications in subdivision (a) of Section 7203.1 of the Revenue and Taxation Code cease to apply, at a rate in excess of three-quarters of 1 percent, pursuant to Part 1.5 (commencing with Section 7200) of Division 2 of that code, less an allocation of the cost of the services of the State Board of Equalization in administering the sales and use tax ordinance related to the rate in excess of 1 percent, and on and after July 1, 2004, until the rate modifications in subdivision (a) of Section 7203.1 of the Revenue and Taxation Code cease to apply, to the rate in excess of three-quarters of 1 percent, and of the Director of Transportation and the Controller in administering the responsibilities assigned to him or her in Chapter 4 (commencing with Section 99200) of Part 11 of Division 10 of the Public Utilities Code.

(b) Any interest or other income earned by investment or otherwise of the local transportation fund shall accrue to and be a part of the fund.