Cal. Sts. & High. Code § 2107.4

Not more than one-quarter of the funds allocated to a city or county from the Highway Users Tax Account in the Transportation Tax Fund for the construction of streets therein may be used to make principal and interest payments on bonds issued for such construction, if the issuance of such bonds is authorized by a proposition approved by a majority of the votes cast thereon. The term of any such bonds shall not exceed 25 years.