California Code, Streets and Highways Code - SHC § 1628

The board of supervisors of any county which has established a county highway right of way acquisition revolving fund, may by resolution call an election to obtain authorization for the issuance and sale of bonds to finance the acquisition of rights of way for county highway purposes.  Such bonds may be issued if approved by two-thirds of the electors voting at any regular or special election called for such purpose, and shall be limited in amount to one-half of 1 percent of the current assessed valuation of the county.