California Code, Streets and Highways Code - SHC § 8756

In selecting bonds for retirement, the treasurer shallfollow the procedure set forth in Section 8768.  The decision of the treasurer in selecting bonds for retirement shall be conclusive in the absence of fraud.  The treasurer shall make provision for returning to owners releasing unpaid assessments under Part 8 all interest not accrued less the premium and interest paid on the bonds retired and the cost ofadministering retirement of the bonds.