Cal. Wat. Code § 36404
The board may, in its resolution authorizing the issuance of such warrants, provide that the warrants shall be subject to call and redemption prior to maturity, at the option of the district, at such price or prices as may be fixed in the resolution, not exceeding a premium of 6 percent of the par value of the warrants so subject to redemption. The resolution shall fix the method of giving notice of redemption to the holders of warrants to be redeemed and the price or prices at which the warrants shall be subject to redemption. Warrants so subject to call and redemption prior to maturity shall contain a recital to that effect on their face, and no warrant issued under this chapter shall be subject to call or redemption prior to its fixed maturity date unless it contains such recital.
Ca. Water Code § 36404