Cal. Wat. Code § 79220
Notwithstanding any provision of this division or the State General Obligation Bond Law, if the Treasurer sells bonds pursuant to this division that include a bond counsel opinion to the effect that the interest on the bonds is excluded from gross income for federal tax purposes, subject to designated conditions, the Treasurer may maintain separate accounts for the investment of bond proceeds and for the investment earnings on those proceeds. The Treasurer may use or direct the use of those proceeds or earnings to pay any rebate, penalty, or other payment required under federal law or to take any other action with respect to the investment and use of those bond proceeds required or desirable under federal law to maintain the tax-exempt status of those bonds and to obtain any other advantage under federal law on behalf of the funds of that state.
Ca. Water Code § 79220