Cal. PROB § 15600

(a) The person named as trustee may accept the trust, or a modification of the trust, by one of the following methods: (1) Signing the trust instrument or the trust instrument as modified, or signing a separate written acceptance. (2) Knowingly exercising powers or performing duties under the trust instrument or the trust instrument as modified, except as provided in subdivision (b). (b) In a case where there is an immediate risk of damage to the trust property, the person named as trustee may act to preserve the trust property without accepting the trust or a modification of the trust, if within a reasonable time after acting the person delivers a written rejection of the trust or the modification of the trust to the settlor or, if the settlor is dead or incompetent, to a beneficiary. This subdivision does not impose a duty on the person named as trustee to act.