California Code, Public Resources Code - PRC § 43604

(a) During the closure and postclosure maintenance period, a solid waste landfill owner or operator shall maintain evidence of financial ability sufficient to pay postclosure maintenance costs, except that the owner or operator may request reimbursement for costs of postclosure maintenance as they are incurred if the remaining amount of funds is at least equal to the remaining postclosure maintenance cost.

(b) Notwithstanding the effective date of this section, owners and operators shall be required to comply with this section on the effective date of those regulations set forth in Part 258 (commencing with Section 258.1) of Title 40 of the Code of Federal Regulations.