California Code, Government Code - GOV § 53154

The expense of an emergency response shall be a charge against the person liable for expenses under this article.  The charge constitutes a debt of that person and is collectible by the public agency incurring those costs in the same manner as in the case of an obligation under a contract, expressed or implied, except that liability for the expenses provided for in this article shall not be insurable and no insurance policy shall provide or pay for the expenses.