California Code, Health and Safety Code - HSC § 78650

(a) Undertake those investigations, monitoring, surveys, testing, and other information gathering necessary to identify the existence, source, nature, and extent of the hazardous substances involved and the extent of danger to the public health or environment.

(b) Undertake those planning, legal, fiscal, economic, engineering, architectural, and other studies or investigations that are necessary or appropriate to plan and direct response actions, to recover the cost of those actions, and to enforce this part.