California Code, Health and Safety Code - HSC § 41512.5

A district board may adopt a schedule of fees applicable to emission sources not included within a permit system adopted pursuant to Section 42300 to cover the estimated reasonable costs of evaluating plans required by law or by district rule or regulation, including, but not limited to, review, inspection, and monitoring related thereto. The fees shall not exceed the estimated costs of reviewing, monitoring, and enforcing the plan for which the fees are charged.

The district board shall hold a public hearing at least 30 days prior to the meeting of the district board at which the adoption or revision of the fee schedule is to be considered, and supporting data on the actual or estimated costs required to provide the service for which the fee is proposed to be charged shall be made available at that public hearing.