California Code, Streets and Highways Code - SHC § 36715

At the conclusion of the public hearing to establish the district, the city council may adopt, revise, change, reduce, or modify the proposed assessment or the type or types of improvements and activities to be funded with the revenues from the assessments.  Proposed assessments may only be revised by reducing any or all of them.  At the public hearing, the city council may only make changes in, to, or from the boundaries of the proposed district that will exclude territory that will not benefit from the proposed improvements or activities.  Any modifications, revisions, reductions, or changes to the proposed assessment district shall be reflected in the notice and map recorded pursuant to Section 36718.