Cal. Gov. Code § 67071
In formulating and maintaining the regional plan, the agency shall take account of and shall seek to harmonize the needs of the region as a whole, the plans of the counties and cities within the region, the plans and planning activities of the state, federal and other public agencies and nongovernmental agencies and organizations which affect or are concerned with planning and development within the region. Where necessary for the realization of the regional plan, the agency may engage in collaborative planning with local governmental jurisdictions located outside the region, but contiguous to its boundaries. In formulating and implementing the regional plan, the agency shall seek the cooperation and consider the recommendations of counties and cities and other agencies of local government, of state and federal agencies, of educational institutions and research organizations, whether public or private, and of civic groups and private individuals.
Ca. Gov. Code § 67071