In the case of San Francisco Bay, the conservancy may undertake resource enhancement of an area only upon formal request by resolution of a local public agency or the bay commission, except that, with respect to lands within Contra Costa County, such resource enhancement or other action may be undertaken only upon the formal request by resolution of the local public agency having jurisdiction over such lands; provided, however, that a resource enhancement plan has been prepared and approved as provided in Section 31258.5.