Notwithstanding any other provision of this article, any public entity authorized to acquire property for a particular use by eminent domain may acquire property to be used in the future for that use by any means (including eminent domain) expressly consented to by its owner.
Source:
Section 1240.240, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=CCP§ionNum=1240.240..