census tract which is described in paragraph (2) and designated as a qualified opportunity zone under this subsection. (2) Population census tract described A population census tract is described in this subparagraph if— (A) the tract— (i) has a population of zero, (ii) was previously used for industrial purposes and is a brownfield industrial site, and (iii) is contiguous, including by water, to a population census tract on at least 1 side that has been designated as a qualified opportunity zone under this section, or (B) the tract was merged, as a result of the 2020 decennial census, into a census tract described in subparagraph (A)(iii) and met all requirements described in subparagraph (A). (3) Designation For purposes of paragraph (1), a population census tract that is described in paragraph (2) is designated as a qualified opportunity zone if— (A) not later than 30 days after the date of the enactment of this subsection, the chief executive officer of the State in which the tract is located— (i) nominates the tract for designation as a qualified opportunity zone, and (ii) notifies the Secretary in writing of such nomination, and (B) not later than 30 days after receiving the notification under subparagraph (A)(ii), the Secretary certifies such nomination and designates such tract as a qualified opportunity zone. (4) Determination of census tract information For purposes of this subsection, the boundaries and population of a census tract shall be determined based on United States Census Bureau data for the 2010 decennial census. (5) Number of designations Population census tracts designated as a qualified opportunity zone under this subsection shall not be taken into account for purposes of subsection (d). (6) Definitions For purposes of this subsection— (A) Brownfield industrial site The term brownfield industrial site means a population census tract that includes real property the expansion, redevelopment, or reuse of which may be complicated by the presence or potential presence of a hazardous substance