concurring in result.
While I concur in the result reached by the majority, I believe that its discussion of grandfathering provisions, particularly the analogy to litigation, is misplaced. The primary case cited by the majority, Northwestern Fin. Group, Inc. v. County of Gaston, concerns a change to an ordinance which explicitly provided that the old version applied to plans submitted before the effective date of the change. *216329 N.C. 180, 405 S.E.2d 138 (1991). The Court in Northwestern notes that the Board found that this explicit provision applied, then focuses on whether Northwestern had waived its application. Id. at 188, 405 S.E.2d at 143. The language quoted in the majority opinion immediately follows this statement:
Having decided that Northwestern is entitled to have its application reviewed under the 1986 ordinance, we must next determine whether Northwestern waived that right by affirmative acts, that is, by abandonment of the first plans through the submission of the other revised plans, or by a failure to act, that is, the passage of time.
Id. Thus, the language discussed by the majority is focused on waiver by affirmative acts, which is not the issue before this Court. In addition, neither party cites a case in which our Courts have approved grandfathering in the absence of an explicit authorization, nor have we found one. I do not believe that creating a process of implicit grandfathering is appropriate here.
The law regarding vesting of a right to proceed under the prior version of an amended ordinance is well-established:
A party’s common law right to develop and/or construct vests when: (1) the party has made, prior to the amendment of a zoning ordinance, expenditures or incurred contractual obligations substantial in amount, incidental to or as part of the acquisition of the building site or the construction or equipment of the proposed building; (2) the obligations and/or expenditures are incurred in good faith; (3) the obligations and/or expenditures were made in reasonable reliance on and after the issuance of a valid building permit, if such permit is required, authorizing the use requested by the party; and (4) the amended ordinance is a detriment to the party. The burden is on the landowner to prove each of the above four elements.
Browning-Ferris Industries v. Guilford County Bd. of Adj., 126 N.C. App. 168, 171-72, 484 S.E.2d 411, 414 (1997) (internal quotation marks and citations omitted).
Here, plaintiffs made expenditures in reliance on the original permit and the May 2003 letter from Storm Water, and thus acted in good faith, satisfying the third of the Browning-Ferris Industries elements. The amended ordinance tightened the floodplain development restrictions to the detriment of plaintiffs, thus satisfying the fourth. *217However, “[p]ermits unlawfully or mistakenly issued do not create a vested right.” Clark Stone Co. v. N.C. Dep’t of Env’t & Natural Res., 164 N.C. App. 24, 40, 594 S.E.2d 832, 842, disc. appeal dismissed, 358 N.C. 731, 603 S.E.2d 878 (2004). Accordingly, defendants cannot prevail under a theory of vested rights.
Nevertheless, Storm Water first issued a permit to plaintiffs on 27 March 2003. In May 2003, Storm Water determined they had issued the permit in error, and sent plaintiffs a letter revoking the permit, but advising that the application could be revised and resubmitted under the 2000 ordinance. Storm Water did not notify defendants about the error issuing the original permit until early May; the amendment was adopted 12 May 2003. Because Storm Water erred in issuing the original permit and did not catch its mistake in time for defendants to make the necessary revisions, Storm Water treated this process as a revision and reissue, rather than as a new submission. Given our deference to an agency’s interpretation of its own ordinance, I conclude that this process was proper, and would affirm on that basis.