In December 1997, the Board of Regents of the University System of Georgia sold 297 acres of real property to the Development Authority of Gordon County. On July 1,1998, appellants, the Georgia Council of Professional Archaeologists and the Society for Georgia Archaeology, filed suit in the Superior Court of Gordon County, contending that the sale was subject to the Georgia Environmental Policy Act (GEPA), OCGA § 12-16-1 et seq., since it involved the sale of more than five acres of state-owned land. See OCGA § 12-16-3 (7). Believing that the Board of Regents had not complied with GEPA, appellants sought a writ of mandamus to compel the Board of Regents to perform its obligations under GEPA and a declaratory judgment that the Board had violated GEPA; that the sale was null and void; that GEPA required state departments and agencies to identify the purchaser’s intended use of property being sold by the department or agency and make an evaluation thereon; and that state departments and agencies could not avoid their GEPA duty by extracting a promise from the purchaser to do a GEPA evaluation after the sale.
The trial court dismissed appellants’ complaint after finding that the sale of 297 acres did not meet the statutory definition of “a *758proposed governmental action which may significantly adversely affect the quality of the environment” and, even if it did, the decision of the responsible government official did not create a cause of action on behalf of the two plaintiff corporations. See OCGA § 12-16-5 (c). The trial court denied the request for declaratory relief, finding that the parties did not face uncertainty since all the conduct had occurred. The trial court declined to exercise its equity power to set aside the deed, finding that the Board of Regents had complied with GEPA, and that appellants had taken no legal action until six months after the sale was completed, though they had been aware of the proposed sale five months before it occurred. The trial court denied the request for mandamus because the responsible government official had not abused his exercised discretion, and the decision to proceed with the proposed governmental action did not create a cause of action in the plaintiffs. Id. This Court granted appellants’ application for discretionary review and posed the following questions:
1. Does OCGA § 12-16-5 (c) bar plaintiffs’ action challenging the decision of the responsible government official that the proposed governmental action at issue was not a “proposed governmental action which may significantly adversely affect the quality of the environment?”
2. If OCGA § 12-16-5 (c) does not bar the action, what remedy is available for plaintiffs to challenge the responsible government official’s determination that a proposed governmental action is not one which may significantly adversely affect the environment’s quality?
3. What standard of review applies to the superior court’s review of the responsible government official’s decision?
4. Applying that standard, was the superior court correct in affirming the decision of the responsible government official?
GEPA requires the “responsible official” of a “government agency” to determine if a “proposed governmental action” is “a proposed governmental action which may significantly adversely affect the quality of the environment.”1 OCGA § 12-16-4. If it is so deter*759mined, the governmental agency responsible for the project must prepare an environmental effects report;2 publish notice in the legal organ of affected counties that the environmental effects report has been prepared; make the report available to the public upon request; and hold a public hearing if, within 30 days of the publication of the notice in the legal organ, the responsible official receives written requests for a hearing from at least 100 Georgia residents. OCGA §§ 12-16-4; 12-16-5. Prior to the sale of the land at issue, the responsible official decided there was no significant adverse environmental impact from the sale of the property. As a result, no environmental effects report was made, no public notice was published, and no public hearings were held. Appellants maintain that, contrary to the determination of the responsible government official, the sale of the land was a “proposed governmental action which may significantly adversely affect the quality of the environment” which required the responsible official to have an environmental effects report prepared and to notify the public.
It is clear that the sale of more than five acres of state-owned land is a “proposed governmental action” under OCGA § 12-16-3 (7) and that, under OCGA § 12-16-3 (5), the Board of Regents is a “government agency” subject to GEPA. Compare Thornton v. Clarke County School District, 270 Ga. 633 (1) (514 SE2d 11) (1999) (a school district is not a “government agency” under GEPA). At issue in this case is the propriety of the responsible official’s decision that the proposed governmental action was not a “proposed governmental action which may significantly adversely affect the quality of the environment.” The initial question we must address is whether appellants’ suit contesting that decision is barred by OCGA § 12-16-5 (c), which states:
The decision of the responsible official to proceed with the proposed governmental action shall not create a cause of action in any person, corporation, association, county, or municipal corporation; provided, however, the actions of the responsible official in the procedure of giving notice by publication of the environmental effects report and notice by publication of the decision made based upon the report and public comments, if any, may be challenged pursuant to . . . the “Georgia Administrative Procedure Act” if the responsible official acts on behalf of a government agency which is subject to that act or by mandamus otherwise; but any such *760challenge must be commenced within 30 days after the date notice of the responsible official’s decision ... is first published in a legal organ of any affected county or counties.
Contained within the subsection is a clear statement that the responsible official’s decision to proceed with the proposed governmental action does not create a cause of action, followed by a limited waiver of sovereign immunity.3 Under GEPA, the responsible official may make the decision “to proceed with the proposed governmental action” at two points: when the official decides that the proposed governmental action is not one which may significantly adversely affect the quality of the environment; and after receipt of the written comments and/or the public hearing that followed the official’s determination that the proposed governmental action may adversely affect the quality of the environment. Under the statute, the responsible official’s decision to proceed with the governmental action because it is not probable to expect a significant adverse impact on the quality of the environment may not serve as the basis of a judicial action against the responsible official or the government agency on behalf of which the responsible official is acting. Where, as here, a statute “is plain and susceptible of but one natural and reasonable construction, the court has no authority to place a different construction upon it, but must construe it according to its terms.” Hollowell v. Jove, 247 Ga. 678, 681 (279 SE2d 430) (1981). Accordingly, we conclude that OCGA § 12-16-5 (c) bars appellants’ lawsuit, and the trial court did not err when it dismissed that portion of appellants’ complaint which sought to challenge the responsible official’s decision to proceed with the project.4
Our holding that OCGA § 12-16-5 (c) bars appellants’ challenge to the responsible official’s decision that the proposed government action is not one from which it is probable to expect a significant adverse impact on the environment is supported by the additional language in OCGA § 12-16-5 (c), which limits the scope of a permissible legal challenge under GEPA and sets out the time period within *761which such a challenge must be filed. The statute authorizes a legal challenge only to the procedure followed by the responsible official in giving the notices required by OCGA §§ 12-16-4 (c) and 12-16-5 (b) after the official has determined that the proposed governmental action may significantly adversely affect the quality of the environment. The period within which the limited class of permitted suit may be filed commences with the publication of notice of the responsible official’s decision following receipt of the public’s written and verbal comments regarding the proposed government action that has been determined by the responsible official to be one which may significantly adversely affect the quality of the environment. Both the action which can form the basis of a permitted lawsuit and the time period within which such a suit must be filed take place well after the responsible official’s decision that forms the basis of appellants’ complaint, leaving us to conclude that the statute shields the responsible official’s initial decision from judicial review.
In light of our determination that OCGA § 12-16-5 (c) bars appellants’ suit, we do not address the remaining questions we posed in granting appellants’ application for discretionary review since they were dependent upon an initial resolution that § 12-16-5 (c) did not bar appellants’ suit.
Judgment affirmed.
All the Justices concur, except Hunstein, J, who dissents.OCGA § 12-16-3 defines the applicable terms as follows:
(1) “A proposed governmental action which may significantly adversely affect the quality of the environment” means a project proposed to be undertaken by a government agency or agencies, for which it is probable to expect a significant adverse impact on the natural environment . . .
(5) “Government agency” means any department, board, bureau, commission, authority, or other agency of the state . . .
(7) “Proposed governmental action” means any proposed land-disturbing activity by a government agency or funded by a grant from a government agency, any proposed sale or exchange of more than five acres of state owned land . . .
(8) “Responsible official” means the official or body in charge of or authorized to act on behalf of a government agency.
An “environmental effects report” is statutorily defined as “a report on a proposed governmental action which may significantly adversely affect the quality of the environment.” OCGA § 12-16-3 (4).
Under the doctrine of sovereign immunity, the State cannot be sued without its consent. The doctrine of sovereign immunity enjoys constitutional status and therefore cannot be abrogated by this Court. State Bd. of Ed. v. Drury, 263 Ga. 429 (1) (437 SE2d 290) (1993). Since the decision to waive sovereign immunity is a voluntary act on the part of the State, the State may prescribe the terms and conditions on which it will consent to be sued, and the manner in which the suit will be conducted. Id.
Assuming without deciding that the declaratory judgment portion of appellants’ complaint is not barred by sovereign immunity, we conclude that the trial court did not err when it declined to issue a declaratory judgment since, the sale of the land having been completed, there was neither an actual nor a justiciable controversy which would authorize entry of a declaratory judgment. OCGA § 9-4-2; Baker v. City of Marietta, 271 Ga. 210 (1) (518 SE2d 879) (1999).