In 1993, Skagit County granted a special use permit, valid for two years, for the construction of a golf course. The project languished in the hands of its first two owners, and by the time the Upper Skagit Indian Tribe bought the project and finally began construction in 2002, the special use permit had been extended three times.
¶2 Habitat Watch, a citizens group comprised of property owners neighboring the proposed golf course site, opposed the project. Habitat Watch was a party in public hearings that were held prior to the issuance of the initial permit and prior to the first permit extension. Although notice and a hearing were provided for the initial permit decision and the first extension, the county mistakenly failed to provide notice or a public hearing for the second and third permit extensions. As a result, Habitat Watch did not learn of the continued existence of the golf course project until construction began in 2002, seven years after the last public hearing on the project.
¶3 Habitat Watch argues that because notice and an opportunity to be heard were not provided with respect to the last two permit extensions, those extensions are void and susceptible to challenge at any time. The county and the tribe concede that the second and third permit extensions were granted without notice or public hearings. They argue, nevertheless, that the extensions are valid under the *401Land Use Petition Act (LUPA), chapter 36.70C RCW, because Habitat Watch failed to appeal the extensions, despite lack of notice, within 21 days of issuance, and because Habitat Watch failed to exhaust available administrative remedies. We hold that Habitat Watch’s challenges are barred by LUPA and affirm the judgments of the trial court.
I. STATEMENT OF THE CASE
¶4 In 1993, the Skagit County hearing examiner granted a special use permit to David Moore for the construction of a golf course. Notice and a public hearing on Moore’s application were properly provided pursuant to former Skagit County Code (SCC) 14.04.150(4) (1993). In the hearing, Habitat Watch raised the concerns of surrounding landowners, including that the golf course would negatively impact water quality and substantially impact local water supplies.
¶5 Despite Habitat Watch’s objections, the special use permit was granted for a two year period to expire June 14, 1995, after which the grant of approval for the golf course would automatically expire. Ex. 104.h (findings of fact, entry of order) (“The project must be started within two (2) years of the date of this order or the Special Use Permit will become void.”); see, e.g., SCC 14.16.900(2)(d), (d)(ii) (“All special uses . . . shall require a development project be commenced for the entire parcel within 2 years of the permit approval.” Failure to meet the deadline results in “automatic permit reversion.”).
¶6 The project did not meet the deadline established by the special use permit. Still interested in the project, Moore requested that the hearing examiner “extend” the permit for two additional years. Pursuant to the Skagit County Code, the same procedures required for the initial grant of a special use permit were required to grant an extension of a permit. Former SCC 14.04.150(3)(f), (4); former SCC 14.04.240(9) (1993). Extensions, like initial permit grants, required the hearing examiner to provide notice and “con*402duct public hearings, prepare a record thereof and enter findings of fact and conclusions based upon those facts.” Former SCC 14.04.240(9)(a). In the words of the county permit office, “ [t]he proper procedures were outlined in former SCC 14.04.150(3)(f)[1] and required the Hearing Examiner to conduct a public hearing before amending [e.g., to extend] a Special Use Permit.” Ex. 203.
f 7 Accordingly, notice was provided and a public hearing was held to consider Moore’s extension request. See Ex. 104.i. Habitat Watch participated in the proceedings and presented the hearing examiner with evidence in opposition to the project. After weighing the evidence presented, the hearing examiner decided to extend the permit two additional years and provided, “[t]he project must be started by June 14, 1997 or the Special Use Permit will become void.” Clerk’s Papers (CP) at 1083. Habitat Watch did not request reconsideration of or appeal this decision as provided for in former SCC 14.04.240(15)-(16).
¶8 Moore subsequently sold the land and golf course project to the Port Gardner Timber Company. Port Gardner failed to meet the project commencement deadline for the extended special use permit and requested that another extension permit be issued. Unlike the initial grant of the permit and first extension, the hearing examiner failed to provide notice of Port Gardner’s extension request and failed to conduct a public hearing. Compare Ex. 104.j (making no mention of notice given in the second extension), with Ex. 104.i (first extension stating “notice having been given to all property owners within 300 feet of said property”). Nevertheless, the hearing examiner granted the request for a new two year special use permit extension, pushing the deadline for commencement of the golf course project to June 14, 1999. No notice of the decision was provided to parties other than Port Gardner.
*403¶9 Anticipating its failure to meet the June 1999 deadline, Port Gardner made an oral request for an additional extension in November 1998. In response to this oral request, the hearing examiner again granted an extension without holding a public hearing or providing notice of the request or of the decision.2 The deadline for commencement was pushed back until June 14, 2002. Id.
¶10 In 2000, the Upper Skagit Indian Tribe purchased the property from Port Gardner and actively pursued the golf course project. The tribe requested and received a letter from Skagit County confirming that the special use permit was valid and would expire on June 14, 2002.
¶11 In May 2002, a Habitat Watch member noticed logging activity near the proposed golf course site. This activity came nearly five years after the last properly granted permit expired and seven years after the last public hearing on the project. By June 5, 2002, Habitat Watch became aware that a golf course project was still proceeding at the site despite the long delay since the last public hearing.
¶12 On June 7, 2002, Habitat Watch submitted a public disclosure request to Skagit County to determine the authority for the golf course project and learned that the project was going forward based on extensions of the 1993 permit originally granted to Moore. The county did not make applicable records available to Habitat Watch until June 24, 2002. Habitat Watch previously believed that Moore’s permit, which was subsequently sold to Port Gardner and then the tribe, had expired in 1997 after the *404first properly granted permit extension had lapsed. The records made available to Habitat Watch through its public disclosure request showed that the permit had been extended two more times, until June 14, 2002. On July 11, 2002, Habitat Watch filed with the county a petition to revoke the special use permit because the project had not timely commenced.
¶13 After the petition for revocation was filed, the county issued a grading permit for the project on July 26, 2002. The grading permit was contingent on the underlying validity of the special use permit extensions challenged in Habitat Watch’s petition for revocation. In response to the county’s issuance of the grading permit, on July 31, 2002, Habitat Watch filed a LUPA petition and a complaint for declaratory and injunctive relief in superior court to challenge both the grading permit and the validity of the last two special use permit extensions.
¶14 On November 7, 2002, the superior court dismissed Habitat Watch’s challenge to the 1997 and 1998 special use permit extensions because the appeal was not filed within 21 days of the issuance of the extensions and for failure to exhaust administrative remedies. As a result, the court declined to address the merits of the appeal because it did not have jurisdiction under LUPA to do so.3 The court stayed the portion of the LUPA challenge related to the grading permits to allow the proceeding on the petition for revocation of the special use permit to conclude.
¶15 The hearing examiner denied Habitat Watch’s petition for revocation on September 30, 2002, and denied reconsideration of that decision on October 8, 2002. The board of county commissioners denied Habitat Watch’s appeal of that decision in a resolution dated December 9, 2002. On December 20, 2002, Habitat Watch filed a supplemental LUPA action appealing the denial of its petition for revocation of the special use permit.
*405¶16 In a summary judgment hearing, the superior court considered together the remaining challenge to the grading permit from the original LUPA action and the new challenge to the denial of the petition for revocation of the special use permit from the supplemental LUPA action. On May 13, 2003, the trial court granted summary judgment against Habitat Watch, ordered that the grading permit was valid, and affirmed the decision denying Habitat Watch’s petition for revocation.4 In contrast to its earlier dismissal on November 7, 2002, the trial court did not find that the challenges to the grading permit or the denial of the petition for revocation were time barred under LUPA. Rather, the trial court reviewed these decisions pursuant to LUPA and found against Habitat Watch as a matter of law.
¶17 We granted Habitat Watch’s petition for direct review.
II. QUESTIONS PRESENTED
A. Were Habitat Watch’s challenges to the 1997 and 1998 extensions to the special use permit time barred under LUPA?
B. Was the grading permit lawfully approved?
C. Was the petition for revocation properly denied?
D. Does RCW 4.84.370, the statute awarding attorney fees and costs to the prevailing party at all levels, violate equal protection?
III. ANALYSIS
¶18 “In reviewing an administrative decision, an appellate court stands in the same position as the superior *406court.” Wenatchee Sportsmen Ass’n v. Chelan County, 141 Wn.2d 169, 176, 4 P.3d 123 (2000). Conclusions of law are reviewed de novo. Id.
A. Challenges to the validity of the 1997 and 1998 extensions
¶19 The trial court dismissed Habitat Watch’s challenges to the validity of the 1997 and 1998 special use permit extensions because the land use petition was not filed within 21 days of the issuance of those extensions and because Habitat Watch did not have standing because of its failure to exhaust administrative remedies.
¶20 Habitat Watch argues that the last two permit extensions are void because the hearing examiner did not provide notice or a public hearing and that LUPA cannot ever bar judicial review of such decisions. The county argues that LUPA does not distinguish between decisions issued with proper notice and decisions issued without proper notice and asserts that, regardless, the 21-day limitation period runs from the date of decision. The tribe focuses its argument for affirming the trial court’s dismissal on the exhaustion of remedies ground. With respect to the debate over whether Habitat Watch’s challenges are time barred under LUPA, the tribe urges the court to adopt an analysis under which, in the absence of proper statutorily or constitutionally required notice, the 21-day period begins to run upon actual or constructive notice of the land use decision.
¶21 LUPA’s stated purpose is “timely judicial review.” RCW 36.70C.010. It establishes a uniform 21-day deadline for appealing the final decisions of local land use authorities and is intended to prevent parties from delaying judicial review at the conclusion of the local administrative process. As we have recently interpreted LUPA in Wenatchee Sportsmen, Chelan County v. Nykreim, 146 Wn.2d 904, 52 P.3d 1 (2002), and Samuel’s Furniture, Inc. v. Department of Ecology, 147 Wn.2d 440, 54 P.3d 1194, 63 P.3d 764 (2002), once a party has had a chance to challenge *407a land use decision and exhaust all appropriate administrative remedies, a land use decision becomes unreviewable by the courts if not appealed to superior court within LUPA’s specified timeline. See, e.g., Wenatchee Sportsmen, 141 Wn.2d at 181 (“Because [LUPA] prevents a court from reviewing a petition that is untimely, approval of the rezone became valid once the opportunity to challenge it passed.”); Nykreim, 146 Wn.2d at 925, 940.
¶22 LUPA embodies the same idea expressed by this court in pre-LUPA decisions — that even illegal decisions must be challenged in a timely, appropriate manner. See Pierce v. King County, 62 Wn.2d 324, 334, 382 P.2d 628 (1963) (holding that even though a county resolution constituted illegal spot zoning and was therefore void ab initio, the applicable limitations period “begins with acquisition of knowledge or with the occurrence of events from which notice ought to be inferred as a matter of law.”). Under LUPA, relief may be granted where “[t]he body or officer that made the land use decision engaged in unlawful procedure or failed to follow a prescribed process” and where “[t]he land use decision is outside the authority or jurisdiction of the body or officer making the decision.” RCW 36.70C.130(l)(a), (e). Thus, defects in land use determinations that could have resulted in decisions that were void ab initio under pre-LUPA cases fall within LUPA, with its express 21-day limitation period. Moreover, the act quite clearly declares legislative intent that chapter 36.70C RCW is to be “the exclusive means of judicial review of land use decisions.” RCW 36.70C.030(1).
¶23 LUPA specifically applies to the particular type of decision at issue here. This court held that a challenge to a special use permit decision made before enactment of LUPA was appropriately brought by way of a petition for writ of certiorari under chapter 7.16 RCW. Dev. Servs. of Am., Inc. v. City of Seattle, 138 Wn.2d 107, 115, 979 P.2d 387 (1999); Sunderland Family Treatment Servs. v. City of Pasco, 127 Wn.2d 782, 788, 903 P.2d 986 (1995). When enacting LUPA, the legislature expressly provided that the *408act “replaces the writ of certiorari for appeal of land use decisions.” RCW 36.70C.030(1). There should be no question that a challenge to a special use permit decision lies within LUPA — even where the decision is allegedly void.
¶24 LUPA’s statute of limitations begins to run on the date a land use decision is issued. RCW 36.70C.040(2)-(4). The statute designates the exact date a land use decision is “issued,” based on whether the decision is written, made by ordinance or resolution, or in some other fashion. RCW 36-.70C.040(4)(a). When a land use decision is written, it is issued either three days after it is mailed or on the date that the local jurisdiction provides notice that the decision is publicly available. Id. The statute does not indicate to whom the decision should be mailed (or other notice provided), and appears to presume that this specification is indicated elsewhere. When a decision is made by ordinance or resolution, the decision is issued on the date the legislative body passes such ordinance or resolution. RCW 36-.70C.040(4)(b). Finally, the statute provides that if neither of the above categories apply, a land use decision is issued on the date it is entered into the public record. RCW 36-.70C.040(4)(c).
¶25 Here, it is not clear from the record or the briefing when the final two permit extensions were issued within the meaning of RCW 36.70C.040(4). There is nothing in the record that shows the extension decisions were mailed to all parties of record, or otherwise made publicly known, or passed by ordinance or resolution. It is also unclear if and when the decisions were “entered” into the public record.5
*409¶26 At the very latest, the written decisions were issued when the county made them available on June 24, 2002, in response to Habitat Watch’s public disclosure request. By the date of the county’s response to Habitat Watch’s public disclosure request, the county had provided “notice that a written decision is publicly available” pursuant to RCW 36.70C.040(4)(a).6 After seeing the permit extensions, but before commencing a LUPA action, Habitat Watch filed a petition for revocation with the county pursuant to former SCC 14.04.150(3)(f). Habitat Watch did not file a LUPA petition directly challenging the permit extensions until August 1, 2002 — well over 21 days after the permit extensions were made available to Habitat Watch on June 24, 2002.7 As such, the petition was time barred under RCW 36.70C.040(2) and the superior court was correct to *410dismiss Habitat Watch’s challenges to the permit extensions.8
B. The grading permit
¶27 Habitat Watch also sought to vacate the grading permit in its LUPA petition. In granting summary judgment to the tribe and the county on the grading permit issue, the trial court found that the grading permit was “granted in accordance with the State Environmental Policy Act [ch. 43.21C RCW] and is therefore valid.” CP at 39.
¶28 Habitat Watch appeals the dismissal of its challenge to the grading permit on the sole ground that it was issued for an impermissible use. Habitat Watch argues that because there was no lawful establishment of golf course use, the approval of the grading permit for golf course construction was precluded. Our decision in Wenatchee Sportsmen precludes consideration of this challenge.
¶29 In Wenatchee Sportsmen, this court held that a petitioner could not collaterally challenge a rezone decision by way of its LUPA petition that challenged a plat approval when the period for challenging the initial rezone decision had already passed. 141 Wn.2d at 181. The rule applied in Wenatchee Sportsmen controls the present issue. In challenging the grading permit, Habitat Watch actually (and exclusively) challenges the validity of the special use permit and its extensions. Because appeal of the special use permit and its extensions are time barred under LUPA, Habitat *411Watch cannot collaterally attack them through its challenge to the grading permit. The trial court correctly found the grading permit was valid.
C. The petition for revocation
¶30 After learning of the last two extensions to the special use permit, Habitat Watch administratively sought revocation of the special use permit pursuant to SCC 14.16.900(2)(b)(iii). Habitat Watch argued that the permit should be revoked because the project was not commenced by the applicable deadline. First, Habitat Watch asserted that the deadline for commencement was never lawfully extended to June 14, 2002, and that rather, assuming the third permit extension was valid, the third permit extension should be interpreted to set a deadline of June 14, 2001.9 Second, Habitat Watch claimed that, regardless of the date when the project had to begin, the project did not in fact commence by the later date of June 14, 2002. The hearing examiner denied the petition to revoke. After Habitat Watch was unsuccessful in its appeal before the board, it supplemented its LUPA petition with appeals of the hearing examiner and board denials.
¶31 The superior court affirmed the administrative decisions to deny Habitat Watch’s petition for revocation, concluding that “[t]he 1997 and 1998 extensions of the special use permit were validly granted,” the project was commenced within the established time limit and was, therefore, valid, and the procedures used to deny Habitat Watch’s petition for revocation were in compliance with county code and state law. CP at 39.
¶32 Despite the inconsistency found in the hearing examiner’s written decision granting the third permit extension (between the text “two (2) additional years,” which would establish a deadline of June 14, 2001, and “until *412June 14, 2002”), the outcome was that condition number 15 of the special use permit was modified to read “[t]he project must be started by June 14, 2002 or the Special Use permit will become void.” Ex. 104.k. To the extent that Habitat Watch challenges the proper deadline established in the modification of the special use permit, it is actually challenging the third permit extension. As previously noted several times, any challenge to the third permit extension is barred by LUPA.
¶33 Assuming the deadline for commencement was June 14, 2002, Habitat Watch argues that the planning and preparation that had taken place to date — including the harvesting of trees and the filing of an application for a grade and fill permit — was insufficient to start the project. However, it fails to adequately support this claim. While Habitat Watch argues the hearing examiner anticipated more than mere planning and design work would be required to start the project, this does not mean that tree harvesting or applying for a grading permit are insufficient. In denying Habitat Watch’s petition for revocation, the hearing examiner found that the tribe had submitted an extensive application for a grading permit, retained a surveyor to work on the property, obtained a forest practice conversion permit, put into place an excavator, chain saws, and logging equipment, and removed trees from the property, all prior to June 14, 2002. CP at 806. Habitat Watch has not challenged these findings of fact. The hearing examiner determined that the project commenced when the tribe applied for the grading permit. Local jurisdictions with expertise in land use decisions are afforded an appropriate level of deference in interpretations of law under LUPA. RCW 36.70C.130. Habitat Watch provides us with no reason to depart from the hearing examiner’s determination that the project had started by June 14, 2002, and we decline to do so.
D. Attorney fees
¶34 As the prevailing parties at all levels of administrative and judicial review, the tribe and the county assert *413they are entitled to attorney fees pursuant to RCW 4.84-.370, which provides in full:
(1) Notwithstanding any other provisions of this chapter, reasonable attorneys’ fees and costs shall be awarded to the prevailing party or substantially prevailing party on appeal before the court of appeals or the supreme court of a decision by a county, city, or town to issue, condition, or deny a development permit involving a site-specific rezone, zoning, plat, conditional use, variance, shoreline permit, building permit, site plan, or similar land use approval or decision. The court shall award and determine the amount of reasonable attorneys’ fees and costs under this section if:
(a) The prevailing party on appeal was the prevailing or substantially prevailing party before the county, city, or town, or in a decision involving a substantial development permit under chapter 90.58 RCW, the prevailing party on appeal was the prevailing party or the substantially prevailing party before the shoreline [s] hearing board; and
(b) The prevailing party on appeal was the prevailing party or substantially prevailing party in all prior judicial proceedings.
(2) In addition to the prevailing party under subsection (1) of this section, the county, city, or town whose decision is on appeal is considered a prevailing party if its decision is upheld at superior court and on appeal.
Under this statute, parties are entitled to attorney fees only if a county, city, or town’s decision is rendered in their favor and at least two courts affirm that decision. The possibility of attorney fees does not arise until a land use decision has been appealed at least twice: before the superior court and before the Court of Appeals and/or the Supreme Court. RCW 4.84.370(1). Thus, parties challenging a land use decision get one opportunity to do so free of the risk of having to pay other parties’ attorney fees and costs if they are unsuccessful before the superior court. See Baker v. Tri-Mountain Res., Inc., 94 Wn. App. 849, 854, 973 P.2d 1078 (1999). Unless we accept Habitat Watch’s argument *414that RCW 4.84.370 is unconstitutional, the county and the tribe are entitled to attorney fees.
¶35 Habitat Watch asks this court to find that RCW 4.84.370 is unconstitutional because it “denies equal protection by discriminating among parties in the exercise of fundamental, First Amendment petitioning rights based not on the merits of their claims but upon whether their positions are aligned with the government.” Reply Br. of Habitat Watch at 33. “A statute is presumed to be constitutional, and the party challenging its constitutionality bears the burden of proving its unconstitutionality beyond a reasonable doubt.” State v. Thorne, 129 Wn.2d 736, 769-70, 921 P.2d 514 (1996).
The right to equal protection guarantees that persons similarly situated with respect to a legitimate purpose of the law receive like treatment. In order to determine whether the equal protection clause has been violated, one of three tests is employed. First, strict scrutiny is applied when a classification affects a fundamental right or a suspect class. Second, intermediate scrutiny is applied when a classification affects both a liberty right and a semi-suspect class not accountable for its status. The third test is rational basis. Under this inquiry, the legislative classification is upheld unless the classification rests on grounds wholly irrelevant to the achievement of legitimate state objectives.
State v. Harner, 153 Wn.2d 228, 235-36, ¶ 12, 103 P.3d 738 (2004) (citing Thorne, 129 Wn.2d at 770-71). We first determine whether RCW 4.84.370 creates a class distinction requiring an equal protection analysis.
¶36 Habitat Watch argues that a “party’s risk of paying attorney fees under RCW 4.84.370 is tethered directly to its success at the administrative level. Accordingly, a private party challenging a government decision will never have been the substantially prevailing party at the administrative level.” Reply Br. of Habitat Watch at 34. The county responds by arguing that RCW 4.84.370 does not create a discernible distinction between classes of litigants. Rather, “the ‘class’ of land use litigants which end[s] up aligned *415with the government is not preordained. It is ever-changing” depending on the local government’s final determination under applicable law. Skagit County’s Sur-Reply Br. at 3.
¶37 Whether a private party is initially aligned with the local government does not determine whether the private party will have prevailed before the county, city, or town, as one or more levels of administrative review may reverse or significantly alter the local government’s initial permit determination. This may be demonstrated by a short example. If a landowner’s permit application is first denied by a land use planner, the landowner can appeal that decision to a hearing examiner, city council, county board, or other administrative body — depending on the administrative review process the county, city, or town has in place. Another private party, although not the permit applicant, might have an interest in the outcome of the permit decision and argue before the reviewing body that the initial permit decision should be affirmed. If the landowner is successful in getting the denial reversed, and that becomes the “land use decision” within the meaning of LUPA (because there is no further opportunity for review within the local government), then the landowner has prevailed before the “county, city, or town” despite the fact that it disagreed with the local government’s initial determination. RCW 36.70C.020(1); RCW 4.84.370(l)(a). This landowner will never be subject to paying attorney fees. The party opposing the permit, on the other hand, might bring a LUPA petition seeking reversal of the local government’s final determination. It will not be considered a prevailing party before the county, city, or town, and might be subject to attorney fees if it appeals the decision to the Court of Appeals and is unsuccessful at each level.
¶38 The situation would be reversed if the land use planner’s decision to deny the permit was affirmed through any and all levels of administrative review. In that case, the landowner would be the land use petitioner and the private party opposing the permit is the prevailing party before the *416local government. The private party would be eligible for attorney fees against the landowner if the landowner continued to appeal the land use decision to the Court of Appeals or higher and was unsuccessful at each level of judicial review. A party’s eligibility for attorney fees is certainly tied to whether that party prevailed before the county, city or town, but because any private party has the opportunity to prevail before the county, city, or town, RCW 4.84.370 does not create a discernible, predetermined classification between private litigants. Therefore, Habitat Watch’s argument that RCW 4.84.370 discriminates between private parties challenging local government decisions and those aligned with local governments fails.
¶39 Although unclear, it appears that Habitat Watch also argues that RCW 4.84.370 distinguishes between private land use litigants and the counties, cities, and towns whose decisions are on appeal. Habitat Watch fails to expand upon this claim, concluding without support that “the government will never be a losing party because it will always prevail before itself at the administrative level. Consequently, the law shifts awards only one way: from a private party to the government and those aligned with the government.” Reply Br. of Habitat Watch at 34. “[T]his court will not review issues for which inadequate argument has been briefed or only passing treatment has been made.” State v. Thomas, 150 Wn.2d 821, 868-69, 83 P.3d 970 (2004) (citing State v. Johnson, 119 Wn.2d 167, 171, 829 P.2d 1082 (1992); State v. Olson, 126 Wn.2d 315, 321, 893 P.2d 629 (1995)). Habitat Watch has failed to adequately brief its conclusion that local governments may never be liable to pay attorney fees and, therefore, we decline to address it.10
¶40 Accordingly, we decline to decide on the briefing we received whether RCW 4.84.370 is unconstitutional.
*417IV. CONCLUSION
¶41 We affirm the judgments of the trial court dismissing Habitat Watch’s LUPA petition and supplemental LUPA petition in their entirety. We award attorney fees and costs under RCW 4.84.370 and in accordance with RAP 18.1.
Alexander, C.J.; C. Johnson, Madsen, Bridge, and Owens, JJ.; and Ireland, J. Pro Tem., concur.