¶1 Alpine Lakes Protection Society and several other conservation organizations (collectively, ALPS) appeal two administrative actions, one by the Washington Department of Ecology (Ecology) and the other by the Washington Forest Practices Board (Forest Practices Board). We have linked these two appeals.
¶2 In the first case, ALPS appeals Ecology’s rule-making amendment of WAC 197-11-800.1 This amendment (1) removed classes I, II, and III forest practices permits from its list of government actions that are categorically exempt from the State Environmental Policy Act (SEPA), chapter 43.21C RCW,2 and (2) thereby caused classes I, II, and III *380forest practices permits to be no longer subject to Ecology’s “Rule 305,” WAC 197-ll-305(l)(b)(ii).3 ALPS argues that (1) Ecology was not required to amend WAC 197-11-800 in this manner because SEPA independently authorizes Ecology to apply Rule 305-type “cumulative effects”4 scrutiny to forest practices permits and (2) therefore, Ecology’s amendment of *381WAC 197-11-800 improperly excluded classes I, II, and III forest practices from SEPA review of cumulative effects that a forest-practices permit application might create when considered together with other related, though segmented, forest practices permits.
*379The proposed actions contained in Part Nine[*] are categorically exempt from threshold determination and EIS [environmental impact statement] requirements, subject to the rules and limitations on categorical exemptions contained in WAC 197-11-305.
Note: The statutory exemptions contained in chapter 43.21C RCW are not included in Part Nine. Chapter 43.21C RCW should be reviewed in determining whether a proposed action not listed as categorically exempt in Part Nine is exempt by statute from threshold determination and EIS requirements.
*381¶3 In the second case, ALPS appeals the Forest Practices Board’s denial of its petition for rule making: ALPS petitioned the Forest Practices Board to promulgate a “catchall” provision in its class IV forest practices classification,5 to operate like Ecology’s Rule 305, which would subject otherwise exempt, related, segmented proposals to SEPA review for potential, cumulative environmental impacts. ALPS argues that the Forest Practices Board has a statutory duty to promulgate such a provision and that the Forest Practices Board acted outside its statutory authority in failing to do so.
¶4 We hold that (1) Ecology did not act improperly in amending WAC 197-11-800 and (2) the Forest Practices Board did not act improperly in denying ALPS’ petition to add a “Rule 305-like” catch-all provision to its class IV forest practices classification. We affirm.
FACTS
I. Background
A. Plum Creek’s Forest Practices Permit
¶5 Plum Creek Timber Company owns several thousand acres of land in King and Pierce Counties. Between 1994 and 2001, Plum Creek obtained 25 Department of Natural Resources (DNR) forest practices permits for timber harvest and 3 permits for road construction in the Carbon River Valley and its surrounding hillside near Mount Rainier National Park. DNR determined that all of these permits were for class III forest practices,6 which *382were thereby exempt from environmental review under SEPA.
¶6 At issue here is a class III forest practices permit encompassing a 28-acre piece of Plum Creek land called “Doggone Harvest.” In response to environmental concerns raised by the Mountaineers and two individuals (collectively, the Mountaineers), Plum Creek voluntarily revised its permit application to incorporate aesthetic changes. DNR approved Plum Creek’s application and granted a class III forest practices permit.
B. Ecology’s Rule Making
¶7 Effective September 1, 2003, Ecology amended WAC 197-11-800 to remove classes I, II, and III forest practices permits from its list of SEPA-exempt government actions. This amendment caused these three classes of forest practices permits no longer to be subject to Ecology’s Rule 305, which otherwise could have required SEPA review of “a segment of a proposal” that includes “a series of exempt actions that are physically or functionally related to each other, and that together may have a probable significant adverse environmental impact.” WAC 197-ll-305(l)(b)(ii).
C. ALPS’ Petition for Forest Practices Board Rule Making
¶8 On February 13, 2003, ALPS petitioned the Forest Practices Board to amend its forest practices classification system to ensure SEPA review of related, though segmented,7 forest-practices applications with potentially substantial, cumulative, environmental effects.8 More specifically, ALPS petitioned the Forest Practices Board to promulgate a catch-all provision in its class IV forest practices classification that would operate like Ecology’s Rule 305. ALPS argued that the Forest Practices Board has *383a statutory duty under SEPA and the Forest Practices Act of 1974, chapter 76.09 RCW, to adopt forest practice rules that function similarly to Ecology’s Rule 305 (WAC 197-11-305).
¶9 The Forest Practices Board received written and oral comments on ALPS’ rule-making petition. On March 19, 2003, the Forest Practices Board unanimously denied ALPS’ petition. By letter, dated April 10, 2003, the Forest Practices Board summarized its ruling, which included the following rationale:
A. Contrary to the petition, the Board has no statutory or other legal “duty” to engage in rule making to adopt a rule similar to or that operates like the “305 Rule” described in the petition.
E. As directed by the legislature, the Board has established a short, specific “closed list” of forest practices classed as TV-Special, and thus subject to SEPA analysis on an individual basis. Petitioner’s desire for a “catch-all” or open-ended rule would not be consistent with legislative direction.
Forest Practices Board Admin. R. at 4949.
II. Appeals
A. Administrative
1. Forest Practices Appeals Board
¶10 The Mountaineers appealed the Doggone Harvest class III forest practices permit to the Forest Practices Appeals Board (Appeals Board).9 The Appeals Board conducted hearings to consider whether the Doggone Harvest permit was a “segment of a proposal” triggering SEPA review under WAC 197-11-305 (Rule 305). In its March 21, 2002 written decision, the Appeals Board first determined that the forest practices exemption under SEPA, former *384WAC 197-ll-800(25)(a) (1997), was potentially subject to SEPAreview through WAC 197-11-305. If applicable, Ecology’s administrative Rule 305 would function as an exception to the general rule that categorically exempt activities are not subject to SEPA review.10
¶11 The Appeals Board next determined, however, that Plum Creek’s Doggone Harvest permit was not operationally linked to past, present, or future forest practices and, therefore, Rule 305 would not apply. The Appeals Board denied the Mountaineers’ appeal and affirmed the Doggone Harvest class III forest practices permit.
2. Department of Ecology
¶12 In response to the Appeals Board’s ruling, Plum Creek sought judicial review of WAC 197-11-305 and WAC 197-11-800. Plum Creek argued that Ecology had acted beyond the scope of its legislatively-granted power when it adopted these two rules. Agreeing with Plum Creek, on August 1, 2003, Ecology settled the case by removing forest practices permits from its list of government actions exempt from SEPA review under WAC 197-11-800.
B. Thurston County Superior Court
1. Ecology’s amendment to WAC 197-11-800
¶13 On August 23, 2003, ALPS sought judicial review of Ecology’s rule-making amendment to WAC 197-11-800, which removed class I, II, and III forest practices from its list of SEPA-exempt actions. ALPS argued that Ecology’s rule making (1) was arbitrary and capricious because Ecology misinterpreted SEPA and the amendment conflicted with case law and (2) violated SEPA because this amendment would lead to significant adverse environmental im*385pacts, thus requiring an environmental impact statement (EIS), which was not conducted here.
¶14 On July 23, 2004, the superior court dismissed ALPS’ petition for judicial review. The court ruled that (1) the Forest Practices Board has sole authority to decide which forest practices are subject to SEPA review; (2) Ecology lacks authority to include class I, II, and III forest practices permits under WAC 197-11-800 because these forest practices are statutorily exempt from SEPA under chapter 43.21C RCW and, therefore, not subject to WAC 197-11-305; and (3) Ecology’s amendment to WAC 197-11--800, to remove these three classes of forest practices, did not require an EIS because Ecology was merely making its rules consistent with SEPA.
2. Forest Practices Board’s denial of ALPS’ request for rule making
¶15 ALPS also filed a petition for judicial review, under the Administrative Procedure Act (APA),11 of the Forest Practices Board’s denial of ALPS’ petition for rule making. In this petition, ALPS asked the Forest Practices Board to promulgate forest practice rules that would function similarly to Rule 305’s provision for SEPA review of categorically exempt segmented, but related, proposals that might negatively impact the environment when considered together. See WAC 197-11-305(1).
¶16 The superior court issued a memorandum opinion denying ALPS’ petition. The court ruled that (1) Rule 305 does not apply to class I, II, and III forest practices and (2) the Forest Practices Board’s denial of ALPS’ rule-making petition was not arbitrary and capricious.
C. Court of Appeals
¶17 ALPS appealed both actions, asking us (1) to declare a class IV-special catch-all provision consistent with the *386legislature’s direction to the Forest Practices Board and (2) to hold that the Forest Practices Board must amend the class IV-special list to ensure SEPA review for segmented forest practices having potentially substantial cumulative effects. We linked these two appeals for oral argument and decision.
ANALYSIS
I. Background
A. State Environmental Policy Act
¶18 SEPA requires government agencies to evaluate their actions’ impact on the environment. RCW 43.21C.010 through .031. If a major action will probably have a significant adverse impact on the environment, SEPA requires government agencies to prepare an EIS describing adverse impacts, alternative actions, and other pertinent matters. RCW 43.21C.030, .031; Dioxin/Organochlorine Ctr. v. Pollution Control Hearings Bd., 131 Wn.2d 345, 352, 932 P.2d 158 (1997). Not all actions, however, require an EIS.
¶19 SEPA lists several government actions that are exempt from environmental review.12 But this list is not exhaustive. The legislature directed Ecology to determine other categories of government actions that do not substantially affect the environment. If a proposed action is on Ecology’s nonenvironment-affecting list, an EIS is not generally required. See RCW 43.21C.031,13 .110; see also Dioxin, 131 Wn.2d at 365.
*387¶20 SEPA also requires Ecology to promulgate a rule-based exception to otherwise SEPA-exempt government actions. RCW 43.21C.110(l)(a). In response to this legislative directive, Ecology promulgated two administrative rules, only one of which is at issue here: WAC 197-11-305.14 This rule, also called Rule 305, serves as an exception to Ecology’s list of government actions that are otherwise exempt under WAC 197-11-800.15 Snohomish County v. State, 69 Wn. App. 655, 668, 850 P.2d 546 (1993), review denied, 123 Wn.2d 1003 (1994).
¶21 These linked appeals address the scope of Ecology’s authority under RCW 43.21C. 110(1): first, does RCW 43.21C.110(1) allow Ecology to apply its “cumulative effects” Rule 305 to both administrative and statutory SEPA exemptions? Second, is the forest practices exemption, RCW 43.21C.037, subject to Ecology’s administrative rules promulgated under RCW 43.21C.110(l)(a)? These are issues of first impression.
B. Forest Practices Act
¶22 “The Forest Practices Act is a statewide system of laws designed to manage and protect the State’s natural resources and to ensure a viable commercial timber industry.” Johnson Forestry Contracting, Inc. v. Dep’t of Natural Res., 131 Wn. App. 13, 23, 126 P.3d 45 (2005); see also RCW *38876.09.010(1). Forest practices are “any activity conducted on or directly pertaining to forest land and relating to growing, harvesting, or processing timber.” RCW 76.09-.020(11). The Forest Practices Board is responsible for adopting all forest practice rules,16 which DNR then enforces and administers. RCW 76.09.040(1).
¶23 The legislature created four classes of forest practices based on their potential for damaging public resources. RCW 76.09.050(1). Class I forest practices “have no direct potential for damaging a public resource.” Id. Class II forest practices “have a less than ordinary potential for damaging a public resource.” Id. Class III forest practices are practices “other than those contained in Class I, II, or IV.” Id. Class IV forest practices “have a potential for a substantial impact on the environment” and require DNR to evaluate whether an EIS must be prepared under SEPA. Id. In contrast, classes I through III “are exempt from the requirements for preparation of a detailed statement under [SEPA].” Id.
¶24 Exercising its Forest Practices Act authority, the Forest Practices Board has promulgated rules establishing what forest practices comprise each class. See WAC 222-16--050. The Forest Practices Board has also created a closed list17 of specific forest practices, entitled “Class IV-special,” which automatically require SEPA review. WAC 222-16--050(1).18
*389II. Standard of Review
A. Administrative Procedure Act
¶25 In reviewing an administrative action, we sit in the same position as the trial court and apply the APA standards directly to the agency’s administrative record.19 Under the APA, the “burden of demonstrating the invalidity of agency action is on the party asserting invalidity.” RCW 34.05.570(l)(a).
¶26 RCW 34.05.570 sets forth nine grounds on which a party may challenge an agency’s actions,20 two of which pertain here. First, RCW 34.05.570(2)(c), applicable to Ecology actions, provides in pertinent part: “In a proceeding involving review of a rule, the court shall declare the rule invalid only if it finds that. . . the rule exceeds the statutory authority of the agency ... or the rule is arbitrary and capricious.” Second, RCW 34.05.570(4) (other agency action), applicable to rule-making petitions to the Forest Practices Board, provides for (1) a challenge to “an agency’s failure to perform a duty that is required by law” that violates a party’s rights, RCW 34.05.570(4)(b), and (2) relief only if the agency’s action was “[arbitrary or capricious” or “[o]utside the statutory authority of the agency or the authority conferred by a provision of law.” RCW 34.05-.570(4)(c)(iii), (ii).
¶27 Like the trial court, we review such “questions of law de novo, but we accord substantial weight to the agency’s interpretation of the statutes it administers.” Superior Asphalt & Concrete Co. v. Dep’t of Labor & Indus., 112 Wn. App. 291, 296, 49 P.3d 135 (2002), review denied, 149 Wn.2d 1003 (2003).
*390B. Statutory Construction
¶28 When interpreting statutes, a court’s primary objectives are to ascertain and to carry out the legislature’s intent and purpose. Courts must look first to the statute’s language. If the statute is unambiguous, its meaning derives from the plain language of the statute alone. See Fraternal Order of Eagles, Tenino Aerie No. 564 v. Grand Aerie of Fraternal Order of Eagles, 148 Wn.2d 224, 242, 59 P.3d 655 (2002), cert. denied, 538 U.S. 1057 (2003).
¶29 Courts must also construe a legislative act as a whole. Whenever possible, a court should harmonize the provisions of an act to insure its proper construction. Nisqually Delta Ass’n v. City of DuPont, 103 Wn.2d 720, 730, 696 P.2d 1222 (1985).
III. Ecology’s Rule-Making Authority
A. Scope of RCW 43.21C.110 — Exceptions to Categorical Exemptions
¶30 ALPS argues that RCW 43.21C.110(l)(a) authorizes Ecology to create and to apply a cumulative effects exception rule, WAC 197-11-305, to both administrative and statutory SEPA exemptions because the statute does not distinguish between them. We disagree.
1. Ecology’s administratively-created, categorical, SEPA-review exemptions
¶31 RCW 43.21C.110(1) provides in pertinent part:
It shall be the duty and function of the department of ecology: (1) To adopt and amend thereafter rules of interpretation and implementation of this chapter, subject to the requirements of chapter 34.05 RCW, for the purpose of providing uniform rules and guidelines to all branches of government including state agencies, political subdivisions, public and municipal corporations, and counties. The proposed rules shall be subject to full public hearings requirements ... and the *391department shall have the authority and responsibility for full and appropriate independent promulgation and adoption of rules, assuring consistency with this chapter as amended and with the preservation of protections afforded by this chapter. The rule-making powers authorized in this section shall include, but shall not be limited to, the following phases of interpretation and implementation of this chapter:
(a) Categories of governmental actions which are not to be considered as potential major actions significantly affecting the quality of the environment, including categories pertaining to applications for water right permits pursuant to chapters 90.03 and 90.44 RCW. The types of actions included as categorical exemptions in the rules shall be limited to those types which are not major actions significantly affecting the quality of the environment. The rules shall provide for certain circumstances where actions which potentially are categorically exempt require environmental review. An action that is categorically exempt under the rules adopted by the department may not be conditioned or denied under this chapter.
RCW 43.21C.110(l)(a) (emphasis added). The plain language of this statute directs Ecology: (1) to develop its own list of government-action categories that are not major actions affecting the quality of the environment (“administratively-created” categorical exemptions) and (2) to create a rule-based exception that governs when a proposal potentially falling under an otherwise exempt government-action category may nonetheless require environmental review. Id.
2. Statutorily-created, categorical, SEPA-review exemptions
¶32 In contrast, no language in RCW 43.21C.110(l)(a) mentions a similar exception to any legislatively-created statutory categorical exemption. Rather, the RCW 43.21C-.110(l)(a) exception expressly refers only to categorical exemptions specified by Ecology. Read as a whole, RCW 43-.21C.110(l)(a) not only recognizes administrative categorical exemptions, but it also limits Ecology’s promulgation of *392its exception rule to Ecology-designated (and, therefore, administrative) categorical exemptions. Nisqually Delta Ass’n, 103 Wn.2d at 730. Moreover, RCW 43.21C.229(2) expressly references Ecology’s adoption, under RCW 43.21C.110(l)(a), of exceptions to the use of Ecology-adopted categorical exemptions, again, with no reference to statutory categorical exemptions.
¶33 Thus, by negative inference, this RCW 43.21C-,110(l)(a) limitation precludes application of Ecology’s exception rule to statutory categorical exemptions.
3. SEPA’s infill-development exemption — RCW 43.21C.229
¶34 Citing SEPA’s infill-development exemption under RCW 43.21C.229, ALPS argues that the legislature intended RCW 43.21C.110(l)(a) to apply to both statutorily- and administratively-created categorical exemptions. Again, we disagree.
¶35 Similar to the way in which RCW 43.21C.110(l)(a) directs Ecology to create (administrative) categorical SEPA exemptions, RCW 43.21C.229 directs cities and counties to create their own lists of government actions that are categorically exempt from SEPA review, even if they differ from Ecology’s categorical exemptions:
In order to accommodate infill development and thereby realize the goals and policies of comprehensive plans adopted according to chapter 36.70A RCW, a city or county planning under RCW 36.70A.040 is authorized by this section to establish categorical exemptions from the requirements of this chapter. An exemption adopted under this section applies even if it differs from the categorical exemptions adopted by rule of the department [of ecology] under RCW 43.21C.110(l)(a). An exemption may be adopted by a city or county under this section if it meets the following criteria ....
RCW 43.21C.229(1) (emphasis added).
¶36 Nonetheless, as it did with Ecology, the legislature similarly limited cities’ and counties’ exemption-creating *393authority by making city- and county-created exemptions subject to Ecology’s RCW 43.21C.110(l)(a)’s exception rule:
Any categorical exemption adopted by a city or county under this section shall be subject to the rules of the department [of ecology] adopted according to RCW 43.21C.110(l)(a) that provide exceptions to the use of categorical exemptions adopted by the department.
RCW 43.21C.229(2)21 (emphasis added). Consistent with the plain language of RCW 43.21C.110(l)(a), the plain language of RCW 43.21C.229 recognizes that Ecology’s exceptions, adopted following RCW 43.21C.110(l)(a)’s directive, are limited to Ecology’s SEPA-exemption categories,22 unless otherwise specified by statute. See, e.g., RCW 43.21C.0384(l)(c) (personal wireless services facilities). Similarly specifying otherwise by statute, RCW 43.21C.229 expressly subjects city and county exemptions to Ecology’s RCW 43.21C.110(l)(a)-adopted exceptions.
4. WAC 197-11-305 — inapplicable to statutory exemptions
¶37 ALPS further contends that: (1) RCW 43.21C-.110(l)(a) specifically provides Ecology’s rule-making powers are not limited to those powers this statute outlines and (2) thus, Ecology had power to apply WAC 197-11-305 to statutory exemptions, independent of subsection (a) of RCW 43.21C.110(1).23 This argument also fails.
*394 f 38 Although Ecology may have broad rule-making authority, it cannot implement a rule that conflicts with a clear statutory provision. See Dep’t of Ecology v. Campbell & Gwinn, L.L.C., 146 Wn.2d 1, 19, 43 P.3d 4 (2002) (an agency cannot amend or change a statute through administrative rule making). See also King County Water Dist. No. 68 v. Tax Comm’n, 58 Wn.2d 282, 286, 362 P.2d 244 (1961) (specific term modifies or restricts general terms).24 Nor can an agency act outside its legislatively-delegated authority. And, as we have previously explained, Ecology had legislatively-delegated power under RCW 43.21C-.110(l)(a) only to promulgate exceptions for its otherwise administratively exempt categories.
¶39 Accordingly, we hold that (1) RCW 43.21C-.110(l)(a) authorizes Ecology to create a cumulative effects exception for only those categorical exemptions that Ecology administratively determines meet the standard set forth under this statute and (2) RCW 43.21C.110 does not authorize Ecology to apply Rule 305 to statutory exemp*395tions. Absent legislative authorization, Ecology cannot act in the manner that ALPS urges.
B. RCW 43.21C.037 (Forest Practices Exemption)
¶40 ALPS next argues that: (1) the forest practices exemption, RCW 43.21C.037, is a hybrid (administrative-statutory) exemption, subject to Ecology’s authority under RCW 43.21C.110(l)(a); (2) the Forest Practices Board, not the statute, defines which actions are SEPA exempt; and (3) Ecology has the authority and the duty to guide the Forest Practices Board in determining such administrative-statutory exemptions. Again, we disagree.
¶41 ALPS correctly notes that SEPA does not expressly list specific government actions that are categorically exempt from SEPA review. Instead, RCW 43.21C.037 merely refers to the Forest Practices Board, which has discretionary authority under RCW 76.09.050 to define forest practices classes I to IV.
¶42 But we need not decide whether RCW 43.21C-.037 is a purely statutory exemption or a so-called “hybrid exemption.” In either case, as we discuss above, RCW 43-.21C.110(l)(a) is limited to Ecology’s categorical exemptions listed under WAC 197-11-800. RCW 43.21C.110(l)(a) does not apply to exemptions listed under other SEPA provisions.
¶43 RCW 43.21C.037 provides:
(1) Decisions pertaining to applications for Class I, II, and III forest practices, as defined by rule of the forest practices board under RCW 76.09.050, are not subject to the requirements of RCW 43.21C.030(2)(c)[25] as now or hereafter amended.
(3) Those forest practices determined by rule of the forest practices board to have a potential for a substantial impact on the environment, and thus to be Class IV practices. . . .
(Emphasis added.)
*396¶44 By its plain language, RCW 43.21C.037 grants the Forest Practices Board sole discretion to determine (1) which activities fall under which forest practices classification26 and (2) which actions may substantially impact the environment, under both SEPA and the Forest Practices Act,27 regardless of Ecology’s determination or rules under RCW 43.21C.110(l)(a).28
¶45 The Forest Practices Board alone (1) defines class IV forest practices, which are subject to environmental review, and (2) decides whether a segmented class III permit application, for example, should be considered and treated as a class IV forest practice. If, as ALPS urges, we were to interpret RCW 43.21C.110(l)(a) as allowing Ecology to apply its cumulative effects Rule 305 to forest practices, then essentially we would be (1) granting Ecology the right to define forest practices classifications and (2) judicially amending the legislature’s delegation to the Forest Practices Board the sole authority to classify forest practices. Such interpretation not only would be an improper judicial usurpation of legislative authority but also would be contrary to the legislature’s clear mandates in RCW 43-.21C.037 and RCW 76.09.050. Instead, as we previously noted, it is our judicial duty to read the legislature’s statutes together, in harmony where possible, to carry out the legislature’s intent. See, e.g., Nisqually Delta Ass’n, 103 Wn.2d at 730.
¶46 Thus, contrary to ALPS’ contentions, we hold that Ecology has no authority to apply WAC 197-11-305 exceptions to forest practices permits under RCW 43.21C.037.29
*397IV. Forest Practices Board’s Rule-Making Duty
¶47 ALPS further argues that, when read together, SEPA and the Forest Practices Act create a mandatory duty for the Forest Practices Board to promulgate a class IV-special catch-all provision to ensure SEPA review for all forest practices with potentially significant cumulative effects. This argument also fails.
¶48 As quoted earlier, SEPA explicitly exempts class I, II, and III forest practices from an EIS requirement. RCW 43.21C.037. The plain language of this exemption expressly contemplates the Forest Practices Board’s defining, by rule making, which forest practices are not subject to SEPA review.
¶49 The source of this contemplated rule-making authority is RCW 76.09.040(1) of the Forest Practices Act. RCW 76.09.040(1) requires the Forest Practices Board to adopt such rules as “necessary to accomplish the purposes and policies stated in RCW 76.09.010.” As we note above, RCW 76.09.010’s purposes and policies include both “a viable forest products industry” as well as “natural resource protection,” including “forest soils, fisheries, wildlife, water quantity and quality, air quality, . . . and scenic beauty.”
¶50 RCW 76.09.040(1) of the Forest Practices Act thus requires the Forest Practices Board to balance these considerations when it promulgates forest practice rules. In striking this balance, the Forest Practices Board must include within class IV those forest practices that “have a potential for a substantial impact on the environment”30 and, therefore, trigger DNR to evaluate whether SEPA requires an EIS. RCW 76.09.050(1). In WAC 222-16-050(1), the Forest Practices Board has struck this balance.
¶51 WAC 197-11-305 (namely, Rule 305) is purely an Ecology rule, applicable only to Ecology actions; it does not apply to the Forest Practices Board. In contrast, no rule or *398statute requires the Forest Practices Board to consider cumulative effects when it classifies forest practices.31 Although the Forest Practices Board may, if it chooses, adopt a cumulative effects rule of its own volition,32 it has not yet so acted.
¶52 We reject ALPS’ argument that the Forest Practices Board must promulgate a cumulative effects rule.33 That such a rule would be consistent with the Forest Practices Act does not mean that the Forest Practices Board has a statutory duty to promulgate such a rule. On the contrary, our research reveals no statute imposing such a duty.
¶53 Consistent with this conclusion is Snohomish County v. State, 69 Wn. App. 655, 665, 850 P.2d 546 (1993), review denied, 123 Wn.2d 1003 (1994), vision One of our court addressed whether SEPA generally applies to class III forest practices. Division One held:
[T]he Legislature’s exemption of class III forest practices from SEPA spares DNR .. . from individual case-by-case environmental review. The Legislature intended to prevent unnecessary paperwork, delays, and bureaucratic processing that would be a significant burden on government and taxpayers.
Id. at 669. The court reasoned:
For classes I, II, and III, the Legislature did not intend for DNR to comply with all the procedural steps necessary to determine if an EIS is required. The contention of the County and [Washington Environmental Council] that SEPA applies to all forest practices applications is rejected. SEPA’s EIS require*399ments do not apply to the first three classes of forest practices, unless by operation ofWAC 197-11-305(1).
Id. (emphasis added).
¶54 Thus, under Snohomish County, unless Rule 305 applies, otherwise exempt forest practices (such as class III forest practices) are not subject to SEPA environmental review. Because Ecology properly removed classes I, II, and III forest practices from the Ecology rules to which Rule 305 applied, there is no longer a cumulative-effects exception rule applicable to these three classes of forest practices. Under the Snohomish County rationale, it is consistent with the legislature’s intent that SEPA-exempt forest practices, as enumerated in the Forest Practices Board’s rules, are not subject to environmental review under SEPA.
¶55 Accordingly, we hold that the Forest Practices Board has no statutory, or other, duty to promulgate a catch-all, Rule 305-type provision in its forest practices rules that would apply SEPA environmental review to otherwise exempt forest practices with potentially substantial cumulative effects. We further hold that, because the Forest Practices Board had no duty to promulgate a 305-type rule, the Forest Practices Board did not act arbitrarily and capriciously in denying ALPS’ petition for rule making.34
¶56 Affirmed.
Bridgewater and Armstrong, JJ., concur.