¶ 1. The Department of Workforce Development and eight individual claimants appeal a circuit court order which reversed the department's determination that the claimants' employer had violated the Wisconsin Family and Medical Leave Act (WFMLA).1 At issue is whether the *383department correctly concluded that the claimants could substitute paid sick leave for family leave commencing with the first day of family leave, irrespective of a "waiting period" which applied to Oscar Mayer's contractual sick leave benefit. We conclude that we must accord the department's interpretation and application of the WFMLA great weight deference, and under that standard of review, we affirm the department's ruling. Accordingly, we reverse the order of the circuit court and direct that on remand the department's determination and order be reinstated.
BACKGROUND
¶ 2. Oscar Mayer provides sick leave benefits to its employees of one year or more pursuant to a collective bargaining agreement. The benefits consist of a number of days of partial-wage payments, with the number of days dependant on an employee's length of service.2 Paid sick leave does not begin until the fourth or eighth day of absence due to illness.3 Several Oscar *384Mayer employees asked to substitute paid sick leave benefits for family leave from the first day of absence for family leave. Oscar Mayer denied the substitution requests for the first few days of each family leave.4
¶ 3. The present claimants and several other Oscar Mayer employees who were denied their full substitution requests filed claims with the department. Employee Kent Pagel, not a claimant in this case, brought the first claim that was heard and decided by the department. In Pagel's case, the department determined in April 1998 that Oscar Mayer's sick leave benefits were "accrued" for purposes of WlS. Stat. § 103.10(5)(b) (1999-2000),5 and that Oscar Mayer must allow the substitution commencing with the first day of family leave.6 Oscar Mayer petitioned for judicial review of the Pagel decision to the Dane County Circuit Court.
¶ 4. The present case began as a consolidation of the claims of nine employees with different types and lengths of family leaves taken in March through August 1998. After the hearing and briefing in this case, but before a decision by the department, the circuit court affirmed the Pagel decision. The department, *385over Oscar Mayer's objection, placed "in abeyance" a decision in this case to await the disposition of Oscar Mayer's appeal of the Pagel decision to this court. Oscar Mayer then withdrew its appeal of Pagel, and claimants moved the department for a determination in their favor based on issue preclusion. The department decided that: (1) it need not reach the merits because Oscar Mayer's withdrawal of its appeal rendered the Pagel decision final, and thus, Oscar Mayer was precluded from relitigating the issues at hand; and (2) even if issue preclusion did not apply, the claimants should prevail on the merits. The department expressly adopted its prior decision in Pagel, and it rejected Oscar Mayer's new argument that allowing substitution of the sick leave without the waiting period would impose "unanticipated costs."7
¶ 5. Oscar Mayer petitioned for judicial review. The circuit court concluded that (1) the department erred in concluding that issue preclusion bars Oscar Mayer from litigating the issue of leave substitution and its "unanticipated costs"; (2) the department correctly determined that Oscar Mayer's paid sick leave benefit was "accrued" leave under Wis. Stat. § 103.10(5)(b) and Wis. Admin. Code § DWD 225.03; but (3) the department's determination permitting substitution of the paid sick leave for the first few days of a family leave was contrary to the Wisconsin Supreme Court's decision in Richland School District v. DILHR, 174 Wis. 2d 878, 901, 498 N.W.2d 826 (1993). The claimants and the department appeal the circuit court's decision and order.
*386ANALYSIS
¶ 6. The claimants first argue that issue preclusion bars Oscar Mayer from relitigating the central issue in this case. For reasons we discuss below, we conclude that the department did not err in interpreting and applying WlS. Stat. § 103.10. Because we agree with the claimants on the merits, we do not address their issue preclusion argument. See Benkoski v. Flood, 229 Wis. 2d 377, 388, 599 N.W.2d 885 (Ct. App.), review denied, 230 Wis. 2d 273, 604 N.W.2d 571 (Wis. Sept. 28, 1999) (No. 98-1972).
¶ 7. We review the department's decision, not that of the circuit court. Stafford Trucking, Inc. v. DILHR, 102 Wis. 2d 256, 260, 306 N.W.2d 79 (Ct. App. 1981). The initial dispute in this appeal, however, as in many involving our review of administrative agency decisions, is over the degree of deference we are to accord the department's decision. The supreme court has described the hierarchy of deference under which a court is to review an administrative agency's conclusions of law and statutory interpretation as follows:
First, if the administrative agency's experience, technical competence, and specialized knowledge aid the agency in its interpretation and application of the [law], the agency determination is entitled to "great weight." The second level of review provides that if the agency decision is "very nearly" one of first impression it is entitled to "due weight" or "great bearing." The lowest level of review, the de novo standard, is applied where it is clear from the lack of agency precedent that the case is one of first impression for the agency and the agency lacks special expertise or experience in determining the question presented.
*387Jicha v. DILHR, 169 Wis. 2d 284, 290-91, 485 N.W.2d 256 (1992) (citations omitted).
¶ 8. The claimants urge us to give the department's interpretation "great weight," while Oscar Mayer argues that we must review it de novo. We conclude that the department's interpretations of the WFMLA, and of its own rules implementing the act, are entitled to great weight deference. The supreme court in Richland School District reviewed the department's interpretation of the same statute and rule that are at issue in this case. The court explained that the department went through a rule-making process and adopted administrative rules interpreting the meaning of the leave substitution provision of WlS. STAT. § 103.10(5)(b). Richland School District, 174 Wis. 2d at 891 — 94. In view of the "experience and expertise in interpreting the substitution provision" which the department gained thereby, the court granted the department's interpretation great weight deference. Id. at 894. Accordingly, we do likewise here.8
*388¶ 9. When reviewing an agency decision under the great weight standard, we will uphold an agency's reasonable statutory interpretation even if we might also conclude that an alternative interpretation is more reasonable. UFE Inc. v. LIRC, 201 Wis. 2d 274, 287, 548 N.W.2d 57 (1996). Thus, our task is to determine whether the department's determination that Oscar Mayer's sick leave benefit constitutes an accrued paid leave that may be substituted for family leave under Wis. Stat. § 103.10(5)(bj, commencing with the first day of family leave, is "merely reasonable." See Harnischfeger Corp. v. LIRC, 196 Wis. 2d 650, 661, 539 N.W.2d 98 (1995). If the determination does not directly contravene the words of § 103.10, or the legislature's intent when enacting the WFMLA, and if the department's interpretation has a rational basis, our inquiry is at an end and we must affirm the department's order. See id. at 662.
¶ 10. We begin with the language of the statute and the department's rule interpreting it. The WFMLA *389does not require employers to pay employees for approved family leaves. WlS. STAT. § 103.10(5)(a). However, § 103.10(5)(b) provides that "[a]n employee may substitute, for portions of family leave or medical leave, paid or unpaid leave of any type provided by the employer." The department has promulgated the following administrative rule interpreting the statutory provision: "At the option of the employe, an employe entitled to family or medical leave under the act may substitute, for any leave requested under the act, any other paid or unpaid leave which has accrued to the employe." Wis. Admin. Code § DWD 225.03(1) (emphasis added). To prove a violation of § 103.10(5)(b), the claimants must establish that: (1) at the time they requested leave, they were covered by the WFMLA; (2) they asked to substitute other leave for family leave; (3) Oscar Mayer provided other leave that could be substituted; (4) each claimant had accrued the leave to be substituted; and (5) Oscar Mayer denied the substitution request. Miller Brewing Co. v. DILHR, 210 Wis. 2d 26, 31, 563 N.W.2d 460 (1997) (citing Leher v. Consolidated Papers, Inc., 786 F. Supp. 1480, 1485 (W.D. Wis. 1992)). The third and fourth elements are at issue in this case.
¶ 11. Oscar Mayer first argues the department erred in concluding that the claimants had "accrued" sick leave as required under Wis. Admin. Code § DWD 225.03.9 Oscar Mayer asserts that an accrued leave *390benefit "must be vested, it must not be contingent, and its substitution under the WFMLA must not impose 'unanticipated costs' on the employer." The claimants respond that an accrued leave benefit is simply one that is quantifiable and calculable in specified amounts. Both parties assert that support for their positions may be found in Richland School District, where the supreme court stated:
Only those types of leave which an employment contract allows an employe to accumulate over time are available for substitution. Leave which is indefinite or which cannot be quantified at the time of the FMLA leave request is not "leave ... provided by the employer" under FMLA. Such indefinite, incalculable leave is distinguishable from the leave in this case, which accrues into specified, calculable amounts of time. The parties agree that the collective bargaining agreement gave Ruder 18 days of accumulated paid leave. He requested authorization to substitute five of those days for the unpaid leave to which he was entitled under FMLA. He was not asking to substitute any form of non-accrued, discretionary or contingent leave time which the school district might give him upon request.
*391Id. at 895-96.
¶ 12. The department determined in this case that leave is accrued within the meaning of WlS. ADMIN. Code § DWD 225.03 if it arises from a contract, is specified and quantifiable, has a "draw-down" feature, and is the type of leave that an employee is allowed to accumulate over time. The department concluded that the Oscar Mayer sick leave benefit meets these criteria, and that the claimants thus had accrued sick leave available to them for substitution under WlS. STAT. § 103.10(5)(b). We conclude that the department reasonably interpreted and applied the term "accrued" in its rule to the facts of this case.
¶ 13. The department's criteria for accrued leave are reasonably based on the meaning of the term,10 and they are not in conflict with the supreme court's discussion in Richland School District, quoted above. The department, after applying the criteria to the present facts, reasonably concluded that sick leave had "accrued" to the claimants in this case. First, the benefit arises from the parties' collective bargaining agreement. Second, the amount of paid sick leave available to a given employee is specified and quantifiable. For example, if an employee has worked at Oscar Mayer for six years, he or she has ten weeks of sick leave available in a twelve-month period. Third, the benefit has a "draw-down" feature, by which the *392amount of available leave decreases as the employee uses it.11 Fourth, although there is no leave "carryover" feature, the benefit "accumulates" over time because (1) the amount of leave available renews to the maximum every twelve months, and (2) the maximum amount of leave available increases with an employee's longevity.12
¶ 14. In Oscar Mayer's view, the department's determination that the present sick leave benefit creates "accrued" leave is unreasonable and inconsistent with Richland School District, which, according to Oscar Mayer, requires that an accrued, substitutable leave be "a vested, earned, or existing right or benefit." Oscar Mayer asserts that the claimants have no vested right in the sick leave benefit because (1) the leave does not "accumulate" over time, but rather must be used within one year, and (2) it is contingent on an employee being sick for several days before receiving a paid benefit. Oscar Mayer equates its sick leave benefit with that provided under a typical disability insurance policy.
¶ 15. Although the sick leave benefit in the parties' collective bargaining agreement may resemble a disability insurance policy, we agree with the department that any such resemblance is irrelevant.13 The *393issue is whether the sick leave benefit meets the requirements as a substitute leave under the WFMLA, and, as we have discussed, the department reasonably concluded that it does. Oscar Mayer's sick leave benefit "accumulates over time" by renewing annually and increasing with an employee's seniority. And, the fact that an employee must be sick for several days before receiving paid sick leave benefits does not render the benefit "indefinite" or "incalculable." Once the waiting period requirement is met, the entitlement is clear and Oscar Mayer may not, in its discretion, deny a request for payment of the benefit. See Richland School District, 174 Wis. 2d at 898.
¶ 16. Even though the presence of the sick leave waiting period does not render unreasonable the department's conclusion that the leave accrues and is substitutable under Wis. Stat. § 103.10(5)(b), it does not necessarily follow that Oscar Mayer must allow substitution commencing on the first day of family leave, as the department also concluded. Oscar Mayer argues that, even if its sick leave is accrued and can be substituted under the WFMLA, a claimant may only be paid for days of family leave beyond the waiting period. Allowing substitution of the sick leave benefit from the first day of a family leave, according to Oscar Mayer, imposes "unanticipated costs," and thus conflicts with the supreme court's observation in Richland School District that "[t]hrough sec. 103.10(5)(b), the legislature has made it possible for employes to draw down on *394their leave accounts during FMLA leave, without imposing unanticipated costs on the employer." Id. at 901 (emphasis added).
¶ 17. The department reasoned, however, that the claimants could substitute paid sick leave from the first day of leave because, as explained in Richland School District, an employee need not satisfy "the conditions of leave eligibility set forth in the collective bargaining agreement before substitution is allowed" under the WFMLA. Id. at 898. The department assumed that employees would use more of their available sick leave if substitution for family leave were allowed than if it were not. It concluded, however, that this would only constitute increased "use costs," not "unanticipated costs."
¶ 18. We conclude that it was not unreasonable for the department to reject Oscar Mayer's "unanticipated costs" argument. We note first that the supreme court's use of the phrase in Richland School District, was at most a passing comment in its discussion of the legislative purpose behind WlS. Stat. § 103.10(5)(b). A prohibition against imposing "unanticipated costs" was not central to its holding. Indeed, the court noted later in the opinion that the "substitution provision increases the opportunities for a state employe to use existing accrued paid leave, as opposed to creating additional paid leave." Id. at 904. There can thus be no question that the supreme court was well aware that permitting the substitution of paid leave for unpaid family leave would inevitably result in increased usage of existing paid leave benefits, benefits that might otherwise go unused. We agree with the department, however, that that fact alone cannot be used as a justification for denying substitution, under either the *395language of the statute or the court's discussion in Richland School District. Permitting substitution in this case neither increases the maximum number of paid sick leave days available to any employee nor eliminates the "draw-down" of available benefits when either sick leave or family leave is taken.
¶ 19. As we have noted, the department concluded that the three- or seven-day waiting period required before an employee is entitled to paid sick leave, is a non-transferring "condition" of the sick leave benefit, similar to the requirement for a "disability caused by sickness or accident." In its de novo consideration of the issue, the circuit court concluded that the waiting period was "more properly" viewed as a factor in the accrual determination. That is, just as no sick leave benefit accrues to an employee during his or her first year of employment with Oscar Mayer, so, too, in the circuit court's view, no sick leave should be deemed to accrue to an employee until the specified number of days of absence from work has passed.
¶ 20. The circuit court's interpretation may well be no less reasonable than the department's. As the circuit court itself recognized in another part of its decision, however, it is precisely in the interpretation and application of its "accrued leave rule," WlS. Admin. Code § DWD 225.03(1), that we must accord the department the greatest deference. See Richland School District, 174 Wis. 2d at 894. We are not persuaded that the department's interpretation that Oscar Mayer's sick leave benefit accrues irrespective of the waiting period, and that the waiting period requirement is a non-transferring condition when sick leave is substituted for family leave, contravenes either the language of the WFMLA or the legislature's intent when enacting it. *396The department's interpretation also has a rational basis and comports with the holding of Richland School District. See id. at 898. In short, the department's interpretation is a reasonable one and must be affirmed.
¶ 21. Finally, we observe that classifying the waiting period as a non-transferring condition of eligibility, as opposed to an element determining accrual, may represent a policy choice as much as it does a legal interpretation. If so, the choice is the department's to make, not ours. See Roehl Transport, Inc. v. Wisconsin Div. of Hearings and Appeals, 213 Wis. 2d 452, 459 n.5, 570 N.W.2d 864 (Ct. App. 1997) (We "pay great deference to an agency's interpretation when it is intertwined with value and policy determinations inherent in the role the legislature assigned the agency to play.").
CONCLUSION
¶ 22. For the reasons discussed above, we reverse the appealed order and direct that the department's decision and order be reinstated in its entirety.
By the Court. — Order reversed and cause remanded with directions.