¶68 (dissenting in part) — Our task today is to determine the meaning of the overriding consideration of the public interest (OCPI) standard. But rather than engaging with the statutory text, the legislative history, or the facts of this case, the majority relies on the general contours of the prior appropriation principle of water allocation. Because minimum flows constitute a vested water right, the majority reasons, the OCPI exception to vested water rights does not apply. This theory not only borders on the tautological, but fails to provide meaningful guidance on the statutory scheme. In other words, the majority explains why not every beneficial use will necessarily constitute an OCPI but never explains why no beneficial use can ever be an OCPI. Specifically, the majority does not explain why a significant benefit to communities underserved by existing water supplies, with a minimal impact on instream flows, cannot be an OCPI. The legislative history of the Water Resources Act of 1971 (hereinafter WRA) (chapter 90.54 RCW) indicates that the majority is reading the OCPI exception too narrowly, and the Department of Ecology’s data indicate that the critical water needs of rural and exempt-well users can be served with a very minor reservation. Therefore, I dissent in part.18
I. Statutory analysis
¶69 The minimum flow levels on which the majority relies exist by virtue of the Minimum Water Flows and Levels Act of 1969, chapter 90.22 RCW (hereinafter MWFLA). The *604MWFLA does not exist in a vacuum, nor does it establish nigh-unconditional protection over minimum flows, as the majority reads it to do. Majority at 576 (“The exception is very narrow, however, and requires extraordinary circumstances before the minimum flow water right can be impaired.”). The reality is more complex: the legislature almost immediately revisited the MWFLA in order to temper its effects when it passed the WRA.
¶70 The relevant sections, RCW 90.22.010 through .030, were enacted in 1969. Laws of 1969, 1st Ex. Sess., ch. 284, §§ 3-5. In the same year, the legislature established the Legislative Committee on Water Resources to develop provisions for the expansion of agricultural irrigation as well as for other present and reasonably foreseeable water needs. Substitute H. Con. Res. 15,41st Leg., Ex. Sess. (Wash. 1969) (on file with Wash. State Archives). The committee examined the MWFLA and determined that
if state government is to reserve waters for one use ... , it is obligated then to reserve for all beneficial uses, and that such reservation procedures place said beneficial uses on a par, i.e., that all uses receive consideration in a single planning and reservation process.
Legis. Water Resources Comm., Final Report of Findings to 42d Legislature Pursuant to Provisions of Substitute H. Con. Res. 15, cmt. at 6 (Jan. 1971) (on file with Wash. State Archives). That is, the committee understood minimum flows to constitute only one of many beneficial uses to be considered “on a par” with one another. Four members of the committee went on to author the bill that became the WRA. Significantly, the OCPI exception was adopted unchanged. Compare Engrossed H.B. 394, § 2(3)(a), 42d Leg., 1st Ex. Sess. (Wash. 1971), with RCW 90.54.020(3)(a).
¶71 In short, the fact that the drafters of the WRA specifically named the MWFLA in their report, as well as the proximity in time of the two enactments, places it beyond dispute that the WRA was meant to modify or *605clarify the mandates of the MWFLA in some way. And the drafters’ own words indicate that when they authored the very same OCPI language that we now interpret, their intent was to secure equitable treatment for minimum flows and for competing water interests. Final Report of Findings to 42d Legislature, supra, cmt. at 6.
¶72 Furthermore, the fact that minimum flows constitute vested appropriations of water does not make them immutable.19 As this court has recognized, Ecology may impinge on extant water rights in the course of setting mínimum flows. Pub. Util. Dist. No. 1 of Pend Oreille County v. Dep’t of Ecology, 146 Wn.2d 778, 817-18, 51 P.3d 744 (2002).20 If Ecology may impinge on prior appropriations through rule making in one context, and minimum flows are to be treated as any other prior appropriation, then it stands to reason that Ecology may impinge on minimum flows by rule in some circumstances. We should look to the legislative history, and to the MWFLA’s specific provisions for the “subsequent modification” of minimum flow rules, to determine what circumstances justify modification. RCW 90.22.020. If we accept the majority’s strict reading of the OCPI exception, then Ecology’s statutory authority to modify minimum flows is really only statutory authority to increase the minimum flows because there will *606be so few situations in which Ecology may decrease the minimum flows. There is no evidence that the legislature intended the water statutes to work as a one-way ratchet, and such an interpretation flies in the face of the legislature’s clearly expressed intent to treat minimum flows and other beneficial uses equally.
II. Factual analysis
¶73 In light of the legislature’s intent to place all beneficial uses “on a par,” it is puzzling that the majority does not engage with the record, let alone with Ecology’s hydrological analysis. Doing so reveals that a reservation as small as 1.5 cfs (cubic feet per second) for exempt-well users and rural public water systems would avoid significant costs on behalf of these underserved communities and would have little if any impact on environmental and aesthetic interests. Such an unequivocal net benefit comports with a plain reading of the term “overriding.”
¶74 In the absence of a prior interpretation of the language “overriding consideration of the public interest,” I proceed with a textual analysis. First, we must identify a “consideration of the public interest,” and then we must determine whether that consideration “overrides” all competing considerations. That is, we must determine whether the benefit to the public interest from a given reservation would “dominate or prevail over” the associated costs. Webster’s Third New International Dictionary 1609 (2002) (defining “override”). Of course, costs and benefits may be commensurable or incommensurable. But the very existence of the OCPI exception indicates that there will be some cases in which the combined benefits will so clearly override the combined costs that an exception to the prior appropriation rule will be warranted.
¶75 Many of the new reservations under the “Amended Rule,” indeed, do not rise to that standard. The Amended Rule would allocate 5.5 cfs to large public water purveyors, at an estimated benefit of $104,000. Administrative Record *607(Admin. R.) at 002868. The Amended Rule would allocate 10 cfs for agricultural irrigation, at an estimated benefit of $3.7 million. Id. at 002869, 002871. The Amended Rule would allocate 0.5 cfs of water for stock watering purposes at “no cost and no gain” to the public. Id. at 002872. While Ecology did not calculate individual cost estimates for these reservations, it estimated that the economic costs (mostly comprising impacts on migratory fish populations) of the full 25 cfs reservation would be $6 to $6.7 million. Id. at 002880. Even the sum of all the economic benefits of the above three reservations is less than this cost figure. The economic costs are so great that we may conclude that the reservations for large public water purveyors, agricultural irrigation, and stock watering are not overriding considerations of the public interest, without resort to incommensurable costs and benefits.
¶76 But the final reservation category — rural public water systems and permit-exempt wells — deserves a closer look. According to Ecology’s estimates, 9,766 people relied on permit-exempt wells in 2005, a figure that will increase to 17,501 by 2025. These people will require an additional 0.81 cfs to serve average household needs. Rural public water systems will require an additional 0.36 and 0.69 cfs between now and 2025. In total, then, these needs could be met with a reservation of 1.5 cfs or less. This is less than 1 percent of the 200 cfs of interruptible water rights created by the instream flow rule (Rule)21 and less than 0.03 percent of the Skagit River’s average flow during the dry season.22
¶77 Now consider the alternative. Without these 1.5 cfs reservations, rural public water system or exempt-well users are left without water for up to 20 days of some *608months and are left with a few onerous choices. One choice, according to Ecology’s cost benefit analysis, is to store sufficient water to last through the dry season. This would require about three months’ worth, or tens of thousands of gallons. Secondly, users might purchase agricultural farmland with uninterruptible water rights and transfer the rights to their homes, thus reducing the State’s supply of irrigated farmland. A third choice is to develop an Ecology-approved mitigation plan, which would require a hydrological analysis; professional hydrological investigation may be very expensive.23 Finally, if none of these options is feasible, users may be left with no choice but to abandon their land, downgrading building lots to pieces of dry farmland. In total, the costs that would be avoided by a 1.5 cfs reservation for rural public water system and exempt-well users alone would be in excess of $29 million.
¶78 The interests on the other side of the equation include incommensurables such as fish spawning and recreational enjoyment of the waters of the Skagit River. To be sure, these are important interests that Ecology is not at liberty to ignore. And indeed, Ecology properly took the incommensurables into account and incorporated them into its analysis when it determined that the amended instream flow rule (Amended Rule)24 was supported by OCPI. Ecology determined in its expert capacity that the full 25 cfs reservation provided by the Amended Rule would decrease the populations of chinook, coho, and cutthroat salmon, and other perennially spawning fish by 0.5 percent.25 Surely the impact would be even less if we reduced the reservation 16-fold, limiting Ecology to the 1.5 cfs reservation necessary for rural public *609water system and exempt-well users.26 Furthermore, there are incommensurables in favor of the Amended Rule as well. As Ecology notes in its brief, the reservations created by the Amended Rule are not merely a matter of economic benefit but rather a matter of necessity to make rural development and lifestyles in the Skagit River basin possible at all.
¶79 The majority argues that Ecology categorically may not rely on cost-benefit analysis in determining OCPI for fear that “the need for potable water for rural homes [will be] virtually assured of prevailing over environmental values.” Majority at 587. No party has called for such an inflexible test, and neither do I. This is not simply a case where the benefits are greater than the costs but where the benefits of the 1.5 cfs reservation in particular are significant and the costs are close to nothing. That is, the record clearly indicates that the 1.5 cfs reservation for rural public water system and exempt-well users would bring significant value to users underserved by traditional water supplies, at a nominal cost to fish populations and other ecological and aesthetic interests. If such an overwhelming benefit does not “override,” that is, to “dominate or prevail over” the marginal impact on fish, it is difficult to determine what would. Webster’s, supra, at 1609. If the OCPI exception were reserved for truly “extraordinary circumstances” as the majority reads it to be, majority at 576, then the legislature could have enumerated such “extraordinary circumstances,” such as fires or other emergencies. The legislature did not do so, and when it passed the WRA, it made clear that minimum flows were to be treated equally with and not greater than competing water interests. It is difficult to square this legislative intent with the majority’s willingness to sacrifice significant socioeconomic interests *610for the sake of a miniscule proportion of a select number of fish populations.
¶80 Of course, this court is not a finder of fact. While it seems likely that a reservation of 1.5 cfs would have even less of an impact on environmental and aesthetic interests than would the full 25 cfs reservation envisioned by the Rule — and perhaps even no impact at all — we cannot say for certain. Ecology’s hydrological expertise places it in a better position to determine the impact (or lack of impact) of a 1.5 cfs reservation for exempt-well users and rural public water systems. Therefore, I would remand this case with instructions to Ecology to analyze the ecological impact of the 1.5 cfs reservation. If Ecology finds that a reduction of 1.5 cfs would produce benefits to the public interest that clearly override the harms — for instance, a reduction in fish populations of a hundredth of a percent or less — then the reservations should be permitted. If not, then I would agree with the majority.
¶81 I respectfully dissent.
J.M. Johnson, J., and Chambers, J. Pro Tem., concur with Wiggins, J.I contest the majority’s holding only as to the 1.17 to 1.5 cubic feet per second (cfs) reserved for exempt-well users and rural public water systems, as described below. The majority correctly invalidates the remaining 23.5 cfs of reservations created by the amended instream flow rule (Amended Rule) (see majority at 578 n.2).
This analysis assumes that the minimum flows created by the instream flow rule (Rule) can be thought of as vested rights in the first place. The amendments to the Rule came about as a direct result of an Administrative Procedure Act, chapter 34.05 RCW, challenge to the Rule. This judicial challenge put the original minimum flows under a cloud of doubt that was resolved only when the litigation settled as a result of Ecology’s Amended Rule. Of course, Ecology may not reach a rule through settlement that it could not lawfully reach through the rule making process. But the majority’s reliance on the vested nature of prior appropriations evades the key question of how we are to interpret the OCPI exception.
As the majority notes, Public Utility District No. 1 addressed a different statutory scheme from the minimum flows at issue here. Majority at 601 n.17 (citing Pub. Util. Dist. No. 1, 146 Wn.2d at 820-21). This is a distinction without a difference: the essential holding of Public Utility District No. 1 is that in some cases, Ecology may override a prior appropriation through rule making. 146 Wn.2d at 821. The majority’s assertion that prior appropriations are, essentially, an absolute barrier to Ecology’s rule making power is more akin to the dissent in Public Utility District No. 1. Id. at 836-37 (Sanders, J., dissenting).
See majority at 578 n.2.
During the low flow season in the early fall, the Skagit River Watershed averages 5,970 cfs. The average flow for the whole year is 16,560 cfs, over 11,000 times the amount of water needed by rural public water system and exempt-well users.
The town of Hamilton’s Little Carey’s Creek mitigation plan, for instance, cost over $750,000.
See majority at 578 n.2.
Ecology estimates that fish that spawn in the late fall and depart for the ocean by spring, such as pink, chum, and fall chinook salmon, would not be affected at all.
If a reservation of 25 cfs is expected to cause as much as $6.7 million in harms to fish populations, Admin. R. at 002880, then simple arithmetic suggests that a reservation of 1.5 cfs will cause less than half a million dollars in damage.