dissenting:
At issue in this ease is whether the Colorado Water Conservation Board (CWCB) has the authority to redetermine and administratively reduce a decreed instream flow right, and, if so, whether the CWCB’s decision was supported by substantial evidence. The majority holds that, because the water court has “exclusive jurisdiction” over water matters, “once a decree is issued on the [CWCB’s] application determining the instream flow ... necessary to preserve the natural environment to a reasonable degree, the Board cannot unilaterally modify and must implement the decree unless and until its rights are modified, after application for change, filed with the water court.” Maj. op. at 1261.
Because I do not find this holding to be supported by the express or implied terms of the statutory scheme governing instream flow rights, I respectfully dissent. I would hold that (1) the CWCB need not seek modification of an instream flow decree in water court before deciding not to seek enforcement of its full decreed right; and (2) the CWCB’s decision to enforce less than the decreed instream flow right for Snowmass Creek is supported by substantial evidence.
Pursuant to the Colorado Administrative Procedure Act (APA), §§ 24-4-101 to 108, 10A C.R.S. (1988 & 1994 Supp.), Aspen Wilderness Workshop, Inc., (AWW) challenges CWCB’s decision to enforce less than its full instream flow right.1 Under the APA,
*1262any person adversely affected or aggrieved by any agency action may commence an action for judicial review in the district court....
§ 24-4-106(4). If the district court
finds no error, it shall affirm the agency action. If it finds that the agency action is arbitrary or capricious, a denial of statutory right, contrary to constitutional right, power, privilege, or immunity, in excess of statutory jurisdiction, authority, purposes, or limitations, not in accord with the procedures or procedural limitations of this article or as otherwise required by law, an abuse or clearly unwarranted exercise of discretion, based upon findings of fact that are clearly erroneous on the whole record, unsupported by substantial evidence when the record is considered as a whole, or otherwise contrary to law, then the court shall hold unlawful and set aside the agency action and shall restrain the enforcement of the order or rule under review, compel any agency action to be taken which has been unlawfully withheld or unduly delayed, remand the case for further proceedings, and afford such other relief as may be appropriate.
§ 24-4-106(7) (emphasis added). The district court found that the CWCB’s decision was not in excess of its authority and was supported by substantial evidence and granted summary judgment in favor of CWCB. Because I would hold that the CWCB acted within its statutory authority, I must address both issues.
I.
The majority asserts that “[sjection 37-92-102, in giving the [CWCB] its authority to appropriate water, did not grant the [CWCB] the power to unilaterally modify lawful decrees of the water court.” Maj. op. at 1259.2 *1263The majority farther asserts that the CWCB may not take less than its full decree without water court adjudication because under this statute the CWCB is “imbued with unique statutory responsibilities.” id. at 1259, and “has a unique statutory fiduciary duty to protect the public in the administration of its water rights decreed to preserve the natural environment,” id. at 1260. I disagree.
AWW has not argued that the CWCB has a “fiduciary duty” to protect the public and the majority does not provide any authority supporting its conclusion that section 37-92-102(3) imposes such a duty. Maj. op. at 1259-60. AWW asserts that section 37-92-102(3) imposes a “public trust” on CWCB by granting CWCB authority to hold instream flow rights “on behalf of the public.” This court has never recognized the public trust doctrine with respect to water. Furthermore, whatever the nature of the fiduciary duty recognized by the majority in this case, I do not understand the majority to mean that a breach of this fiduciary duty would support a public claim for damages.
Nevertheless, to the extent that the majority uses “fiduciary duty” as analogous to a public trust responsibility, that duty is fulfilled as long as the CWCB has acted within its authority under section 37-92-102(3). See Black’s Law Dictionary 563 (5th ed. 1979) (defining “fiduciary” as analogous to a trust” or as “a person or institution who manages money or property for another and who must exercise a standard of care in such management activity imposed by law or contract”). The term “public trust doctrine” refers to a common law concept that imposes on the government the duty “to preserve and protect the public lands for the public’s common heritage.” See Sierra Club v. Block, 622 F.Supp. 842, 866 (D.Colo.1985) (acknowledging the existence of the public trust doctrine applicable to federal lands, but rejecting Sierra Club’s claim based on the doctrine). The term also has been used to designate the public’s right of use and access to navigable waterways. See People v. Emmert, 198 Colo. 137, 141, 597 P.2d 1025, 1027 (1979) (rejecting the public trust as a basis for assuring public recreational use of water overlying privately owned stream beds of non-navigable waterways).
In any event, the concept of a public trust has no independent content. As the Supreme Court said, “it is not for the courts to say how that trust shall be administered.” Light v. United States, 220 U.S. 523, 537, 31 S.Ct. 485, 488, 55 L.Ed. 570 (1911). Where the legislature has provided statutory directives for the management and protection of public resources, “those statutory duties ‘comprise all the responsibilities which defendants must faithfully discharge.’ ” Sierra Club, 622 F.Supp. at 866 (citing Sierra Club v. Andrus, 487 F.Supp. 443, 449 (D.D.C.1980)) (emphasis in original); Light, 220 U.S. at 537, 31 S.Ct. at 488.
In this case, section 37-92-102(3) gives the CWCB authority to appropriate water for minimum stream flows “on behalf of the people.” However, to the extent this provision imposes a “public trust” responsibility on the CWCB similar to that of the federal government over public lands, it also provides statutory directives for the management and protection of instream flows for the protection of the natural environment. Therefore, as long as the CWCB has acted within its authority under this provision, it has satisfied whatever public trust responsibilities it may have.
Section 37-92-102(3) gives the CWCB discretion to determine whether, and in what amount, to appropriate water to assure minimum stream flows. It provides in relevant part:
[T]he Colorado water conservation board is hereby vested with the exclusive authority, on behalf of the people of the state of *1264Colorado, to appropriate in a manner consistent with sections 5 and 6 of Article XVI of the state constitution, such waters of natural streams and lakes as the board determines may be required for minimum stream flows ... to preserve the natural environment to a reasonable degree.
§ 37-92-102(3), 15 C.R.S. (1990) (emphasis added). Furthermore,
[i]n the adjudication of water rights pursuant to this article and other applicable law, no other person or entity shall be granted a decree adjudicating a right to water or interests in water for instream flows in a stream channel between specific points or for natural surface water levels or volumes for natural lakes, for any purpose whatsoever.
Id. (emphasis added). The statute also requires that:
Before initiating a water rights filing, the board shall determine that the natural environment will be preserved to a reasonable degree by the water available for the appropriation to be made; that there is a natural environment that can be preserved to a reasonable degree with the board’s water right, if granted; and that such environment can exist without material injury to water rights.
§ 37-92-102(3)(c).
Thus, the statute gives the CWCB alone the authority to hold instream flow rights. It also requires the CWCB to make certain administrative findings before filing an application for decreed water rights.
Significantly, however, the statute does not require that the CWCB appropriate water for instream flows, but merely is a grant of authority to do so. In addition, the amount to be appropriated by the CWCB under the statute is “as the board determines may be required ... to preserve the natural environment to a reasonable degree.” Id. (emphasis added). We considered this delegation of legislative authority to the CWCB and upheld it as constitutional in Colorado River Water Conservation Dist. v. Colorado Water Conservation Bd., 197 Colo. 469, 478-80, 594 P.2d 570, 575-77 (1979). The statute thus clearly delegates authority to determine in what circumstances, and in what amount, to appropriate water for minimum stream flows to the CWCB. In the face of such a clear delegation, I would hesitate to limit by implication the discretion granted to the CWCB to determine minimum stream flows.
While the statute gives discretion to the CWCB to appropriate water for instream flows, the statute indicates that CWCB’s in-stream flow rights are to be administered within the existing prior appropriation system. The statute specifies that:
Any such appropriation shall be subject to the present uses or exchanges of water being made by other water users pursuant to appropriation or practices in existence on the date of such appropriation, whether or not previously confirmed by court order or decree.
§ 37 — 92—102(3)(b). The statute also clearly contemplates that the CWCB is subject to the same procedural requirements under the state’s water rights administration system that apply to any other water rights holder. As the statute further specifies:
The board may initiate such applications as it determines are necessary or desirable for utilizing water, water rights, or interests in water appropriated, acquired, or held by the board, including applications for changes of water rights, exchanges, or augmentation plans.
§ 37-92-102(3) (emphasis added). Applications must be submitted by rights holders and prospective rights holders to obtain “determinations of water rights” under section 37-92-302. Accordingly, aside from establishing the CWCB’s unique ability to hold instream flow rights, the statute anticipates that CWCB’s instream flow rights will be acquired and administered in the same manner as any other water right.
Under Colorado’s system of prior appropriation, adjudication by the water court is unnecessary to authorize a water rights hold*1265er to utilize less than the full decreed appropriation. Decreed water rights are frequently not exercised to the full extent of the decree. Matter of Bd. of County Comm’rs, 891 P.2d 952, 958 (Colo.1995). In fact, “[w]e have long recognized that there is read into every decree awarding priorities the implied limitation that diversions are limited to those sufficient for the purposes for which the appropriation was made, regardless of the fact that such limitation may be less than the decreed rate of diversion.” Weibert v. Rothe Bros., Inc., 200 Colo. 310, 318, 618 P.2d 1367, 1372 (1980); see also Rominiecki v. McIntyre Livestock Corp., 633 P.2d 1064, 1067 (Colo.1981). Because a decreed instream flow right is subject to an implied limitation to the minimum stream flow required to preserve the natural environment, the CWCB’s correction of its calculation of the minimum stream flow and its decision to enforce no more than that amount is fully consistent with the water court’s decree.
I recognize that, as part of its consideration of an application for recognition of a water right, the water judge
shall make such investigations as are necessary to determine whether or not the statements in the application and statements of opposition are true and to become fully advised with respect to the subject matter of the applications and statements of opposition.
§ 37-92-302(4). Nevertheless, a water decree confirms only that the “steps have been completed to effect an appropriation.” Wei-bert, 618 P.2d at 1372. It does not represent a finding on the amount of water sufficient for the purposes of the diversion. See Wei-bert, 618 P.2d at 1372 (decree not res judica-ta on the issue of historical use of water); Pulaski Irrigating Ditch Co. v. City of Trinidad, 70 Colo. 565, 568, 203 P. 681, 682 (1922) (although city diverted decreed amount, city could not sell water remaining after sewage treatment). Thus, while the water court’s decree states that the CWCB’s “statements in the application are true” and reiterates the purpose of the application and the amount of water appropriated, these findings do not represent an independent determination or even a review of the finding by the CWCB of the minimum stream flow necessary to preserve the natural environment to a reasonable degree. Contrary to the majority’s assertion, then, the CWCB did not “unilaterally modify” a lawful decree of the water court in deciding to enforce less than the full decreed instream flow right. See maj. op. at 1259.
Even if the CWCB’s decision not to enforce its full instream flow right were inconsistent with the water court’s decree in this case, there is no indication that the legislature intended for the water court to have supervisory jurisdiction over the CWCB’s administration of instream flow rights.3 The water court is neither required nor autho*1266rized by statute to make a determination of the minimum stream flow reasonably necessary to preserve the natural environment. Section 37-90-102(3) authorizes appropriation of “such waters ... as the board determines may be required for minimum stream flows,” not such waters as the water court determines may be required, (emphasis added). Nor does the water court have jurisdiction to review the CWCB’s determination of minimum stream flows. Section 37-92-203 gives the water judge
exclusive jurisdiction of water matters within the division, and no judge other than the one designated as a water judge shall act with respect to water matters in that division. Water matters shall include only those matters which this article and any other law shall specify to be heard by the water judge of the district courts.
§ 37-92-203(1) (emphasis added). Determination of “minimum stream flows ... to preserve the natural environment to a reasonable degree,” is not a matter specified by statute to be heard by the water judge and thus does not qualify as a “water matter” under the statute.
Likewise, the decision to enforce less than the decreed amount for minimum stream flow is not within the definition of any “water matters” over which the water judge has jurisdiction pursuant to article 92. The water judge has jurisdiction over applications for “determinations of water rights” under section 37-92-302. These include:
a determination of a water right or a conditional water right and the amount and priority thereof, including a determination that a conditional water right has become a water right by reason of the completion of the appropriation, a determination with respect to a change in water right, approval of a plan for augmentation, finding of reasonable diligence, approval of a proposed or existing exchange of water ..., or approval to use water outside the state ...
The water judge also must review the state engineer’s abandonment lists pursuant to section 37-92^101 and abandonment claims filed in opposition to applications for water rights. See Gardner v. State, 200 Colo. 221, 228, 614 P.2d 357, 361 (1980); § 37-92-401(6).
Of these “water matters,” none encompasses the CWCB’s determination that less than the decreed amount was necessary for minimum stream flow in this ease. The decision to use less than the full amount of a water right is not an “appropriation” 4 because it is not an application of water to a beneficial use, but is only a determination not to apply water to an already-decreed use. It is not a “change in water right”5 because a change in water right does not involve a change in quantity but a change in use of the water right. Nor is the CWCB’s decision an “abandonment” under the water judge’s jurisdiction because the water judge only need hold a hearing on an abandonment claim when asserted in opposition to a water rights determination or during a hearing once every ten years on the water engineer’s decennial abandonment list. See Gardner, 200 Colo. at 229, 614 P.2d at 362; § 37-92-401(6).
Finally, as a policy matter, even if the CWCB could be required to apply for adjudication of a reduced decree amount, documenting the relinquishment of part of the decreed amount of an instream flow right through an adjudication in the water court would not assure that CWCB appropriations *1267are “consistent with other appropriations” by providing would-be appropriators with notice of water availability.6 Availability of water for future appropriation is not based on the assumption that all absolute rights are exercised to their fullest extent, Matter of Bd. of County Comm’rs, 891 P.2d at 958, but on documented historical use, id. at 962. Without imposing similar requirements on all water rights holders, adjudication of instream flow right reductions would do little to ease the burden on future appropriators to prove water availability.
Furthermore, as part of the state water engineer’s and the division engineer’s duty to administer the waters of the state, they must prepare abandonment lists to determine and document water availability. See § 37-92-401. Under CWCB’s rules and regulations adopted in 1993, the CWCB gives written notice to the division engineer of its decision to seek enforcement of a lesser amount than set forth in the decree. Rule 10.40, 2 CCR 408-2 (1993). Accordingly, an additional hearing and decree to authorize the CWCB’s decision not to seek enforcement of its full decreed right does little to improve the efficiency of the system or to provide notice to other water users of the availability of additional water.
For the foregoing reasons, I would decline to impose implied requirements on the CWCB that would alter the degree of discretion legislatively allocated to the CWCB to determine in what circumstances, and in what amount, it should acquire and exercise instream flow rights to preserve the natural environment. I would hold that the CWCB need not seek modification of an instream flow decree in water court before deciding not to seek enforcement of its full decreed right and that CWCB is authorized by section 37-92-102(3) to enforce less than its full decreed amount for minimum stream flows.
II.
Because I would find that the CWCB’s decision to enforce less than the decreed instream flow in Snowmass Creek was not in excess of its statutory authority, I must reach the second issue on which we accepted certiorari and determine whether the CWCB’s decision was supported by substantial evidence in the record. AWW argues that the CWCB’s modified determination of minimum stream flows was not supported by substantial evidence. I disagree.
Substantial evidence ... “means such relevant evidence as a reasonable mind might accept as adequate to support a conclusion,” ... and must be enough to justify, if the trial were before a jury, a refusal to direct a verdict when the conclusion sought to be drawn from it is one of fact for the jury-
Colorado Municipal League v. Mountain States Telephone, 759 P.2d 40, 44 (Colo.1988). Therefore, where evidence is conflicting, the reviewing court may not substitute its judgment for that of the fact finder. Board of County Comm’rs v. Simmons, 177 Colo. 347, 350, 494 P.2d 85, 87 (1972); Glasmann v. Department of Revenue, 719 P.2d 1096, 1097 (Colo.App.1986).
While the evidence in this case is conflicting, under the APA standard of review, I would affirm the agency decision as supported by substantial evidence. AWW pointed to weaknesses in the analysis supporting the agency’s decision and presented independent expert witness testimony indicating that more study is necessary before relinquishing winter flow rights. However, experts from the State Department of Wildlife, the County, and Aspen Skiing Company independently confirmed that between five and seven cubic feet per second, rather than twelve cubic feet per second, would provide sufficient winter flow to preserve the natural environment. They also rebutted both AWW’s contention that the calculation error precipitating CWCB’s reconsideration of minimum stream flows along the stretch of Snowmass Creek in question did not affect the initial stream flow calculation; and *1268AWW’s contention that winter flow predictions from the County’s expert were “outside the range of accuracy.” I find that this expert testimony and supporting data constitute substantial evidence supporting the CWCB’s decision to enforce less than its decreed minimum stream flow rights in this case.
In conclusion, I would hold that (1) the CWCB acted within its statutory authority in determining that it will enforce less than its decreed instream flow right as the minimum stream flow necessary to preserve the natural environment to a reasonable extent, and (2) this decision was supported by substantial evidence in the record. Accordingly, I would affirm the judgment of the district court.
VOLLACK, C.J., joins in this dissent.
. AWW also challenges the CWCB’s decision on due process grounds. It argues that “the people are the true beneficiaries of the right and, as such, cannot be deprived of their property interest without due process.” This argument is without merit.
*1262Due process protections do not attach to undifferentiated public property interests. "When governmental action affects more than a few individuals, concerns beyond economy, efficiency, and expedition tip the balance against finding that due process attaches. We may expect that as the sweep of governmental action broadens, so too does the power of the affected group to protect its interests outside rigid constitutionally imposed procedures.” O’Bannon v. Town Court Nursing Center, 447 U.S. 773, 799-800, 100 S.Ct. 2467, 2483, 65 L.Ed.2d 506 (1980) (Blackmun, J., concurring). Accordingly, when as here CWCB’s decisions affect the public as a whole, no additional constitutional protections apply.
I note also that the public has been afforded considerable process in this case nevertheless. Based on investigations on Snowmass Creek by the Division of Wildlife, CWCB became aware that the minimum stream flow appropriation might be too high at some times of the year and too low at others. CWCB gave public notice that the matter would be considered at its March, 1992, meeting. At that meeting, CWCB decided to reconsider the instream flow right. The board received public comment at meetings in May, July and September which included testimony from biological consultants from the County, Aspen Skiing Company and AWW, and extensive technical reports. It did not take final action until its September 15, 1992, meeting.
Furthermore, because the CWCB's decision is not subject to constitutional scrutiny does not mean it is not subject to review. CWCB’s decisions are subject to procedural requirements and judicial review under the APA, as discussed in the text of this dissent. I would find that public interests represented by AWW thus have received all of the process these interests are due without additional review by the water court.
. The majority apparently buttresses this assertion by distinguishing CWCB from other water users who may "appropriate water for beneficial uses much broader than the authority by which the Board acts.” Maj. op. at 1259 n. 14. Specifically, the majority asserts that under the statutory definition of beneficial use, § 37-92-103(4), "the Board's authority is limited by statute to preserving the natural environment to a reasonable degree” while others may appropriate "that amount of water that is reasonable and appropriate ... to accomplish ... the purpose for which the appropriation is lawfully made." Maj. op. at 1259 n. 14.
However, CWCB's authority to appropriate water is not limited to preservation of the environment pursuant to the statutory definition of beneficial use, section 37-92-103(4), as the majority asserts. The broader mandate of the CWCB is to "aid[] in the protection and development of the waters of the state ... for the benefit of the present and future inhabitants of the state.” § 37-60-102 (emphasis added). To this end, since 1971, the CWCB has the authority to file applications and take "all action necessary” to acquire or perfect water rights for the full range of projects sponsored by the CWCB. § 37-60-106(l)(m) & (l)(n); see Ch. 379, sec. 1, § 149-1-11, 1971 Colo.Sess.Laws 1343.
Accordingly, and contrary to the majority’s assertion, in 1973, when the legislature authorized *1263CWCB to appropriate water for minimum stream flows and included minimum stream flows in the definition of beneficial use, it did not limit the authority of the CWCB. See Ch. 442, sec. 2, § 148-21-2, 1973 Colo.Sess.Laws 1521-22. Pri- or to 1973, the CWCB had been subject to the same definition of "beneficial use" as all other appropriators. In giving CWCB authority to appropriate water for the preservation of the natural environment, the legislature thus expanded the authority of CWCB.
. The majority cites § 37-92-102(3)(c.5) as indicating "the General Assembly's intent that the Board must proceed through the water court to change a decreed conditional water right.” Maj. op. at 1260 n. 16. Although I first note that the cited section has no application to the case before us because the section applies only to CWCB’s acquisition of conditional water rights in the Yampa river basin, § 37 — 92—102(3)(c.5)(I), I agree with the majority's general point.
A conditional water right is "a right to perfect a water right with a certain priority upon the completion with reasonable diligence of the appropriation upon which such water right is to be based.” § 37-92-103(6). It follows that the CWCB cannot obtain a conditional instream flow water right by initial appropriation because no diversion of water is necessary to complete the appropriation of instream flows. CWCB can only obtain such a right from another rights-holder by some form of contractual agreement. See § 37-92-102(3); § 37-92-102(3)(c.5)(III) (CWCB must demonstrate that the acquisition of conditional water rights will provide benefits that would not be available through initial appropriation by the CWCB). Since the CWCB is the only entity authorized to hold water rights for in-stream flows, applying conditional rights to maintain instream flows necessarily involves a “change of water right” because it changes the use of the water. See § 37-92-103(5). Application to the water court is required for a "change of water right” under § 37-92-302(l)(a).
However, as this discussion illustrates, both a “change in water right” and a "conditional water right” are terms of art under the statute, and neither is involved in this case. § 37-92-102(3)(c.5) does not support the proposition that "modifications of an appropriation” such as the one at issue here, are within the jurisdiction of the water court, as the majority holds. Maj. op. at 1260; see id. at 1257-58 n. 11.
. "Appropriation" means "the application of a specified portion of the waters of the state to a beneficial use pursuant to the procedures prescribed by law....” § 37-92-103(3)(a).
. "Change in water right” means "a change in the type, place, or time of use, a change in the point of diversion, a change from alternate or supplemental points of diversion to a fixed point of diversion, a change in the means of diversion, a change in the place of storage, a change from direct application to storage and subsequent application, a change from storage and subsequent application to direct application, a change from a fixed place of storage to alternate places of storage, a change from alternate fixed place of storage to alternate places of storage, a change from alternate places of storage to a fixed place of storage, or any combination of such changes....” § 37-92-103(5).
. Prior appropriators would be unaffected by the CWCB’s instream flow rights because their rights are of higher priority and can be enforced against the CWCB. See City of Colorado Springs v. Bender, 148 Colo. 458, 463-64, 366 P.2d 552, 555-56 (1961).