author: Justice MARTINEZ

text:
    CONCERNING the APPLICATION FOR PLAN FOR AUGMENTATION OF the CITY AND COUNTY OF DENVER, acting by and through its BOARD OF WATER COMMISSIONERS, The City of Thornton, Objector Appellant, v. The City and County of Denver, acting by and through its Board of Water Commissioners, Applicant-Appellee, and Centennial Water and Sanitation District, the City of Aurora, the City of Engle-wood, and Henrylyn Irrigation District, Objector-Appellees, and Richard Stenzel, Division Engineer, Water Division 1, Appellee pursuant to C.A.R. 1(e).
    No. 008A302.
    Supreme Court of Colorado.
    Feb. 25, 2002.
    As Modified on Denial of Rehearing April 29, 2002.

      White & Jankowski, LLP, Michael D. White, William A. Hillhouse, II, Austin C. Hamre, David C. Taussig, Sarah A. Klahn, Denver, CO, Attorneys for Objector-Appellant.
    Patricia L. Wells, Michael L. Walker, Casey 8. Funk, Kristi K. Riegle, Denver, CO, Attorneys for Applicant-Appellee.
    Moses, Wittemyer, Harrison, & Woodruff, P.C., Veronica A. Sperling, Boulder, CO, Attorneys for Objector-Centennial Water and Sanitation District.
    Chrisman, Bynum & Johnson, P.C., David G. Hill, Jack M. Graves, Kristin M. Berdan, Boulder, CO, Attorneys for Objector-Appel-lee City of Englewood.
    Friedlob Sanderson Paulson & Tourtillott, LLC, Brian M. Nazarenus, William B. Tour-tillott, Denver, CO, Attorneys for Amici Curiae City of Loveland, Public Service Company of Colorado, d/b/a Keel Energy, Climax Molybdenum Company, and the City of Fountain.
   Justice MARTINEZ

delivered the Opinion of the Court.

The City of Thornton ("Thornton") appeals the order of the District Court for Water Division No. 1 ("water court") denying Thornton's petition to extend the period of retained jurisdiction, see § 37-92-804(6), 10 C.R.S. (2001), agreed to by Thornton and the City and County of Denver, acting by and through its Board of Water Commissioners ("Denver"), in a stipulated decree later approved by the water court. Thornton filed a timely petition seeking to invoke the retained Jurisdiction provision. The petition requested that the water court reconsider its finding of non-injury to Thornton and other senior water appropriators in light of the actual operation of Denver's Augmentation Plan. Specifically, Thornton alleged that the effluent discharged from the Bi-City Wastewa-ter Treatment Plant ("the Bi-City plant"), as a substitute water supply under Denver's Augmentation Plan, was unsuitable for Thornton's use as a municipal water supply. The water court denied the petition without a hearing. We conclude that the water court had an obligation to reconsider the question of injury to Thornton and other senior appropriators. Therefore, we reverse the water court's decision not to hold a hearing to address Thornton's alleged injury from the operation of Denver's Augmentation Plan, or in the alternative, to extend the period of retained jurisdiction pending resolution of common water quality issues in the Denver exchange case that the water court currently has before it.

I. Facts and Procedural History

In April 1991, Denver petitioned for an augmentation plan to allow for out-of-priority diversions from the South Platte River for the irrigation of the Overland Park Golf Course. Denver's Proposed Augmentation Plan provided for a substitute supply using effluent from the Bi-City plant. Thornton, the Centennial Water and Sanitation District, the City of Englewood, Henrylyn Irrigation District, and the City of Aurora filed timely Statements of Opposition. Because Thornton diverts water from the South Platte River downstream from the Bi-City plant for its own water supply system, Thornton alleged potential water quality injuries. In particular, Thornton expressed concern regarding the effect of Denver's Proposed Augmentation Plan on the concentration of pollutants in the river at Thornton's point of diversion. Thornton chose not to proceed to trial, at which Denver would have had to prove the absence of injury resulting from Denver's Proposed Augmentation Plan. Instead, on March 11, 1998, Thornton stipulated to the entry of a decree granting Denver's application for an augmentation plan, provided that the terms of the decree were "not less restrictive" than the attached proposed decree. At that time, Thornton agreed to the substitution of Platte River water for Bi-City effluent and agreed the effluent adequately met its lawful requirements so that Denver's Augmentation Plan would not injuriously affect Thornton's vested water rights.

On May 24, 1993, the water court approved the terms of Denver's Augmentation Plan. At the request of both parties and pursuant to section 37-92-804(6), the water court retained jurisdiction over the case for seven (7) years. See § 37-92-304(6). On May 28, 2000, Thornton filed a timely Petition Invoking Retained Jurisdiction. Thornton claimed that changes in the operation of the Bi-City plant since 1993 have increased the levels of phosphorous, nitrate, nitrite, harmful types of dissolved organic carbon and microbiological contaminates in the Bi-City effluent, making the water supply unsuitable for Thornton's normal use as a municipal water supply. The petition requested that the water court extend the period of retained jurisdiction in this case (1CW28) until the resolution of another ongoing dispute between Denver and Thornton (the Denver exchange case-96CW145). The Denver exchange ease concerns Thornton's alleged injury from Denver's use of Bi-City effluent and other water sources as a substitute supply. Thornton argues the current case and the Denver exchange case present parallel allegations of injury and common factual issues, including the suitability of Bi-City effluent as a substitute supply for a downstream user who is a municipal water supplier. Specifically, the Denver exchange case concerns "the health effects of pollutants contained in Bi-City effluent."

Similarly, Thornton's Petition to Invoke Retained Jurisdiction contended:

Since the entry of the decree in this case in 1993, the injury to Thornton from the operation of Denver's Overland Park augmentation plan, and particularly the use of Bi-City effluent, has become apparent. For example, the use of Bi-City effluent has caused injurious water quality effects that include, but are not limited to, increasing concentrations of phosphorous, nitrate and nitrite, [and] harmful types of dissolved organic carbon and microbiological contaminates.

R. at 104-05. Thornton continued:

The nature and extent of Thornton's injury from Denver's use of Bi-City effluent was not fully known when the decree was entered in this case.... [HJlowever, the health effects of pollutants contained in Bi-City effluent have come to be better understood, and the injury produced by the use of Bi-City effluent as a substitute supply has become a central issue in the ongoing litigation between Denver and Thornton in Case No. 96CW145 (the Denver exchange case).... [There has been substantial evidence that Denver's use of Bi-City effluent as a substitute supply injures Thornton. Certainly the nonoceur-rence of injury has not been conclusively established.

R. at 105. Thornton therefore requested that the water court hold proceedings on the necessity for modification of Denver's Augmentation Plan, or alternatively, extend the period of retained jurisdiction and defer the question of injury until the resolution of common factual questions raised by the Denver exchange case.

The water court refused to extend the period of retained jurisdiction for the resolution of the Denver exchange case, noting that Thornton had stipulated to Denver's use of Bi-City effluent as part of Denver's Augmentation Plan. R. at 189. The water court found that better understanding of the detrimental water quality effects of wastewater treatment plant effluent was not the type of injury the general assembly intended the retained jurisdiction statute to address. R. at 189. The court stated:

To allow jurisdiction to be retained, pending the factual findings of a later case, would frustrate the final judgments of the Water Court, as well as the justifiable reliance of the parties on the finality of the prior proceedings. If new light has been shed on the injurious effects of effluent upon other users, the proper forum in which to address this potential injury is to oppose subsequent applications that implicate such injury.

Id. The water court therefore denied Thornton's motion to extend the period of retained jurisdiction. Id.

II. Legal Background

Although this case concerns the retained jurisdiction provision of section 37-92-304(6), a discussion of the prior appropriation doe-trine and the role of augmentation plans is necessary to understand the general assembly's intent that the retained jurisdiction provision operate as a test period of the water court's initial prediction of non-injury. Accordingly, we first discuss the role of augmentation plans in the state's policy of maximum utilization of water. Second, we explain the scope and purpose of the retained Jurisdiction provision. Third, we discuss the relationship between Colorado caselaw regarding water quality, the Water Quality Control Act ("WQCA"), the Colorado Constitution, and the Water Right Determination and Administration Act ("WRDAA"). Finally, we apply our analysis to the facts of this case.

After analyzing this case as described, we conclude that the water court erroneously held that the retained jurisdiction provision did not permit the court to revisit its initial determination of non-injury to Thornton under Denver's Augmentation Plan. The retained jurisdiction period functions as a test period of the water court's prediction of non-injury to senior appropriators from an augmentation plan. Farmers Res. & Irr. Co. v. Consol. Mut. Water Co., 38 P.3d 799, 806 (Colo.2001). As explained below, retained jurisdiction should be invoked where the operational experience of an augmentation plan demonstrates that substituted water is not "of a quality ... to meet the requirements for which the water of the senior appropriator has normally been used." § 87-92-305(5), 10 C.R.S. (2001). In spite of the water court's prediction that Denver's Augmentation Plan would not injuriously af-feet Thornton, the plan's actual operation may not provide replacement water suitable for Thornton's normal use of South Platte water at its point of diversion in comparison to the quality of water it received before Denver's Augmentation Plan was approved. Under such cireumstances, the water court has an obligation to invoke retained jurisdiction to prevent injury to senior appropriators like Thornton. Otherwise, the water court would be unable to ensure the quality of the water supply as required by section 37-92-3058). In the interest of preserving the finality of water appropriations, the water court's ability to revisit injury determinations is limited to the period of retained jurisdiction, or its extension by the court.

A. Augmentation Plans

The Colorado Constitution makes the unappropriated "water of every natural stream" within the state the "property of the public" for the "use of the people of the state." Colo. Const. art. XVI, § 5. Therefore, Colorado water law is governed by the doctrine of prior appropriation. See Colo. Const. art. XVI, § 6; Coffin v. Left Hand Ditch Co., 6 Colo. 443, 447 (1882). Generally, the first appropriator of water for a beneficial use has a prior right to the water to the extent of such appropriation. Coffin, 6 Colo. at 447. Thus, much of the value of a water right lies in its priority. See Gregory J. Hobbs, Jr., Symposium: Colorado's 1969 Adjudication and Administration Act: Settling In, 3 U. Denv. Water L.Rev. 1, 7-12 (1999).

The WRDAA provides for the adjudication of water rights changes, exchanges, and augmentation plans. Through such ' adjudications, the WRDAA seeks to allow new water users to operate consistently with the administration of decreed water rights under the prior appropriation system. Farmers Res. & Irr. Co., 33 P.3d at 806; § 37-92-302, 10 CRS. (2001). Thus, the WRDAA furthers the state's policy 'of efficiently managing, administering, and optimizing water use for the operation of as many decreed uses as there is an available water supply: Farmers Res. & Irr. Co., 33 P.3d at 806. Water right changes, exchanges, and augmentation plans allow diversions as long as the prior appropriators' rights are unharmed. § 37-92-305(8), (5), § 37-80-120; §37-83-104, 10 C.R.S. (2001); James N. Corbridge, Jr. & Teresa A. Rice, Vramesh's Colorado Water Low Revised Ed. 142-144 (1999) [hereinafter Vranmesh's ]. Because this case concerns Denver's Augmentation Plan, we limit our discussion to augmentation plans.

When no unappropriated water is available, augmentation plans permit junior water right holders to divert water out-of-priority while ensuring the protection of senior water right holders. Farmers Res. & Irr. Co., 33 P.3d at 806 (citing Danielson v. Castle Meadows, Inc., 791 P.2d 1106, 1112 (Colo.1990). An augmentation plan is defined as:

A detailed program ... to increase the supply of water available for beneficial use in a division or portion thereof by the development of new or alternate means or points of diversion, by pooling of water resources, by water exchange projects, by providing substitute supplies of water, by the development of new sources of water, or by any other appropriate means....

§ 37-92-103(9), 10 C.RS. (2001); City of Florence v. Bd. of Waterworks of Pueblo, 793 P.2d 148, 151 (Colo.1990). Junior appropriators typically provide an augmented water supply to offset their out-of-priority deple-tions so that holders of decreed water rights can enjoy the quantity of supply that would be available to them absent those depletions. Farmers Res. & Irr. Co., 38 P.3d at 806.

Section 37-92-805(8) expressly requires augmentation plans be made with due regard for the rights of other appropriators of the same water source. A water court proceeding for approval of an augmentation plan is mandatory and can be approved only if there is "no-injurious effect" to a vested water right. Danielson, 791 P.2d at 1112; Vranesh's, supra at 144; see also § 37-92-305(5). Where injury is likely to occur, terms and conditions may be included in decrees for augmentation plans to prevent injury. § 37-92-305(8), (4). If the substituted water is "of a quantity and quality so as to meet the requirements for which the water of the senior appropriator has normally been used," the proposed substitution must be accepted. § 37-92-305(5).

This court has recognized that full augmentation requires replacement of water depletions in the amount, location, and time necessary to protect vested rights. Farmers Res. & Irr. Co., 33 P.3d at 806. 'The proponent of an augmentation plan has the burden of establishing the absence of injury resulting from the out-of-priority diversion of water. $ 37-92-304(8), 10 C.R.S. (2001); Danielson, 791 P.2d at 1115. An objector to an augmentation plan need not show an injury to a specific water right; injury to senior appropriators in general is enough. Danielson, 791 P.2d at 1114. Where a statement of opposition is filed, the applicant provides the water court with a proposed ruling or decree designed to prevent such injurious effect. § 37-92-305(8); City of Thornton v. Clear Creek Water Users Alliance, 859 P.2d 1348, 1358 (Colo.1998). If the water court finds that injury will occur to vested rights, it must impose terms and conditions on the augmentation plan to remedy such injury. Danielson, 791 P.2d at 1112.

B. Retained Jurisdiction

Because the actual effects of an augmentation plan cannot always be accurately predicted, the general assembly has provided for a period of retained jurisdiction in which the water court may reconsider possible injury to senior appropriators. Section 87-92-304(6) provides:

Any decision of the water judge ... dealing with a change of water right or a plan for augmentation shall include the condition that the approval of such change or plan shall be subject to reconsideration by the water judge on the question of injury to the vested rights of others for such period after entry of such decision as is necessary or desirable to preclude or remedy such injury. Such condition setting forth the period allowed for reconsideration shall be determined by the water judge after making specific findings and conclusions including, when applicable, the historic use to which water rights involved were put, if any, and the proposed future use of the water rights involved. The water judge shall specify his determination as to such period in his decision, but the period may be extended upon further decision by the water judge that the nonoceur-rence of injury shall not have been conclusively established.

§ 37-92-304(6); see Farmers Res. & Irr. Co., 33 P.3d at 805 (holding that a water court's historic use determinations may not be reviewed under the retained jurisdiction provision); Clear Creek Water Users Alliance, 859 P.2d at 1358 (stating that water court retained jurisdiction to allow for reconsideration of injury determination where application for change of water rights did not specify a diversion point).

Section 37-92-804(6) reflects the two stages of the water court's future injury analysis. Farmers Res. & Irr. Co., 33 P.3d at 811. The first stage is based on predicting the future effects of an augmentation plan. Id. The second stage is based on operational experience of the augmentation plan. Id. Retained jurisdiction provides the water court and water users with the flexibility to implement programs that maximize the beneficial use of water while protecting the vested rights of senior water appropriators. See City of Florence, 793 P.2d at 157.

Retained jurisdiction protects the rights of parties opposed to an augmentation plan because it allows the water court to reconsider the question of injury until the nonoccurrence of injury to the objecting party's water rights is conclusively established. Clear Creek Water Users Alliance, 859 P.2d at 1360. The water court sets the length of retained jurisdiction at the period of time it finds "necessary or desirable to preclude or remedy such injury" based on the evidence. § 37-92-304(6); Farmer's Res. & Irr. Co., 33 P.3d at 806. The water court may later extend the period of retained jurisdiction "upon further decision" that the "nonoceur-rence of injury shall not have been conclusively established." Farmers Res. & Irr. Co., 33 P.3d at 806. However, the judgment and decree remain "appealable upon entry, notwithstanding conditions subjecting the decisions to reconsideration on the question of injury to the vested rights of others." § 37-92-304(6); Farmers Res. & Irr. Co., 33 P.3d at 806.

Because the water court has already determined non-injury at the time of entry of the decree, the water court may require a party seeking to invoke the court's retained jurisdiction to make a prima facie showing of injury from the augmentation plan's operation. Farmers Res. & Irr. Co., 33 P.3d at 811; Danielson, 791 P.2d at 1115. Upon such a showing, the burden of showing non-injury shifts to the decree-holder. Farmers Res. & Irr. Co., 33 P.3d at 811-12. This injury analysis has traditionally focused on the time, amount, and location of return flows of surface water and groundwater. Id. at 807 n. 6.

Once a party demonstrates injury to its water rights, the water court must require additional or modified protective conditions to prevent injury. Id. at 812. The water court may also extend the period of retained jurisdiction as long as necessary to ascertain non-injury from operation of the augmentation plan. Id. The water court abuses 'its discretion by refusing to require additional or modified protective conditions to prevent injury, or by refusing to extend the period of retained jurisdiction to ascertain the non-occurrence of injury, once the person seeking a change has met the initial burden of establishing injury under the statute and the decree-holder has not met the burden of demonstrating non-injury. Id. at 811.

The water court may reopen the inquiry into protective conditions upon sufficient showing that other water rights holders experienced water shortages resulting from failure to implement the protective conditions or because protective conditions adopted in the judgment and decree did not sufficiently protect against injury. Id. at 810. Alternatively, the water court may extend the period of retained jurisdiction if it finds the nonoccurrence of injury has not been conclusively established. Id.

The focus of retained jurisdiction is not upon changed cireumstances or unantic-pated injury. Id. Instead, the proper focus of retained jurisdiction is the injurious effects of the operation of the augmentation plan. Id. The statute addresses the water court's role in predicting the potential injurious effect of the augmentation plan and the measures needed to prevent injury once the change takes operational effect upon the stream system. Id.

Our decision in City of Thornton v. Clear Creek Water Users Alliance, 859 P.2d 1348 (Colo.1993), demonstrates the use of retained jurisdiction where some uncertainty exists about whether a proposed water decree for an augmentation plan will produce injury to water appropriators. The water court may anticipate better information about potential injury once the plan becomes operational. Under such cireumstances, retained jurisdiction temporarily preserves the question of injury notwithstanding the water court's initial determination of non-injury. Without this retained jurisdiction, the water court's responsibility of ensuring the suitability of replacement water utilized in an augmentation plan could not be met, particularly where the augmentation plan's operation proves the water court's prediction of non-injury incorrect.

Clear Creek Water Users Alliance used retained jurisdiction to address possible injury to water quantity, an issue that lies within the water court's traditional seope of authority. Clear Creek Water Users Alliance, 859 P.2d at 1348. Water quantity issues typically include any discrepancies in the time, amount, and location of return flows of water. Clear Creek Water Users Alliance concerned Clear Creek Water Users Alliance's ("CCWUA") application for a change of a conditional water right involving five alternative storage sites. Thornton opposed the application, arguing that the city would be injured by the proposed decree.

The water court approved the change despite CCWUA's failure to designate a specific storage size or location, and the corresponding uncertainty in possible injury to Thornton as a result of the change. Acknowledging the difficulty in determining any injury to Thornton or other senior appropriators in the absence of specifics regarding the storage gite, the water court retained jurisdiction over the matter for five years until CCWUA could be more specific about the change. Id. at 1859.

Thornton objected to both the approval of the plan and the water court's calculation of retained jurisdiction. Id. at 1360. Specifically, Thornton argued that the five-year period of retained jurisdiction should not begin to run until "the full and actual operation of the water right as changed" had begun. Id. The city maintained that only after the reservoirs were built and used would the water court be equipped with the operational facts necessary to examine the diversion, use and return flows, and determine whether water users like Thornton would be injured by the decree. Id. Thus, Thornton contended that the water court had erroneously granted the decree.

We upheld the water court's approval of CCWUA's application for a change in the association's conditional right to store water and the water court's use of retained jurisdiction to ensure that Thornton and other senior water users were in fact uninjured by the decree onee CCWUA chose a specific storage site. Id. We first noted that the law did not require an applicant to specify a diversion point. Id. We next noted that the water court had found no showing of injury to Thornton at the entry of the decree. Id. Therefore, we held that the water court appropriately approved the plan. Id. The retained jurisdiction provision began to run from the time of the decree and not from the time the change in the conditional water right became operational. Id. However, the court noted that the water court could extend the five-year period of retained jurisdiction if it found that non-injury to Thornton and other senior water appropriators had not been conclusively established once the change of conditional water right became operational. Id.

III. Retained Jurisdiction and Water Quality

Denver seeks to distinguish Clear Creek Water Users Alliance from the present case on the basis that Clear Creek Water Users Alliance concerned the use of retained jurisdiction in relation to water quantity issues, which unquestionably lie within the water court's jurisdiction, and not water quality issues. Denver rests its distinction with the fact that the WQCA grants the Department of Health and the nine-member Water Quality Control Commission ("WQCC") authority over state water quality and the prevention of water pollution. See §§ 25-8-103, -201, - 202, 8 C.R.S. (2001). In order to assess the merits of Denver's distinction between water quantity and water quality with respect to retained jurisdiction, it is necessary to understand the relationship between Colorado caselaw regarding water quality, the WQCA, the Colorado Constitution, and the WRDAA.

A. Water Quality Caselaw

It is true, as Denver argues, that Colorado water law has historically focused on water quantity issues so that the law regarding water quality is not well developed. See Vramesh's, supra at 471. Notwithstanding the lack of focus on water quality issues, we have protected water quality to the extent necessary to preserve the water's suitability for the uses of appropriators. See Slide Mines, Inc. v. Left Hand Ditch Co., 102 Colo. 69, 73, 77 P.2d 125, 127 (1938) (finding that extraneous matter introduced into a stream by farmers that did not unfavorably affect the use of the water they were entitled to make but was beneficial to it did not constitute pollution in a legal sense). Upon rehearing its original decision in Wilmore v. Chain O'Mines, Inc., 96 Colo. 819, 44 P.2d 1024 (1934), this court defined "pollution" as

an impairment, with attendant injury, to the use of water that [downstream appropriators] are entitled to make. Unless the introduction of extraneous matter so unfavorably affects such use, the condition cere-ated is short of pollution. In reality, the thing forbidden is injury.

Thus, Chain O'Mines established a common law theory based on the prior appropriation doctrine that prohibits the discharge of contaminates into streams where doing so makes the water unsuitable for an appropriator's normal use of the water. In addition, we concluded that injury occurred where the Game and Fish Commission's diversion of water through a fish hatchery rendered the water unfit for Farmers Irrigation Company's normal irrigation and domestic use. See Game & Fish Comm'n v. Farmers Irr. Co., 162 Colo. 301, 426 P.2d 562 (1967); Farmers Irr. Co. v. Game & Fish Comm'n, 149 Colo. 318, 369 P.2d 557 (1962).

B. Water Quality Control Act

Current statutory law delegates most authority over water quality issues to the WQCC. The general assembly enacted the WQCA, §§ 25-8-101 to ~7083, 8 C.R.S. (2001), in response to the federal Clean Water Act. The purpose of the WQCA is

to prevent injury to beneficial uses made of state waters, to maximize the beneficial uses of water, and to develop water to which Colorado and its citizens are entitled, and, within this context, to achieve the maximum practical degree of water quality in the waters of the state consistent with the welfare of the state.

§ 25-8-108, 8 C.R.S. (2001). Thus, the Act sought to provide the maximum protection for water quality possible without threatening the prior appropriation system and the state's policy of maximum beneficial use of the water. The general assembly also sought

to conserve state waters and to protect, maintain, and improve, where necessary and reasonable, the quality [of state waters] for public water supplies, for protection and propagation of wildlife and aquatic life, for domestic, agricultural, industrial, and recreational uses, and for other beneficial uses, taking into consideration the requirements of such uses; to provide that no pollutant be released into any state waters without first receiving the treatment or other corrective action necessary to reasonably protect the legitimate and beneficial uses of such waters; [and] to provide for the prevention, abatement, and control of new or existing water pollution.

Id. Thus, the WQCA expresses an intent to prevent water pollution and specifically refers to the need to protect the beneficial use of water in a variety of different contexts.

The state's purpose of protecting water quality is served by a nine-member WQCC authorized by the WQCA to develop and maintain a comprehensive program for the prevention, control, and abatement of water pollution, and water quality protection. §§ 25-8-201-, -202; Vranesh's, supra at 476. Although the WQCA gives the WQCC general authority over water quality issues, the WQCA is not intended to interfere with the water court's role in adjudicating water rights administered by the State Engineer. Section 25-8-104(1) of the WQCA explicitly provides that:

No provision of this article shall be interpreted so as to supercede, abrogate, or impair rights to divert water and to apply water to beneficial uses in accordance with sections 5 and 6 of article XVI of the constitution of the state of Colorado, compacts entered into by the state of Colorado, or the provisions of articles 80 to 98 of title 37, C.R.S8., or Colorado court determinations with respect to the determination and administration of water rights.

§ 25-8-104(1) (emphasis added). We read these provisions of the WCQA to allow the WCQA to work within the context of the prior appropriation system. See City of Thornton v. Bijou Irr. Co., 926 P.2d 1, 66 (Colo.1996) (holding that the legislature clearly intended that authority over water quality not be exercised in a manner that significantly compromises the appropriative rights of present or future water users). Because the WQCA explicitly provides that it is not to interfere with the water court's role in adjudicating water rights, we conclude that the general assembly did not intend the WQCA to interfere with the water court's ability to protect senior water appropriators as set forth in sections 37-92-304(6) and 37-92-305(5).

The WQCA explicitly preserves the water court's authority over the question of injury to senior appropriators and the appropriate remedies for such injuries. Section 25-8-104 also provides:

Nothing in this article shall be construed, enforced, or applied so as to cause or result in material injury to water rights. The general assembly recognizes that this article may lead to dischargers choosing consumptive types of treatment techniques in order to meet water quality control requirements. - Under such cireumstances, the discharger must comply with all of the applicable provisions of articles 80 to 98 of title 37, C.R.S., and shall be obligated to remedy any material injury to water rights to the extent required under the provisions of articles 80 to 98 of title 37, C.R.S. The question of whether such material injury to water rights exists and the remedy therefor shall be determined by the water court.

§ 25-8-104(1) (emphasis added). We conclude from this provision that the water court's role in assessing injury and preserving appropriators' water rights in augmentation plan proceedings remains intact despite the WQCC's role in protecting the quality of the state's waters.

C. Water Court's Role Under WRDAA

The WRDAA explicitly requires the water court to consider water quality issues in the case of an augmentation plan in which water is being actively substituted into a stream for the use of other appropriators. See § 37-92-305(5); Bijou Irr. Co., 926 P.2d at 66. The substituted water must be of a quality and continuity to meet the requirements for which the water of the senior appropriator has normally been used. § 37-92-805(5).

The WRDAA provides that the water court must approve an augmentation plan if it will not injuriously affect the owner of or persons entitled to use water under a vested water right or a decreed conditional water right. § 37-92-305(8).

Despite the general assembly's assignment of water quality issues to the WQCC, the language of the WQCA clearly expresses a legislative intent for water quality issues to remain within the purview of the water court as set forth in the WRDAA. See § 25-8-104(1). Section 25-8-104(1) explicitly states that the water court retains authority over the question of whether material injury to water rights exists and the remedy for such injury. Id. Injury occurs under the WRDAA where the water provided by an augmentation plan is not of a quality and quanity so as to meet the requirements for which the water of the senior appropriator has normally been used. See § 87-92-305(8), (5). The WRDAA and the WQCA therefore preserve the common law standard that the introduction of pollutants into a water supply constitutes injury to senior appropriators if the water is no longer suitable for the senior appropriator's normal use because of the substitute supply. See § 25-8-104(1).

This court has recognized that Colorado's division of responsibility over water matters between the water courts and the WQCA limits the ability of both the water court and water quality control agencies to address certain water quality control issues. Bijou Irr. Co., 926 P.2d at 66. Nevertheless, the WQCA and the WRDAA guarantee the right of senior appropriators to a substitute water supply suitable for their normal use of the water prior to the implementation of the augmentation plan, despite the role of the WQCC over general water quality issues. § 25-8-104(1); 87-92-305(5).

IV. Application

Thornton argues that the water court should have held proceedings on the need to modify Denver's Augmentation Plan, or in the alternative, extended the seven-year period of retained jurisdiction until the nature and extent of Thornton's injury from the use of Bi-City effluent could be determined in the Denver exchange case. Thornton alleges injury because the quality of the effluent actually produced by the Bi-City plant as a substitute supply makes the water unsuitable for Thornton's normal use of the water as a municipal water supply. Denver seeks to distinguish between our use of retained jurisdiction to address uncertainty in the water court's initial prediction of non-injury with regard to water quantity issues like the time, amount, and location of return flows, and a prediction of non-injury with regard to water quality. Denver bases its distinction on the existence of the WQCA and the WQCC's general authority over water quality and water pollution prevention.

Here, Thornton filed a petition within the seven-year period of retained jurisdiction provided by the decree. The petition alleged that "the use of Bi-City effluent has caused injurious water quality effects that include . increasing concentrations of phosphorous, nitrate and nitrite, harmful types of dissolved organic carbon, and microbiological contaminates." R. at 104. The petition continued, "there has been substantial evidence that Denver's use of Bi-City effluent as a substitute supply injures Thornton." R at 105. Thornton argued that resolution of the pending Denver exchange case involving water quality issues might reveal the terms and conditions necessary to prevent injury to Thornton in this case, at which time the water court could set any necessary further proceedings. Thornton requested that the water court extend the "period of retained jurisdiction until the issue of injury to Thornton from Denver's use of Bi-City effluent as a substitute supply" could be resolved. Id.

In denying the petition, the water court focused on the following language in the petition: "The nature and extent of Thornton's injury from Denver's use of Bi-City effluent was not fully known when the decree was entered in this case ... Subsequently, however, the health effects of pollutants contained in Bi-City effluent have come to be better understood." Id. The court concluded that better understanding of the detrimental water quality effects of wastewater treatment plant effluent was not the type of injury the retained jurisdiction statute was designed to address. R. at 189. In denying the petition, the water court overlooked Thornton's allegations of the injurious water quality effects of using Bi-City effluent that allegedly contained increased levels of phosphorous, nitrate, nitrite, dissolved organic carbon, and microbiological contaminates.

The water court also misinterpreted the scope of Thornton's stipulation to the use of Bi-City effluent as part of Denver's Augmentation Plan. After initially objecting to the plan, Thornton stipulated that the "replacement water provided for under [Denver's] Plan for Augmentation [was] adequate to meet the lawful requirements of a senior diverter at the time and location and to the extent the senior would be deprived of his lawful entitlement by the Applicant's diversion." R. at 115-116. Thornton further agreed that Denver's Proposed Augmentation Plan "would not injuriously affect the owners of or persons entitled to use water under a vested water right or decreed conditional water right." R. at 115-116, 126-127.

The augmentation plan approved by the water court provided: R. at 126. The language of the water court's decree tracks section 37-92-805(5), which governs the standard for suitability of replacement water utilized for augmentation plans. This language is more specific, but has essentially the same meaning as the language used in the proposed augmentation plan Thornton submitted with its stipulation. Accordingly, Thornton's stipulation concedes nothing more than what the water court would have determined in the first stage of the injury analysis at the time of the initial decree. See § 37-92-305(8) (requiring that a plan not injuriously affect persons entitled to use water under a vested water right). Therefore, it does not foreclose consideration of whether injury resulted from the operation of Denver's Augmentation Plan.

The replacement water provided for under this Plan for Augmentation is of a quality and quantity so as to meet the requirements for which water of the senior appropriator has normally been used, and such replacement water shall be accepted by the senior appropriator in substitution for water derived by the exercise of his decreed rights.

The legislature provided for both a determination of non-injury to senior appropriators at the time of the initial decree approving an augmentation plan, and a period of retained jurisdiction during which the water court could reconsider its initial determination of non-injury in light of the actual operation of the plan. See § 37-92-8305; § 37-92-804(6). Although Thornton initially agreed that it would not be injured by the use of Bi-City effluent in Denver's Augmentation Plan, the stipulation governed only the water court's initial determination of non-injury to Thornton during the first stage of the injury analysis. The second stage of the injury analysis occurs later, onee an augmentation plan becomes operational. The question of operational injury remained open for reconsideration at the second stage of the injury analysis under the retained jurisdiction provision. See 37-92-304(6); Farmers Res. & Irr. Co., 33 P.3d at 805.

Because Thornton has an appropria-tive right to water, section 37-92-305(8) requires the water court or water referee to accept proposed terms or conditions designed to prevent injury to Thornton. § [ XXX-XX-XXXX ](8). If the substitute supply of water provided by Denver's Augmentation Plan renders the water supply Thornton receives unsuitable for Thornton's normal use of the water in comparison to the water it would otherwise receive at its point of diversion if Denver's Augmentation Plan had not been instituted, Thornton's property right in the use of its water is impaired by the substitute supply. See Brighton Ditch Co. v. City of Englewood, 124 Colo. 366, 237 P.2d 116 (1951). Thus, prior to its approval of the augmentation plan, the water court properly determined that senior appropriators would not be injured based upon a prediction made at the decree's entry. § 37-92-805(5). Under the retained jurisdiction provision of the augmentation plan decree in this case, the authority to make the determination of injury to Thornton at the time of the operational stage of the augmentation plan remains with the water court notwithstanding the WQCA and the WQCC's general authority over water quality issues. See § 25-8-104(1); 37-92-305(5).

Retained jurisdiction protects Thornton by allowing the water court to reconsider its initial determination that Thornton and other senior appropriators would not be injured by Denver's Augmentation Plan. See § 37-92-304(6). This second stage of the water court's determination of non-injury is important because the water court cannot always predict the actual effects of an augmentation plan. See Farmers Res. & Irr. Co., 33 P.3d at 805. In the interest of finality, the water court sets the period of retained jurisdiction at the period of time it finds necessary to preclude or remedy any injury that may emerge once the augmentation plan becomes operational. Id. at 806. The retained jurisdiction provision therefore provides the water court with flexibility to implement programs that maximize the beneficial use of water without sacrificing the vested water rights of Thornton and other senior appropriators. City of Florence, 4798 P.2d at 157.

Retained jurisdiction should be invoked where the actual operation of an augmentation plan reveals that substituted water is unsuitable for a senior appropriator's normal use of the water in comparison to the quality of the water it would otherwise receive at its point of diversion if the augmentation plan had not been instituted. See § 37-92-305(5). - The water court read Thornton's petition as claiming injury from increased knowledge of the detrimental water quality effects of Bi-Clity effluent and overlooked the city's allegation that the actual operation of Denver's Augmentation Plan made the water Thornton receives at its diversion point unsuitable for Thornton's use of the water as a municipal water supply. Thornton's increased knowledge of potential health consequences of using Bi-City effluent as a replacement supply is important only to the extent that it aids in establishing the unsuitability of the water. The pivotal issue is the water's suitability. Thornton can use its increased knowledge to prove injury from Denver's Augmentation Plan only by demonstrating that the quality of the Bi-city effluent makes the water supply unsuitable for the city's normal use as a municipal water supply. Thornton's increased knowledge of the health consequences of using the effluent might demonstrate a decrease in water quality without proving the unsuitability of the effluent as a substitute water supply. Under such cireumstances, Thornton would not be "injured" by Denver's Augmentation Plan. However, it is possible for Thornton to use its increased knowledge of the potential health consequences of using Bi-City effluent to convince the water court that the water supply it receives after the augmentation plan was put into place is unsuitable for Thornton's normal municipal use. It is the unsuitability of the water, rather than Thornton's understanding of possible health consequences of its use, that triggers the retained jurisdiction provision.

Water courts have a responsibility to protect the water rights of Thornton and other senior appropriators. § 37-92-305(8). This responsibility is very important because senior appropriators like Thornton must accept substituted water in replacement for water they would otherwise receive, so long as the replacement water is "of a quality and quantity so as to meet the requirements for which the water of the senior appropriator has normally been used." §

When confronted with Thornton's claim of injury from the quality of the Bi-City effluent, the water court had an obligation to hold a hearing, with Thornton bearing the burden of going forward, to address the injury to Thornton as a result of the actual operation of Denver's Augmentation Plan in comparison to the quality of supply it would receive absent the institution of the augmentation plan or, in the alternative, to extend the period of retained jurisdiction until the pending Denver exchange case could address the common water quality issues. Instead, the court found that the seven-year period of retained jurisdiction could not be invoked to address the quality effects of the use of Bi-City effluent as a substitute water supply in Denver's Augmentation Plan.

We determine that this case presents a situation in which the actual operation of Denver's Augmentation Plan creates a cognizable issue of injury to Thornton not anticipated by the water court at the time of its initial decree. The general responsibility of the WQCC over water quality issues does not change the retained jurisdiction analysis because the water court retains authority over injury determinations relating to water quality made pursuant to section 37-92-304(6) despite the WQCA. Similarly, Thornton's initial stipulation to the suitability of the Bi-City effluent did not preclude the water court from reconsidering potential injury to Thornton during the retained jurisdiction stage of its injury analysis. Accordingly, we hold that the water court improperly refused to hold a hearing on Thornton's alleged injury from the operation of Denver's Augmentation Plan or to extend the period of retained jurisdiction until the suitability of Bi-City effluent as a replacement supply could be determined in the pending Denver exchange case. The judgment of the water court is reversed and the case remanded to the water court for further proceedings consistent with this opinion.

      . - Although Thornton initially argued water quantity injuries, the parties agree that quantity is not an issue with respect to retained jurisdiction in this case and we do not address the issue here.

      . The Centennial Water and Sanitation District, the City of Englewood, Henrilyn Irrigation District, and the City of Aurora also entered into stipulated decrees prior to trial, none of which is at issue here.

      . The water court found Thornton had alleged an arguable injury so that its reliance on the retained jurisdiction provision of section 37-92-304(6) was not wholly frivolous or lacking in subject-matter jurisdiction. Id. The water court thus declined to award attorney's fees to Denver. Td.

      . The doctrine of prior appropriation imposes three requirements for acquiring a water right: intent to make an appropriation, a taking of the water, and an application of the water to beneficial use. Colo. River Water Conservation Dist. v. Rocky Mountain Power Co., 158 Colo. 331, 333, 406 P.2d 798, 799 (1965).

      . Section 6 of article XVI of the Colorado Constitution recognizes the prior appropriation doc-trime and the corresponding right to divert unappropriated waters of any natural stream to beneficial use. Colo. Const. art. XVI § 6. Section 5 of the constitution makes the unappropriated water of every natural stream within Colorado the property of the people of the state. Colo. Const. art. XVI § 5. Chapters 80 through 93 of article 37 of the Colorado Revised Statutes concern various aspects of water rights. Relevant to the discussion here are the provisions of the WRDAA, §§ 37-92-101, et seq.


source: Caselaw Access Project

author: Justice COATS

license: Public Domain

text:
    The PEOPLE of the State of Colorado, Petitioner, v. Russell S. RATH, Respondent.
    No. 99SC916.
    Supreme Court of Colorado, En Banc.
    April 8, 2002.
    Rehearing Denied April 29, 2002.

      Ken Salazar, Attorney General, Paul Koch-ler, Assistant Attorney General, Denver, CO, Attorney for Petitioner.
    David S. Kaplan, Colorado State Public Defender, Julie Iskenderian, Deputy State Public Defender, Denver, CO, Attorney for Respondent.
   Justice COATS

delivered the Opinion of the Court.

The People sought review of the court of appeals' judgment reversing the defendant's convictions for first degree sexual assault and second degree kidnapping. The court of appeals found that the trial court abused its discretion in admitting evidence of two prior instances of uncharged misconduct by the defendant, involving two other young women, primarily because the defendant conceded he was the person who gave the victim a ride on the day in question and because it considered the other acts insufficiently similar to the current charge. We hold that the trial court did not abuse its discretion in admitting the evidence of these other acts pursuant to CRE 404(b), and therefore we reverse the judgment of the court of appeals and remand with instructions to reinstate the defendant's convictions.

I. FACTUAL AND PROCEDURAL BACKGROUND

The charges against the defendant arose from the alleged rape of fifteen-year-old T.C. The prosecution's theory was that just before noon on October 18, 1995, while walking home from school on a rural mountain road in Jefferson County near Nederland, the vie-tim was offered a ride by the defendant, taken to a secluded dirt road, dragged down a hillside, and raped by him. The prosecution presented its case at trial largely through the testimony of the victim; relatives, police, and hospital personnel to whom she reported the assault; and coworkers of the defendant to whom he had given contradictory accounts of the incident. The prosecution also presented the testimony of four other women, each of whom was approached on a public street by the defendant, offered a ride, taken to a secluded place, and allegedly subjected to some form of attempted or completed sexual assault. Although the defendant did not testify at trial, his contention that he had merely given the victim a ride and that she was a "pathological liar," who fabricated the sexual encounter to get attention from family members, was presented through cross-examination, defense witnesses to the lack of corroborating physical evidence, and his counsel's opening and closing statements.

As the only admitted witness of the attack, the victim provided the only first-hand testimony about the details of the currently charged assault. She testified at trial that she accepted the defendant's offer of a ride to a point near her home. Upon arriving there the defendant refused to stop, saying that he needed to go to the store and would then take her back to where she wanted to go. Instead of going to a store, however, the victim testified that the defendant took her to a secluded dirt road where he stopped the vehicle and told her that he wanted to show her something in the woods. While she at first refused to get out of the truck, she eventually relented, whereupon the defendant physically dragged her down the adjacent hillside and forcefully sexually assaulted her by vaginal intercourse.

Among other details, she testified that the defendant removed all of their clothing except his shirt and commented during the assault that she had a "nice mole" on her leg. She also testified that following the assault, she accepted a ride from the defendant to a point near her destination where he apologized for his conduct, saying that next time he would not do this sort of thing, and allowed her to leave. After walking home, she vomited and immediately undressed to shower, finding a twenty dollar bill in her pant leg that she did not have before the assault. After showering, she called family members and eventually the police.

The subsequent emergency room examination produced no physical evidence of sexual assault. Similarly, the defense produced evidence indicating that the tire tracks found on the road near the scene identified by the victim did not match the tires on the defendant's truck at the time the police made contact with him several weeks later and evidence challenging the feasibility of the victim's time estimates. There was, however, bruising on the victim's shins where she claimed the defendant sat while pulling off her clothing and an indentation on her abdomen that could have been caused by weight pressing against her cigarette package.

The prosecution also presented the testimony of the four women who claimed to have been picked up and taken to a secluded location during a ten-month period in 1981-82, when they were between twelve and twenty years old, by someone later identified as the defendant. Although the details of the incidents varied, each began with the offer of a ride from the defendant, which the young women accepted either voluntarily or as the result of threats, followed by a drive to a secluded location and some indication by the defendant that his intent was to have sexual relations. In two of the cases, the women were actually sexually assaulted by penetration; in a third case the woman, LL., testified that the defendant physically forced her into the back of his camper, climbed on top of her, and fondled her breasts, until her resistance and erying led the defendant to let her go to find her own way home; and in the last case, the twelve-year-old girl, to whom the defendant had given five dollars to allow herself to be photographed, fled when he crawled into his truck bed and enticingly invited her to join him to see his camera.

In three of the cases, the defendant showed the women a camera and either took photos or described his interest in taking photos of young women and either gave the young women a small amount of money as an enticement or left a small amount of money with them after the assault. In the two cases in which the defendant was able to complete the sexual penetration (one by vaginal intercourse and the other by forced fellatio), the defendant removed all of his clothing but his shirt and managed to partially or completely disrobe his victim, commenting about some physical feature that became visible-in one case a sear and the other the woman's "fuzzy," unshaved legs. After each completed assault, the defendant was conciliatory or matter-of-fact about doing this sort of thing and offered to drive the victim where she wanted to go.

The jury found the defendant guilty of both second degree kidnapping and first degree sexual assault, for which he was sentenced to concurrent terms of sixteen and eight years, respectively. On direct appeal, the court of appeals reversed, holding that although evidence of two of the prior sexual transactions involving the defendant were properly admitted, the trial court abused its discretion in admitting the other two. It held that the admission of the incidents involving the women identified as LL. and P.B., in which the encounters ended short of sexual penetration, was error because they were not related to the occurrence of sexual intercourse, which it considered the only "contested" issue at trial, and because they were not "sufficiently substantially similar [to the current charges] to be introduced under CRE 404(b) and § 16-10-301, C.R.8.1998." People v. Rath, No. 96CA1773, slip op. at 1 (Colo.App. June 3, 1999).

II. ADMISSIBILITY OF UNCHARGED MISCONDUCT EVIDENCE

The admissibility of evidence of uncharged criminal misconduct is expressly limited by the Colorado Rules of Evidence. According to CRE 404(b), evidence of other crimes, wrongs, or acts is not admissible to prove the character of a person in order to show that he acted in conformity with that character on a particular occasion. The rule is in accord with the long-standing policy of the English and American law of evidence that when evidence is admitted for this purpose, which is sometimes characterized as the propensity of the accused to commit crime, even though it may be logically relevant in some measure, the prejudicial effect of the evidence always outweighs its probative value, and it is, for . that reason, always inadmissible. 1A Wigmore, Evidence § 58.2, at 1212 (Tillers rev. 1983). When offered for any other purpose, however, the evidence is not necessarily barred. The rule enumerates several examples of reasons for which evidence of other crimes may be admissible. "As the rule indicates, there are numerous other uses to which evidence of eriminal acts may be put, and those enumerated are neither mutually exclusive nor collectively exhaustive." 1 Charles T. McCormick, McCormick on Evidence § 190, at 659 (John W. Strong, 5th ed. 1999).

In order to be admissible, evidence must be relevant; and unless otherwise provided by constitution, statute, or rule, all relevant evidence is admissible. CRE 402. Evidence is relevant, in the logical sense, as long as it is "evidence having any tendency to make the existence of any fact that is of consequence to the determination of the action more probable or less probable than it would be without the evidence." CRE 401; see People v. Carlson, 712 P.2d 1018, 1021-22 (Colo.1986). Even logically relevant evidence may be excluded, however, "if its probative value is substantially outweighed by the danger of unfair prejudice." CRE 408; see Spoto v. People, 795 P.2d 1314, 1318 (Colo.1990).

Evidence of other, uncharged crimes may therefore be admissible if, but only if, it is logically relevant for some reason apart from an inference that the defendant acted in conformity with a character trait, and if the probative value of the evidence for that other reason is not substantially outweighed by the other policy considerations of Rule 408. This court has previously considered the relevancy of other-crimes evidence within the scheme of the rules and has analyzed the requirements of CRE 401-404 in four parts. Spoto, 795 P.2d at 1818. First, the other-crimes evidence must be offered as relating to a material fact. Id. Second, it must be logically relevant by tending to make that material fact more probable or less probable. Third, its logical relevance must be independent of the intermediate inference prohibited by CRE 404(b), that is, the evidence must be probative for some logical reason other than "that the defendant committed the crime charged because of the likelihood that he acted in conformity with his bad character." Id. And fourth, the probative value of the evidence for that other reason may not be substantially outweighed by the danger of unfair prejudice caused by admitting the other-crimes evidence. Id.

In considering the effect of CRE 404(b) on the admissibility of other-crimes evidence, we have also emphasized that "[the basic reasons for excluding other-crime evidence were set forth in Stull [v. People], 140 Colo. 278, 344 P.2d 455, and these reasons are no less applicable today than they were prior to the adoption of the Rules of Evidence." People v. Garner, 806 P.2d 866, 372 (Colo.1991). Rule 404(b) is in accord with the long-accepted proposition that an inference of specific conduct drawn from evidence of criminal character is never sufficiently probative to be admitted to prove the accused committed a particular crime. See Spoto, 795 P.2d at 1318. The inherent and universally recognized danger that evidence of uncharged misconduct will influence a fury to convict for an improper and unfairly prejudicial reason always serves as a strong counterweight to any probative value it may have.

We have recognized, however, that with the adoption of the rules of evidence, the analysis of the admissibility of such evidence has been significantly altered, making it admissible in some cases in which it previously might have been excluded. Garner, 806 P.2d at 370. For example, the prosecution's burden of showing that the defendant actually committed the uncharged erime or act, which is required for its admission, has been reduced. Id. (holding that the former clear- and-convincing-evidence standard of People v. Botham, 629 P.2d 589 (Colo.1981), has been supplanted by the preponderance-of-the-evidence standard dictated by CRE 104(a)). Similarly, the inclusionary formula of the rules of relevancy, permitting the admission of evidence unless its probative value is substantially outweighed by the danger of unfair prejudice, creates a rule more favorable for admission. See id. at 370, 378 n. 5 (noting that the balancing test of CRE 403 has effectively overruled the pre-rules formulation of People v. Honey, 198 Colo. 64, 67, 596 P.2d 751, 754 (1979), which inverted the policy choice and required the exclusion of other-crimes evidence unless its probative value outweighed its prejudicial effect); see generally (Edward J. Imwinkelried, Uncharged Misconduct Evidence § 2:31 (2001) (discussing change under Fed.R.Evid. 404(b) to inclusionary view).

Perhaps most significantly, to the extent that the law in this jurisdiction had come to exclude evidence of other crimes unless it was offered for and met the strictures of certain narrowly cireumseribed categories, see, e.g., Honey, 198 Colo. at 67-68, 596 P.2d at 753-54, the rule is more open to general considerations of relevance. CRE 404(b) only requires the exclusion of evidence of other crimes, wrongs, or acts offered for the purpose of proving the character of a person in order to show that he acted in conformity therewith. Although the prosecution must articulate a precise evidential hypothesis by which a material fact can be permissibly inferred from the prior act that is independent of the inference forbidden by CRE 404(b), upon a showing of logical (CRE 401) and legal (CRE 403) relevance under that hypothesis, evidence of other crimes will not be excluded under the rules of relevance. See Spoto, 795 P.2d at 1818-19.

III. ADMISSIBILITY OF TRANSACTIONS INVOLVING LL. AND P.B.

In order to prove that the defendant in this case was guilty of kidnapping and sexual assault, the prosecution was required to show that he knowingly seized and carried the victim from one place to another without her consent and that he knowingly inflicted sexual intrusion or penetration on her by physical force or violence. The trial court heard the prosecution's pretrial motion to admit the evidence of uncharged misconduct, and in a written order granted admission of all four transactions for the purpose of showing a common plan, scheme or design, modus operandi, motive or intent, and to refute the defendant's contention that the alleged vice-tim's claim of sexual intercourse or contact was a fabrication.

(1) MATERIAL FACT

The other-crimes evidence was therefore clearly offered as relating to a number of facts that were material or of consequence to the determination of the action, as required in the first step of the Spoto analysis Some of the purposes for which the evidence was admitted were actual elements of the charged crimes, or ultimate facts to be proved, while others were intermediate or evidential facts, themselves probative of ultimate facts. Generally, in a criminal prosecution the ultimate facts or elements consist of showing that the accused committed the guilty act, sometimes described as the "identity" of the accused, and that he did so with the required intent or state of mind and without legal excuse or justification. Plan, scheme, design, modus operandi, and motive, while not usually elements or ultimate facts themselves, are among, or closely related to, those examples of permissible reasons enumerated in the rule and are well-accepted methods of proving the ultimate facts necessary to establish the commission of a crime, without reliance upon an impermissible inference from bad character.

Although the trial court expressly omitted "identity" from the list of purposes for which the evidence would be admitted, it did so not from any failure to understand that the identity of the accused was necessarily a material element of the crime but rather because it considered the question of "identity" to be no longer at issue in either the charged offense or the uncharged misconduct. The defendant's theory or concession, however, extended only to an admission that he had given the victim a ride about the time and place of the alleged assault. The trial court therefore only found unnecessary, and only refused to admit, the other-crimes evidence to prove that the defendant was the person to whom the victim referred as giving her a ride and assaulting her. It in no way suggested, however, that the other-crimes evidence was unnecessary or inadmissible to prove that the defendant actually committed the guilty act. See State v. Griffin, 142 Ohio App.3d 65, 758 N.E.2d 967, 974 (2001)("Iden-tity is not synonymous with mere presence."). Quite the contrary, by admitting the evidence as supportive of the victim's claim of sexual intercourse, as well as for common plan, scheme or design, modus operandi, and motive, the trial court made clear its intent to admit the evidence of other crimes precisely for the purpose of proving that the prohibited act was committed.

(2) LOGICAL RELEVANCE

Evidence of the incidents involving LL. and P.B., upon which the court of appeals reversed, was also logically relevant to prove a material fact, as required in the second step of Spoto. Those incidents were part of a pattern of behavior by the defendant demonstrating a method for committing crimes like those for which he was on trial. Even though these two incidents were terminated by action of the victims before any completed act of sexual penetration, they were evidence from which the jury could find that the defendant had a history of offering young women a ride as a ruse to isolate them and have sex with them, regardless of their consent.

Evidence indicating that the defendant had offered young women a ride in the past for the purpose of having sex had at least some tendency to make it more probable as a logical matter that he intended to have sex with the victim in the charged offense, after admittedly offering her a ride under similar cireumstances. In conjunction with evidence that the defendant had sexually assaulted women on certain past occasions after similarly picking them up, as well as the victim's testimony in this case that the defendant sexually assaulted her after picking her up, evidence of examples of the defendant's scheme to pick up young women for the purpose of sexual gratification also had at least some tendency to make it more probable that he had sexual relations with the victim in this case. See Wigmore, supra, §§ 302-03. Rule 401's requirement of logical relevance is satisfied as long as the evidence in question has any tendency to make a fact of consequence more probable than it would be without that evidence.

(3) INDEPENDENCE OF INFERENCE FROM BAD CHARACTER

The chain of logical inferences from the evidence of the defendant's prior conduct in step two is also independent of any inference that he must have committed a sexual assault in this case because he is a person of criminal character. The inference relied on arises not from the criminal character of the accused but from the demonstration of his pattern of using a particular technique to accomplish a particular end. The evidence tended to show that when the defendant did certain things, in a certain way, a number of times in the past, he did so with a eriminal purpose, and he took affirmative action to accomplish that purpose. The evidential hypothesis by which the commission of the guilty act could properly be inferred is included in the term mo-dus operandi, which is a traditional, if not precisely defined, expression of a legitimate way of proving the ultimate facts in a criminal case without reliance on an inference from bad character.

Although the other uncharged acts were therefore logically relevant without reliance upon the one impermissible inference, the more difficult question, as is virtually always the case, was whether the evidence of the defendant's other crimes was sufficiently probative for legitimate purposes when balanced against the danger of unfair prejudice.

(4) CRE 403

In the final step of the analysis, the trial court necessarily retains a great deal of discretion, bearing in mind that the admission of uncharged misconduct always has a substantial potential for unfair prejudice. People v. Nuanez, 973 P.2d 1260, 1263 (Colo.1999); People v. Ibarra, 849 P.2d 33, 38 (Colo.1998). Beyond finding logical relevance, it must assess the weight that would be added to the prosecution's case by admitting the other-crimes evidence. Unlike Rule 401's "relevance," Rule 4083's "probative value" is not considered in isolation but signifies the "marginal" or "incremental" probative value of evidence relative to the other evidence in the case. See Old Chief v. United States, 519 U.S. 172, 184-85, 117 S.Ct. 644, 186 L.Ed.2d 574 (1997)(citing 1 Charles T. McCormick, McCormick on Evidence 782 & n. 41 (John W. Strong ed. 4th ed. 1992)); People v. Saiz, 82 P.3d 441, 446 (Colo.2001)(citing Nuanmez, 978 P.2d at 1263). Therefore, the court must weigh "the logical force of the evidence and the proponent's need for the evidence," in light of other available evidence. Martin v. People, 738 P.2d 789, 794 (Colo.1987). Finally, it must assess the danger of unfair prejudice and exclude the evidence if its "incremental" probative value would be substantially outweighed by that danger. Id. (where defendant stipulated to lawful confinement, mitti-mus showing his conviction for murder was not additionally probative of that element and should have been excluded as unfairly prejudicial).

The probative value or logical force of evidence of other crimes cannot be determined according to any precise formula. Depending on the purpose and theory of logical relevance advanced for its admission, the assessment of its probative value may involve a host of factors, including the distinctiveness of the other erimes and their relationship to the charged offense in terms of time and similarity. Contrary to the apparent assumption of the court of appeals, however, CRE 404(b) contains no separate requirement of similarity. See Spoto, 795 P.2d at 1320 ("generally no similarity of conduct requirement concerning evidence of other crimes, wrongs or acts"). Under a particular evidential hypothesis, similarity may not be significant at all, and if significant, the nature and extent to which similarity is important may vary greatly.

When evidence of other crimes is offered to show a defendant's motive for committing a charged offense or to show that other crimes were part of the preparation or plan to commit a charged offense, similarity of the crimes often has no significance whatsoever. See, eg., United States v. Brooks, 125 F.3d 484 (7th Cir.1997)(evidence of defendant's prior drug use admissible as motive for bank robbery); United States v. Lamb, 575 F.2d 1310 (10th Cir.1978)(allowing under Fed.R.Evid. 404(b) evidence of prisoners' escape, kidnapping of guard, and commandeering of an apartment to show the prisoners' "plan" to commit the charged robbery); United States v. Haldeman, 559 F.2d 31 (D.C.Cir.1976)(evidence of prior uncharged office break-in admissible in trial for charged cover-up). Even when evidence of other crimes is offered to demonstrate a common method or modus operandi, the degree of similarity necessary to give the evidence sufficient probative force for admission varies considerably depending upon the element or ultimate fact for which it is offered. Evidence of design or method offered to prove that the defendant, as distinguished from anyone else, committed the charged offense generally depends much more heavily on the distinctiveness and similarity of the crimes than evidence offered merely to prove that the defendant acted intentionally. See United States v. Fields, 871 F.2d 188 (1st Cir. 1989)("[A] 'much greater degree of similarity . is required when the evidence of the other crime is introduced to prove identity' than when it is introduced for another of the myriad of reasons allowed under [Fed. R.Evid.] 404(b)...."); Wigmore, supra, §§ 302-04 (distinguishing the degree of similarity required to prove identity from the lesser degree required to prove intent or mistake).

Other-crimes evidence demonstrating a common design or modus operandi has been admitted in prosecutions for sexual assault not only to prove who committed the crime but also to prove that the alleged sex act actually occurred. See, eg., People v. Luczak, 306 Ill.App.3d 319, 239 Ill.Dec. 698, 714 N.E.2d 995, 1001 (1999); People v. Fuller, 117 Ill.App.3d 1026, 73 Ill.Dec. 474, 454 N.E.2d 334, 341-48 (1983). Like admission of other-crimes evidence to prove intent, its admission to prove the commission of the guilty act when identity is already conceded does not depend upon distinguishing the defendant from others who also had the capacity and opportunity to commit the crime. Similarly, where the guilty act consists of an act like sexual intercourse, the other crimes need not make it more likely that the victim's injury was the result of an act of the defendant than of natural accident. See United States v. Woods, 484 F.2d 127 (4th Cir.1973)(admitting evidence that over a twenty-five-year period, nine children in defendant's custody experienced twenty cyanotic episodes, for purpose of proving commission of actus reus). Evidence of other acts to prove the commission of the guilty act is admissible under the various logical theories or evidential hypotheses that apply to other ultimate facts, but as with intent generally, the distinctiveness of preparatory acts is less significant in proving the actor's purpose or intention than in showing the identity of the actor.

Evidence of the defendant's uncharged misconduct is clearly not admissible solely to bolster the testimony of a prosecution witness, but neither is it excluded merely because it may have that effect. See Luczak, 714 N.E.2d at 1001. If other-crimes evidence is otherwise admissible to prove a material fact by showing, for example, a common design or modus operandi, it may simultaneously corroborate the victim's testimony of the existence of that fact. Moreover, where disputed testimony of the victim is the only direct evidence of the commission of the guilty act, additional evidence that is probative of that fact may have particular "marginal" or "incremental" probative value.

Although there were obvious differences in the cireumstances surrounding each transaction admitted in this prosecution, they shared a number of significant characteristics that evidenced a pattern of behavior rather than isolated prior incidents. See Garner, 806 P.2d at 375 ("[I}t is not essential that the means of committing the other crimes replicate in all respects the manner in which the crime charged was committed.") The two prior incidents that actually resulted in sexual penetration, in addition to involving similar preparatory acts, included distinctive and unpredictable personal details of the commission and aftermath of the assault that were so similar to those alleged by the victim of the charged crime as to virtually compel an inference that the act occurred or that the victim was acting in collusion with the prior victims. - Particularly, the combination of the defendant's disrobing preference, his fixation during the assault on meaningless physical anomalies of the victim, and his insistence on paying the victim as if she had consensually performed a service would be difficult to invent in the absence of a similar sexual encounter.

In addition, however, the combination of all four incidents added substantial weight to the inference of a technique to isolate young women for the purpose of having sex. A greater number of incidents of similar behavior is important in proving that it is directed or purposive rather than coincidental. See Spoto, 795 P.2d at 1320; Wigmore, supra, § 302. Because the defendant did not admit the assaults in any of the cases, each of the five was to some extent dependent upon the others to prove that sexual encounters were intended by the defendant's preparatory behavior and that sexual assaults actually occurred unless the victims were able to escape. Although the incidents involving L.L. and P.B. were interrupted by the victims' escape, they were nevertheless similar in significant aspects and substantially contributed to the inference that the defendant's technique of isolating vulnerable females by offering them a ride and driving them to a secluded location was preliminary to and for the purpose of sexual gratification.

While preparatory acts or even overt attempts, standing alone, may sometimes be insufficiently probative of a defendant's unfulfilled intention, in conjunction with evidence of consummated erimes resulting from similar preparations, they can form a pattern of behavior that is probative of the commission of the act. Furthermore, to the extent that, the incidents are further removed from a completed crime, they correspondingly present less of a danger of unfair prejudice. To the extent that the incidents involving L.L. and, especially, P.B were less probative of the defendant's intention to commit sexual assault, they were also less serious, heinous, or egregious, than the three sexual assaults presented to the jury and were less likely to have an inflammatory effect.

Trial courts are necessarily accorded considerable discretion in deciding questions concerning the admissibility of evidence, and an abuse of that discretion will be found only upon a showing that the ruling was manifestly arbitrary, unreasonable, or unfair. People v. Harris, No. 00SC185, slip op. at 11, 2002 WL 8372916 (Colo. Mar.11, 2002). Because the balance required by CRE 403 favors admission, a reviewing court must afford the evidence the maximum probative value attributable by a reasonable fact finder and the minimum unfair prejudice to be reasonably expected. See People v. Gibbens, 905 P.2d 604, 607 (Colo.1995). Evidence of uncharged crimes has a distinct and unmistakable potential for unfair prejudice, but unfair prejudice within the meaning of the rule still refers only to "an undue tendency on the part of admissible evidence to suggest a decision made on an improper basis" and does not mean prejudice that results from the legitimate probative force of the evidence. Id. at 608.

The trial court heard the motion to admit evidence of other crimes and the objections to it. It demonstrated its awareness of the applicable law controlling the admission of other-crimes evidence, and it made findings as to each of the four steps of the Spoto test. It even modified the list of purposes for which the evidence would be admissible that was proposed by the prosecution, notably disallowing the other-crimes evidence to identify the defendant. In light of the considerations already articulated, it cannot be fairly said by a reviewing court that the trial court abused its discretion in finding that the probative value of the other-crimes evidence admitted in this case was substantially outweighed by the danger of unfair prejudice.

IV. CONCLUSION

In finding reversible error, the court of appeals mispereeived the import of our application of the Colorado Rules of Evidence to the introduction of uncharged criminal misconduct evidence and misapplied the four-part analysis of People v. Spoto. Properly considered, the concerns of the court of appeals amount to a disagreement about the balance of probative value and prejudicial effect required by CRE 403. Accordingly, the judgment of the court of appeals is reversed and the case is remanded with directions that the judgment of conviction and sentence be affirmed.

      . We granted the People's petition for certiorari on the following question:
      Whether the court of appeals erred in holding, based on its application of section 16-10-301, 6 C.R.S. (1999), and CRE 404(b), that the trial court abused its discretion and committed reversible error in admitting prior act evidence relating to victims LL. and P.B.
      We denied the Defendant's cross-petition for certiorari on the following two issues:
      1. Whether the trial court committed reversible error when it permitted the prosecutor to introduce "similar" transaction evidence regarding J.H. and T.C. while was stale, dissimilar, irrelevant, and unduly prejudicial.
      2. Whether Defendant was erroneously deprived of access to the department of social services records related to the alleged victim.

      . Prior to the adoption of the rules of evidence, the Colorado General Assembly had made clear by statute that evidence of other criminal transactions would be admissible in prosecutions for sexual offenses for the same reasons it was admissible in prosecutions for other offenses. See § 16-10-301, 8A C.R.S. (Supp.1995)(substantially amended effective July 1, 1996, see ch. 280, sec. 21, 1996 Colo. Sess. Laws 1578, 1589). Whether or not the statute would have permitted other-crimes evidence in prosecutions for sexual offenses even more liberally than CRE 404(b), see Pigford v. People, 197 Colo. 358, 593 P.2d 354 (1979); People v. Opson, 632 P.2d 602 (Colo.App.1980), apart from separately requiring a prima facie case of the charged offense (which is not at issue on this appeal), nothing in the statute purported to exclude evidence that would otherwise be admissible under the rule, nor has such a suggestion been made by the parties to this appeal. It is enough therefore that the district court did not abuse its discretion in admitting the other crimes evidence at issue here pursuant to the Colorado Rules of Evidence.

      . Although the concept of materiality no longer has independent significance in the scheme of the rules, and is instead subsumed within the notion of logical relevance, see CRE 401, we have found it helpful in emphasizing the obligation of the prosecution to offer (and the court to admit) other-crimes evidence only for specific purposes, to distinguish the two concepts.

      . - In its holding the court of appeals added to the first step of the Spoto analysis the requirement that the material fact for which the other-crimes evidence is offered be "contested." Slip op. at 3. Whether a material fact is contested clearly affects the need for or incremental probative value of the evidence offered to prove it, but it does not make the fact itself any less material or the evidence offered to prove it any less logically probative. The court of appeals therefore incorrectly found that the evidence failed to satisfy the first step the Spoto test.

      . Because the question of whether the accused committed the criminal act contains the subques-tions of whether the act was committed by someone and whether, if so, the accused was the person who committed it, the broader question has sometimes been separated into the questions of "identity' and "commission of the actus reus." See, eg., Imwinkelried, supra, ch.4.

      . At the motions hearing the parties indicated that they had a "stipulation to ID," and defense counsel made clear at both the hearing and in his opening statement at trial that the defendant was the person who picked the victim up and gave her a ride. The precise limits and legal effect of any concession by the defendant remain unclear, however, because no stipulation was ever submitted to the jury.

      . See generally Imwinkelried, supra, §§ 8:07 ("[UJnder some theories of logical relevance, the uncharged act need not be similar to the charged act. Moreover, even among theories requiring similarity, the required degree of similarity varies. The modus theory of identifying the defendant as the criminal requires the highest degree of similarity while [Dean Wigmore's] doctrine of chances demands less similarity to prove the occurrence of an actus reus or guilty state of mind"), 5:08 (degree of required similarity less when proving intent through Wigmore's doctrine of chances than when proving identity through modus operandi).