By John Sittler
The Colorado Supreme Court recently reaffirmed the standards for which an Applicant must prove “no-injury” to vested water rights when applying for approval of a plan for augmentation. This decision, while consistent with prior law, underscores the evidentiary burden that applicants must meet to obtain conditional groundwater rights in over-appropriated basins. The Court also clarified the scope of its retained jurisdiction regarding plans for augmentation. [Concerning the Application for Water Rights of the Town of Firestone, 2025 CO 33(Colo. May 27, 2025).]
Overview of Plans for Augmentation Including Conditional Groundwater Rights
A brief overview of pertinent Colorado water law is helpful to understand the facts and claims at issue in this case. Colorado operates under a relatively pure version of the prior appropriation system, under which water rights are administered according to priority dates. In order to prevent curtailment of junior water rights during times of a downstream call, a water right owner may apply to the water court for approval of a plan for augmentation. A plan for augmentation is a court-approved water supply plan that replaces water back into the stream system to offset depletions from a new junior water use.
Colorado water law also recognizes both conditional and absolute water rights. An absolute water right is one that is fully developed, meaning the owner has put the water to beneficial use. In contrast, a conditional water right is one that has not yet been developed. A decreed conditional water right preserves the owner’s priority within the prior appropriation system while allowing for future development of the intended water project. Vermillion Ranch Ltd. P’ship v. Raftopoulos Bros., 307 P.3d 1056, 1064 (Colo. 2013). Conditional water rights often require a plan for augmentation to protect senior water rights against injury. The “no-injury” doctrine requires applicants to demonstrated that their proposed diversions will not cause injury (i.e., a diminution of available water) to vested senior water rights. Farmers Reservoir & Irrigation Co. v. Consol. Mut. Water Co., 33 P.3d 799, 807 (Colo. 2001).
Surface water rights may not require a plan for augmentation because they can be immediately curtailed during a call to prevent injury to downstream senior water rights. However, depletions from groundwater rights are “lagged” meaning that the depletions may take months, or longer, to affect the nearest surface stream system. Thus, conditional groundwater rights in over-appropriated basins, which include Division 1 at issue in this case, must be accompanied by an approved plan for augmentation. City of Aurora ex rel. Util. Enter. v. Colo. State Eng’r, 105 P.3d 595 (Colo. 2005) (holding that “a conditional right to pump water that would injure senior appropriators may only be decreed in conjunction with an augmentation plan.”). Analysis of lagged groundwater depletions requires precise engineering calculations to determine the amount and timing of those out-of-priority depletions and how those depletions will affect downstream senior water rights. A standard engineering methodology for calculating lagged depletions relies on a computational model that uses Unit Response Functions (URFs) to quantify the timing and amount of depletions that a nearby surface stream will experience as a result of new well pumping. “If an applicant for a new conditional groundwater right fails to meet their burden of showing non-injury, including by submitting inaccurate or insufficient lagged depletion calculations in their augmentation plan, then a water court is obligated to dismiss the application.” Firestone at ¶ 13 (citing Buffalo Park Dev. Co. v. Mountain Mut. Reservoir Co., 195 P.3d 674, 684 (Colo. 2008)).
Background and Procedural History
The Town of Firestone filed an Application with the Division 1 Water Court in 2019 seeking, among other things, several new conditional surface and groundwater rights, as well as approval of a plan for augmentation. The Town applied for these water rights as part of its planning measures that predict population doubling by 2050 and the need for additional municipal water supplies. Numerous parties opposed the application, although Firestone was able to reach stipulations with all but the St. Vrain Sanitation District. St. Vrain specifically raised concerns about Firestone’s claims for three conditional well fields.
At trial before the water court, Firestone provided quarter-quarter section legal descriptions for each of the three well fields, but did not specify exact well locations or the number of proposed wells within each well field. Thus, the URFs were based on estimated locations and number of wells, and Firestone proposed to later refine the URFs and lagged depletion models after construction of the wells.
After Firestone concluded its case-in-chief, St. Vrain filed a motion to dismiss arguing that the proposed well fields lacked the specificity necessary for an accurate URF analysis, and that Firestone’s proposal to refine the URF modeling at a later date improperly shifted the burden of proving no-injury to a later proceeding. The water court agreed and partially granted the motion, dismissing the portions of the application related to the three well fields and the corresponding portions of the plan for augmentation. The water court’s ruling found that Firestone’s URF calculations, based on “estimated, potential” well locations were insufficient to prove a showing of no-injury. The court specifically relied on Firestone’s own expert who testified that inaccurate URF calculations could lead to underestimated lagged depletions, which could ultimately injury senior water rights. Regarding Firestone’s proposal to refine the URF modeling after well construction, the water court held that, because it was unable to find for Firestone on the issue of non-injury, it would be inappropriate to retain jurisdiction over the application. Firestone then appealed directly to the Colorado Supreme Court.
The Colorado Supreme Court’s Decision
Required Location Specificity in No-Injury Analysis
The Colorado Supreme Court began its opinion by noting that it historically:
. . .has looked to both context and case-specific facts when approaching the question [of] whether an applicant must identify an exact location for a diversion structure to obtain a conditional water right. Firestone at ¶ 41.
These decisions, which did include several cases in which quarter-quarter sections were sufficient for a water court to make a finding of non-injury, were distinguishable from Firestone’s application. Specifically, those cases involved either absolute water rights or surface water rights and thus the depletions, in both timing and location, were more readily discernable.
In this case, the water court found, and the Colorado Supreme Court refused to overturn, that the case-specific facts regarding the proposed wells were not sufficient to allow the court to accurately determine whether the proposed plan for augmentation would be sufficient to prevent injury. The Colorado Supreme Court noted that by doing this the water court did not create a bright line rule that an applicant must construct a well before obtaining the conditional groundwater right and accompanying plan for augmentation. Instead, water courts are obligated to evaluate each application on a case-by-case basis to determine whether the evidence presented by an applicant is sufficient to permit the water court to make a “reasonably accurate” determination of non-injury. City of Aurora, 105 P.3d at 616-17.
Firestone argued that the water court’s decision finding that the proposed locations were not sufficient to allow an accurate URF analysis adopted a new “precisely accurate” standard rather than the “reasonably accurate” standard under City of Aurora. The Colorado Supreme Court upheld the water court’s findings primarily based on the above-described case-by-case analysis standard. It is possible that an applicant could prove no-injury without exact location information, but in this case the water court found that Firestone did not meet that burden. The Supreme Court agreed and declined to overturn the water court’s finding that Firestone’s plan for augmentation, as plead, did not sufficiently demonstrate that it would replace out-of-priority depletions in the proper place, timing, and amount.
Retained Jurisdiction
The Colorado Supreme Court then turned to Firestone’s argument that it should be granted the conditional water rights and then allowed to refine the URF calculations under the water court’s retained jurisdiction. In essence, Firestone asked the water court to grant the conditional water rights and then later refine and update the URF calculations to align with the actual construction. The water court refused to allow this provision and held that it would be an impermissible use of the water court’s powers of retained jurisdiction.
The Colorado Supreme Court agreed with the water court’s ruling, relying on Buffalo Park which held that the:
. . .[i]ntroduction of reliable evidence of the quantity, time, and location of depletions and the legal availability of replacement water is the responsibility of the applicant and cannot be postponed to occur under retained jurisdiction. 195 P.3d at 685 (citing City of Aurora, 105 P.3d at 616-17).
The Supreme Court reaffirmed that an applicant must meet the burden of showing no-injury “at the time it applies for a conditional groundwater right.” Firestone at ¶ 52 (emphasis in original). Instead, the Court ruled, again citing City of Aurora “the purpose of retained jurisdiction is to reconsider injury once an augmentation plan is operating, not to prove depletions or prove injury for the first time.” Id. (quoting City of Aurora, 105 P.3d at 616). Because Firestone failed to prove injury at the time of the application, the Supreme Court upheld the water court’s decision dismissing the three well fields and declining to allow a future no-injury analysis under the water court’s retained jurisdiction.
Conclusion and Implications
The Firestone decision reaffirmed the strict no-injury standards that an applicant must prove when obtaining approval of a plan for augmentation. This analysis must be done on a case-by-case basis and may require an applicant to further specify the location of proposed conditional water rights. The locations may not need to be “precisely accurate” but must be “reasonably accurate” such that a water court may properly analyze the URF calculations or other engineering demonstrating the location, timing, and amount of proposed depletions. The Colorado Supreme Court further reaffirmed its holdings in Buffalo Park and City of Aurora that the water court’s powers of retained jurisdiction are only to be used for evaluating a plan for augmentation that has already been approved and is operational. Retained jurisdiction may not be used to kick the proverbial can down the road and avoid an applicant’s burden of proving no-injury at the time it applies for conditional water rights.
Although this decision does not necessarily create new law, it reinforces that the burden to prove non-injury in water rights adjudications remains firmly with the applicant, and that the water court can and should demand clarity, precision, and credible modeling before approving conditional water rights and a plan for augmentation. This opinion offers valuable guidance to municipalities and other water rights holders that are planning future water projects and do not yet have exact information about the proposed project. The Firestone decision does not necessarily place a greater burden on future applicants but rather confirms that applicants for new conditional water rights and plans for augmentation must be fully prepared to conclusively prove that the new project will not cause injury to senior water rights. The Court’s opinion is available here: https://www.coloradojudicial.gov/system/files/opinions-2025-05/24SA109.pdf
