concurring in part and dissenting in part:
I concur with the majority that the applicants are precluded from using urban runoff as part of their augmentation plans to compensate for post-pumping depletions of not nontributary ground water from the Denver aquifer. I agree that section 37-92-103(9), 15 C.R.S. (1990), prohibits a plan for augmentation from including “the use of tributary waters collected from land surfaces which have been made impermeable, thereby increasing runoff but not adding to the existing supply of tributary water.”
I do not join part IIB because I believe that we do not need to reach the issue of the timing of the runoff compared with the calls made by senior appropriators. The opinion holds that the water court erred in admitting evidence of runoff and that is dispositive. See Maj. op. at 498, 504, 506, 510. The question of timing is not an independent ground of decision because a favorable ruling on that issue could not result in a finding of no injury. In my view, the timing issue should not be addressed and part IIB of the majority is dictum. Twilley v. Durkee, 72 Colo. 444, 454, 211 P. 668, 671 (1922); see also United *511States v. Jesse, 744 P.2d 491, 502-03 (Colo. 1987).
A timing question arises in this case because of what the majority describes as the “fluctuating and unpredictable nature” of urban runoff resulting from precipitation. Maj. op. at 507. The primary source of the runoff water included in the Castle Meadows and Castle Pines augmentation plans is water from rain and snow. As we know, precipitation in Colorado is infrequent and even nonexistent at times. This fact leads to what the majority calls a “timing discrepancy”. Maj. op. at 507. Post-pumping depletions and the corresponding need for augmentation will occur one hundred or more years in the future.1 The applicants’ evidence does not correlate the times in the post-pumping era when rain will fall and accrue to the South Platte River basin with the times when senior water rights holders will make calls for South Platte River water. Accordingly, the majority finds, such precipitation water cannot be used to replace water that would otherwise be in the stream. But even if the applicants managed to solve the timing problem by, e.g., impounding the water to make it available on demand, approval of the augmentation plans still would be denied because the water is runoff and statutorily cannot be used in an augmentation plan. Thus, I believe the timing discussion is fruitless.
In other cases, however, an applicant for a plan of augmentation attempting to prove non-injury first must quantify the amount, timing, and location of water accruing to a stream by proof that is more probable than not. Then, the applicant must show that this water will replace the applicant’s out-of-priority draws from the stream. See Maj. op. at 506-507. If the water court finds that such showing has been made, and the water court’s finding is supported by the evidence,2 we should affirm the ruling. I must differ from the majority here because the language used in part IIB seems to invite objectors and water courts to demand an impossibly exact standard of proof to show non-injury.
For these reasons, I do not join in part IIB of the majority opinion.
. Our first decision in this case noted evidence of post-pumping depletions for a period of two hundred years. Danielson v. Castle Meadows, Inc., 791 P.2d 1106, 1114 (Colo.1990).
. Here, neither Castle Pines nor Castle Meadows countered the State Engineer’s arguments regarding the timing issue.