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J} ~ Commercial wells are most likely to pump from an aquifer hydrologically connected to the Animas River. Even if a commercial well were pumped for only 12 hours per night, the impact on the Animas River through various geologic formations could be distributed continuously over a much longer period, including the 12 hours during the day. The Glover model is used to evaluate the time it takes water pumped from a well on a certain day to impact a river. This time varies for each well and is dependent on the distance of the well from the river, its depth, and the type of geologic formations. The critical compom:nt, the water flow through the various geologic formations, could reduce water in the Animas River continuously, not just during the 12 night time hours. Because of this potential impact on the RICD, it would not be possible for an existing undecreed or new commercial well to pump without impacting the RICD. Therefore, the RICD could cause curtailment of existing cOInmercial wells and preclude new water I depletions in the Animas River basin. \-. .-____ c:---d CL:J?-IJ ~J: ~1~ldr~ The theoretical use of water available only at night raises a significant concern about DWR's ability to administer night time water use. Timing upstream diversions in order to avoid a daytime impact to the RICD may be impossible, not only for commercial wells. It is unlikely that a diversion from the Animas River near Silverton into a reservoir or a treatment plant for domestic use can be timed so that there is decreased flow at the RICD only at night. Such timing would depend on the amount of flow in the river and may, therefore, be impossible to estimate the time a diversion in Silverton would impact the RICD. Unless a surface diversion were immediately upstream of the RICD inorder to accurately predict when the impact would reach the RICD, the water available at night cannot be practically utilized. Commercial wells were shown as the most glaring example of how the RICD would preclude new Compact depletions; however, this would also apply to other types of diversions, storage and off stream pond evaporation. The RICD would not just preclude new uses but would preclude existing undecreed commercial wells, ponds, and diversions of which there may as many as 100. Based on the examples above, the RICD would precJlude and impair Colorado's ability to use Compact depletions which would occur without the RICD. Section 1.B.3 Durango Compact Impairment Methodo}Qgy The W.W. Wheeler report, entitled City of Durango Boating Park Hydrology Study, dated February 2006, addresses the issue of compact impairment by simply reporting that an "informally convened ad hoc Endangered Fish Flow and Colorado River Compact Water ~:1 / Development Workgroup" (Workgroup) ~v't Workgroup concluded that the CWCB could potentially appropriate instream > ~~ j;"" ~' flow rights in the San Juan River basin that would command all of such surplus ;",/~ ~ j water ~ithout adversely affecting Colorado's ability to fully utilize its compact d tll/l ~.: I apportIOnment. , - tv (t/t1 r;:u' Je'l~)QI -to;f wh I~ ~ J\(l P 171# 1J.,y . ~ /j 'p J r" JI rtJ.t>.'~ Yl ~ I. v~'/ ~ .~&-l (Jt.vl Y \ rJ r,tl e-I ()1 I ~~~ . i;t? ~