Laserfiche WebLink
Peter Foster and Jonah Howe, Wright Water Engineers Page 6 c <br /> Re: Gunnison West Gravel Pit SWSP, Amendment No. 1 <br /> December 12, 2025 <br /> United's pro-rata ownership of the Seventy-Five Ditch, the 4.33 cfs could irrigate up to 173 <br /> acres. The StateCU model with the Upper Gunnison High Elevation Calibration Coefficient <br /> was used to determine the historical consumptive use (HCU) for lands irrigated under the <br /> Seventy-Five Ditch, Priority No. 1. In addition, based on the decreed duty of water of 1 cfs <br /> per 40 acres of land, the Applicant has determined the historical consumptive use for the <br /> lands under the Seventy-Five Ditch as 1.7 acre-feet/acre, as shown on attached Table 3. <br /> Based on the average depth to groundwater of approximately five (5) feet below the ground <br /> surface, the historical consumptive use for subirrigation was reduced by fifteen percent <br /> (15%), resulting in an adjusted historical consumptive use value of 1.5 acre-feet per acre. <br /> The gravel mining operations at Gunnison West Pit have resulted in the dry-up of 30.9 acres <br /> of the mining property outside of the pit ponds, as shown on attached Figure 2. Applying the <br /> adjusted HCU value of 1.5 acre-feet/acre to this area produces an HCU credit of 45.6 acre- <br /> feet/year, which exceeds the estimated depletions of the gravel pit operations of 21.7 acre- <br /> feet/year during the term of this SWSP. <br /> Call Analysis and Return Flows <br /> The only major water right in the vicinity of Gunnison West is the Gunnison River <br /> Whitewater Course. The Gunnison West irrigated lands and associated return flows are <br /> located downstream of this Recreational In-Channel Diversion water right. The historical <br /> calling water rights downstream of the Gunnison West operation are the Gunnison Tunnel <br /> and the Redlands Power Canal. In 2002 the Gunnison Tunnel placed a call from July 7 to <br /> September 19 and from September 25 to September 27. The Redlands Canal has not <br /> historically placed a call, but could potentially place a call when stream flows are not <br /> adequate to meet their water rights. The Seventy-Five Ditch, Priority No. 1 water right is <br /> senior to both Gunnison Tunnel and Redlands Canal water rights. The Applicant asserts, per <br /> discussion with Division 4 Engineer Bob Hurford, that the historical call period on the <br /> Gunnison River should be expanded by adding December through April to the presumed call <br /> period of July through September. Adding April introduces the expectation of adding <br />