2011-04-19_HYDROLOGY - M1978287 - Laserfiche WebLink

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F Cheryl Signs, P.E. April 12, 2011 Seahorse Ranch West Pit and Vader Pit Combined Replacement Plan Page 3 of 7 According to the Applicant, the distance from the surface of the exposed ground water area to the Tomichi Creek was measured based on the down gradient extent of the exposed ground water surface (nearest point). For purposes of this SWSP, the method used to measure the distance to estimate the lagged depletions will be accepted, however any future SWSP must measure the distance from the exposed ground water surface area to Tomichi Creek based on the centroid of the exposed ground water surface. Replacements The proposed source of replacement water for the two gravel pits included in this SWSP is historical consumptive use credits associated with the dry-up of a portion of the lands previously irrigated by Griffing No. 2 and McCanne Nos. 2 and 3 Ditches. The lands occupied and surrounding the pits were part of a ranch straddling Tomichi Creek that was owned by the Vader Family. The ranch totaled about 1800 acres and it was historically irrigated by Griffing No. 1, Griffing No. 2 and McCanne Nos. 2 and 3 Ditches. The Griffing No. 1 is not included in this SWSP because this water was. changed in case no. 96CW267 and it's being used for augmentation purposes of Seahorse Pond Well. The crop demand for irrigated pasture was determined for the period from 1972 through 1997 using the modified Blaney-Criddle method with a soil moisture bank. This period was selected because of available diversion records and it contains dry, wet and average years. The growing season was also based on the diversion records with the earliest diversion beginning on April 15 and the latest occurring on October 22. Vader's interests in the Griffing No. 2 and McCanne No. 2 Ditches irrigated 129 acres north of Tomichi Creek. The northern area was combined because water diverted from Tomichi Creek for the two ditches could irrigate the same area. In addition, Vader's interest in the McCanne No. 3 Ditch irrigated 59 acre south of the creek. The ditch loss was assumed to be 30 percent for each ditch. United's projected ultimate demand was used to quantify the original decreed amounts that should be dedicated to this SWSP. These decreed amounts were used to allocate the daily diversion and the irrigated land attributable to those diversions. For the purposes of this SWSP, United will dry- up 84 acres under the Griffing No. 2 and McCanne No. 2 Ditches and 25.8 acres under the McCanne No. 3 Ditch. The historical consumptive use analyses for the Griffing No. 2 Ditch and McCanne No. 2 Ditch and the McCanne No. 3 Ditch are shown in Table 5 (attached). The sum of the average consumptive use for the three sources is 154.2 acre-feet per year. The sum of the dry year average is 143.8 acre-feet per year, which is sufficient to cover maximum projected demand of 143.58 acre-feet for April through October. In accordance with the letter dated April 30, 2010 (copy attached) from the Colorado Division of Reclamation, Mining, and Safety ("DRMS"), all sand and gravel mining operators must comply with the requirements of the Colorado Reclamation Act and the Mineral Rules and Regulations for the protection of water resources. The April 30, 2010 letter from DRMS requires that you provide information to DRMS to demonstrate you can replace long term injurious stream depletions that result from mining related exposure of ground water. The DRMS letter identifies four approaches to satisfy this requirement. The 4t' approach requires documentation to identify what water rights or other permanent water source will be dedicated to the SWSP to assure that all permanent depletions from either an unforeseen