2012-01-20_HYDROLOGY - C1981012 - Laserfiche WebLink

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INTEROFFICE MEMORANDUM To: Janet Binns From: Rob Zuber `R D Z Date: 20 January 2012 Re: New Elk (C -81 -012) - AVF Determination for South Fork of Purgatoire River As requested, I have performed a preliminary assessment of the existence of an AVF along the South Fork of the Purgatoire River, from Bandarito Canyon to the confluence with the Purgatoire River. River and Diversions Per the USGS county map, the South Fork of the Purgatoire River is a perennial stream. During the inspection on 19 January 2012 there was significant flow in the river. The Division of Water Resources maintains a database of diversions and water rights. This database indicates that the South Fork has (or has had in the past) several diversion structures including: the East Weston Pipeline, the Dorn Ditch, the Maes -Duran Ditch, and the Alejandro, Torres, and Vigil Ditch. The database indicates that the Dorn Ditch has been used for irrigation in the past. Soils Per the NRCS map (NRCS web survey at http://websoilsurvey.nrcs.usda.gov), the majority of soils in the South Fork valley, within a couple hundred feet of the stream bed, are soil type Molinaro Loam (Sw). This soil is characterized as follows by the NRCS: • Landform: Fan remnants, terraces, valley floors. • Parent material: Alluvium derived from sandstone and shale. • Available water capacity: High (about 9.3 inches). • Typical Profile: loam and clay loam to depth of 66 inches, with loam being the dominant type. As we have discussed, these characteristics indicate that Molinaro Loam can be characterized as alluvium. Other soils near the river are Bandarito Clay Loam (FuD) and Trujillo Loam (TmD). These two soil types also have the characteristics of alluvium. The soils where farming is practiced along the main stem of the Purgatoire River (see observations below) include Molinaro Loam and Mauricanyon Loam. Mauricanyon Loam has similar characteristics to Molinaro Loam.