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used for public water supply for the Town of San Luis aze completed within the Alamosa Formation. The Servilleta Formation is exposed within the San Pedro Mesa southwest of the town and the bluff to the northwest of town; this unit also underlies the Alamosa Formation in the area. The Santa Fe Formation is present below the mesa and to the east of town along the base of the Sangre De Cristo Mountains as well as below the Alamosa and Servilleta formations in the area. The Servilleta and Santa Fe formations are not sources of ground water for domestic or irrigative uses due to the fine-grained nature of the deposits that encompass these units (ie., volcanic tuffs, siltstones, claystones, etc.) These units do, however, provide low hydraulic conductivity boundaries where these formations are in contact with the Alamosa Formation and, therefore, do have an effect on the local ground-water flow regime near the Town of San Luis. At the base of the Sangre De Cristo Mountains and along the drainages emanating from this front, alluvial fan deposits are present and act as zones of ground-water recharge due :o their high hydraulic conductivity. Also, minor alluvial aquifer systems aze developed along the larger drainages on the plains. The general ground-water flow patterns in the area within the Alamosa Formation will be in a westerly direction from the Sangre De Cristo Mountains towards the central portion of the San Luis Valley. However, neaz the Town of San Luis the ground-water flow regime is expected to be controlled by the presence of the Servilleta and Santa Fe formations within San Pedro Mesa and the bluff north of town. It is anticipated that these low hydraulic conductivity formations will funnel ground-water flow from the north and east in a southwesterly direction under the town to join the ground-water flow regime that follows the drainage of Culebra Creel:. For example, it is expected that ground-water flow within the alluvium of the Rito Seco drainage would pass under the town and join the ground-water flow system within the Culebra Creek drainage and flow westwazd towards the central portion of the San Luis Valley. Attached to this letter is a summary of the permitted wells in the Town of Saz. Luis and vicinity based on the files of the Office of the State Engineer. Based on the discussion provided regazding the local hydrogeology and the total depth records where available for the local wells, it is evident that the ground-water system of choice for water usage in the area is the Alamosa Formation. This statement is consistent with the findings of vazious studies in the San Luis Valley that include this area. The records acquired indicate that there are two SLWSD wells used for public water supply for the Town of San Luis -one well is completed to 90 feet below land surface and the second is screened to a total depth of 300 feet below land surface. Records for the deeper well indicate an extensive open interval from 83 to 300 feet below land surface; information was not obtained on the open interval of the shallow well. Of the SEO records which provided total depths for wells in the area most have a total depth of less than 100 feet below land surface. The depth to water where provided was shallow, commonly less; than 20 feet below land surface. THE CONCERN TO BE ADDRESSED It is my understanding that the greatest concern of the locals for the protection of their drinking water is contamination that might emanate and migrate from mining activities at the