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Data Assessment <br />• The RGWCD takes measurements of head in 15 confined aquifer wells. A number of <br />these wells have records back to 1983. This number is being increased to 50 wells <br />over the next two years. The USGS provides quality assurance and enters the data <br />into the USGS database. <br />The USBR regularly performs well monitoring as part of the Closed Basin Project. <br />These measurements include water level measurements in 82 observation wells, flow <br />measurements and level measurements in the 174 salvage wells, and the collection of <br />well water quality data. Of the 82 observation wells, 32 are dual completions that <br />allow head measurements in both the confined and unconfined aquifers. The USGS <br />provides technical assistance and quality assurance to this program. <br />• The USGS has drilled 16 unconfined wells in the Alamosa National Wildlife Refuge <br />and has trained U. S. Fish and Wildlife Service (USFWS) personnel to regularly <br />measure levels. The USGS provides quality assurance and enters the data into the <br />USGS database. <br />The USGS makes level measurements of 20 wells in Costilla County, provides <br />quality assurance, and enters the data into the USGS database. <br />These efforts provide important data that can be used in the RGDSS and in future studies. <br />However, it is worth noting that the spatial density of well measurements if assumed uniform <br />over the basin is still less than one well in each 50 square miles. There are large areas with little <br />or no reliable well data. There are other important areas where the existing data are insufficient to <br />describe the aquifer characteristics in sufficient detail. These areas include: <br />• Lower Conejos River along the north and west sides of the San Luis Hills <br />• The west of the Valley along the foothills of the San Juans and La Garita Hills <br />• Lower Saguache Creek area <br />• The heavily irrigated area between Center, Monte Vista, and Del Norte <br />• Trinchera Creek area <br />• The state line area southeast of Antonito <br />• The east-central part of the valley between San Luis Lake and the Great Sand Dunes <br />National Monument <br />There is also the issue that most of the existing wells, with the exception of the Closed Basin <br />Project monitoring wells, were drilled and completed as production wells. This generally means <br />that the well was completed or screened to a long depth, commonly 75 percent or more of the <br />total depth of the well. Head and hydraulic conductivity measurements collected in such wells are <br />composites for the entire open interval. Composite measurements are generally of limited <br />usefulness, but make up the majority of data that are available. Composite measurements <br />seriously compromise the usefulness of modeling efforts targeted at simulating the valley's <br />aquifers accurately. In addition, there are few confined aquifer wells that penetrate much below <br />1,500 feet, so there is comparatively little known about the aquifer characteristics below this <br />depth. <br />During interviews for the needs assessment, many of the respondents from the valley were <br />concerned about the available well data and also whether these data were sufficient to model the <br />valley's aquifer system. There were numerous discussions and requests for additional well data <br />collection. The consultant team and advisory committee have discussed additional well data <br />collection at length. It appears that for the RGDSS to be considered a success by the stakeholders <br />a454/report/fmaUdata. doc 7/2&~OS 3 -14 <br />