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on owner, location and use. Many of the well permits contain geologic information from the <br />well driller, including a log of geologic materials encountered during drilling, initial water levels, <br />well yield and well completion information such as well depth, well construction and screened or <br />open borehole intervals. There may be some wells listed in one database and not the other, so it <br />will be necessary to combine the databases during SPDSS implementation to obtain a more <br />comprehensive State listing of wells. <br />The third database is of geophysical well logs. This database is maintained by the SEO <br />Geotechnical Services Branch. It includes information on well permit number, location and <br />owner, formation boundaries, sand thickness, water level and types of logs available. This <br />database contains approximately 4,000 logs for the Denver Basin and Overlying Alluvium <br />Region. <br />Additional records are maintained by (1) water user groups within Water Division 1 and Water <br />District 47 including, but not limited to, agricultural user groups such as Groundwater <br />Appropriators of the South Platte (GASP), the Central Colorado Water Conservancy District <br />(CCWCD) and the Lower South Platte Water Conservancy District (LSPWCD), and <br />(2) municipal user groups such as Centennial Water District and Willows Water District. <br />Data available from the Colorado Oil and Gas Conservation Commission are primarily on oil and <br />gas test wells that were drilled during limited development efforts in the basin. Data collected on <br />these wells include geophysical logs, drillstem tests and geologic descriptions of formations <br />encountered. <br />3.7.2 Data Assessment <br />The available data are reviewed in terms of spatial coverage, length or period of record, <br />completeness and reliability. The assessment of the available well data are discussed below: <br />3.7.2.1 Spatial Coverage. Well data are available for all of Division 1 and Water <br />District 47 from the State in its well permits, water rights and geophysical log databases. The <br />databases cover all of the study area. <br />3.7.2.2 Period of Record. Well data is not a time series, so the period of record does not <br />directly apply. However, permit records are present in the State's permit database that <br />documents beneficial use dating back to 1858. <br />3.7.2.3 Completeness and Reliability. Well data vary greatly in content and quality. <br />The location information associated with the SEO well permit and water right databases are the <br />primary sources of information for well locations. Experience with the RGDSS has shown that <br />interpretation of this information and association of the well with the land irrigated by the well <br />can be difficult. The difficulties lie in the fact that original well locations are approximate and <br />many wells have been moved or replaced. Also, these records have been collected over a long <br />period where recording procedures have changed. A well permit may contain coarse geologic <br />and hydrologic information in the form of driller's descriptions of formations encountered, <br />p:data\gen\spdss~final report\chapter 3.doc 3 - l 6 <br />October 31, 2001 <br />