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<br />'. <br /> <br />U,S. GEOLOGICAL SURVEY <br />Project Proposal-- May 8, 1998 <br /> <br />A. TITLE: <br /> <br />Evaluation of high ground-water levels in the Arkansas River Valley near La Junta, Colorado <br /> <br />B. LOCATION: <br /> <br />The location for the study is in the Arkansas River Valley in Otero County, near La Junta Colorado. <br />Specifically the study area includes the floodplain of the Arkansas River and extends from the Fort Lyon Canal <br />headgate, northwest of La Junta, to Bent's Fort, northeast of La Junta, a distance of about 10 river miles (fig 1), <br /> <br />C. PROBLEM: <br /> <br />. <br /> <br />During the past 20 years, the water table in the alluvial aquifer in the Arkansas River Valley between the Fort <br />Lyon Canal headgate and Bent's Fort in Otero County, Colorado has risen.. flooding basements, damaging <br />homes, and water-logging cropland, A study done in 1986-87 by the U.s. Geological Survey in cooperation <br />with the North La Junta Conservancy District (Watts and Lindner-Lunsford, 1992) determined that the rise in <br />water table near La Junta, Colorado was caused by a number of factors, but was primarily due to increased <br />leakage from the Arkansas River and Fort Lyon Canal in combination with decreased ground-water pumpage, <br />Another important factor identified as affecting the high water table was the aggradation of the channel of the <br />Arkansas River and the accompanying rise in river stage, which caused a rise in ground-water levels near the <br />river. Reportedly, the area affected by the high water table has recently become more extensive and has <br />resulted in additional problems, <br /> <br />D. OBJECTIVE: <br /> <br />The objectives of the study are to provide information that will document current high water-table conditions <br />in the study area and identify any time trends that may be present in historical ground-water conditions. <br />Several other data, described in the specific objectives below, that address potential causative factors for high <br />water table conditions will be evaluated to determine what relation they might have to any trends in historical <br />ground-water conditions, Although the study is designed to investigate potential causative factors for high <br />water table conditions in the study area, it is beyond the scope of the study to evaluate management scenarios <br />to remediate the high water-table conditions. The specific study objectives are: <br /> <br />1. To map ground-water levels in the study area based on a contemporary (1999) set of water level measure- <br />ments in about 50 wells. <br /> <br />2. To determine if the elevation of the ground-water table in the study area has a trend in time, based on avail- <br />able ground-water level measurements. <br /> <br />3. To determine if the Arkansas River and major tributaries and the Fort Lyon Canal, have experienced any <br />changes in discharge that may be related to increases in ground-water levels. <br /> <br />4, To determine, based on available data, if there are trends in either the amount of water stored as part of the <br />winter water storage program, or Fryingpan-Arkansas Project water, or both, for diversions to the Fort Lyon <br />Canal made during the irrigation season. <br /> <br />. 5. To determine if there are trends in ground-water withdrawals used for irrigation in the study area, <br /> <br />6. To determine if the local base level of the channel of the Arkansas River is increasing. <br />