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~ ~ ~ <br /> <br />AREA DESCRIPTION <br />The study site was located at the end of County Road 29 5/8 <br />on the north side of the Colorado River east of Grand Junction, <br />Colorado. Gravel mining has created ponds throughout this area <br />and the study site is a gravel pit. The site is physically <br />separated from the Colorado River by a small dike, but <br />hydrologically it is connected to the River. Dominant upland <br />vegetation around the pond consists of Fremont cottonwood and <br />tamarisk. <br />Our first visit was on 2 June 1994 when the Colorado River <br />was at flood stage and the study site was inundated. There was <br />concern by several members of the visiting party on this date <br />that the high water flows in the river were threatening to breech <br />the dike between the river and the pond. If this happened the <br />configuration of the pond could have been significantly altered. <br />Our second visit occurred on 15 October when the Colorado <br />River was at base flow and water levels in the pond had dropped <br />considerably. Water depth in the main body of the pond was up to <br />5.5 feet. Using a hand held clinometer we estimated that the <br />water surface of the pond was approximately 0.44 feet higher than <br />that of the water surface of the Colorado River. This indicates <br />that there is not a complete connection between the pond and the <br />River. The pond most likely is fed by ground and surface return <br />flows from irrigation ditches to the north. <br />WATER QUALITY <br />Conductivity measurements were taken throughout the pond <br />area. The highest conductivity occurred on the eastern and <br />northern sides of the pond. This confirmed that the pond was <br />gaining water from the north and east. <br />One water sample was collected for laboratory analysis. No <br />heavy metals or selenium occurred in significant concentrations. <br />Most major cations and anions were present in modest quantities <br />indicating that there is not a salt problem at this site. As <br />with the Gunnison River at our study site near Delta, a <br />tremendous expanse of Mancos Shale outcrops in this region. Most <br />likely there are appreciably concentrations of salts liberated <br />from these shales. <br />1 <br />