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<br />Table 1. Sample dales and analyses for slles AR34.5 and AR31.0, April 1994lhrough March 1995-Conlinued
<br />[X. sample collected and analyzed; -, no specific sample time because sample was composited from several discrete samples collected during a st~
<br />NS. sample nol analyzed for dissolved metals)
<br />Sample Sample Tolel- Dissolved- Sample Sample Total. Dissolved.
<br />melel metel metaJ metel
<br />dele Ume enelyses enelyses dale Ume analyse. anely_
<br /> SITE AR31.C1--C.nUnued
<br /> POlt~pe.k .nowmelt runoff:
<br />06/09/94 1020 X X 06/22/94 1005 X X
<br />06/16/94 0710 X X 06/27/94 1440 X X
<br /> Summer 8ow:
<br />07/21/94 0915 X X 08/26/94 1200 X X
<br />07/27/94 1425 X X 09/09/94 0845 X X
<br />08/1 0/94 1005 X X 09/26/94 1600 X X
<br />08/16/94 0915 X X
<br /> Bile flow:
<br />10/12/94 1120 X X 01/24/95 0930 X X
<br />10126/94 1030 X X 02/22/95 1420 X X
<br />11/21/94 1430 X X 03/14/95 1030 X X
<br />
<br />Instantaneous streamflow, water-temperature,
<br />pH, dissolved-oxygen, and specific-conductance data
<br />collected during the study are available from the
<br />u.s. Geological Survey; results of analyses of the
<br />metal and trace-element data collected during the
<br />study are available from the U.S. Environmental
<br />Protection Agency. The mean daily streamflow
<br />data used in this report are available from the
<br />Colorado Division of Water Resources.
<br />
<br />Acknowledgments
<br />
<br />The authors would like to express special
<br />thanks for the cooperation, interest, and support
<br />provided by James Hanley, U.S. Environmental
<br />Protection Agency, and by Harry H. Posey and
<br />James A. Pendleton, Colorado Department of
<br />Natural Resources, Division of Minerals and
<br />Geology. Thanks are extended to the following
<br />persons without whom the successful completion
<br />of this project would not have been possible:
<br />Craig Cotton, Colorado Division of Water Resources
<br />in A1amosa, Colorado, for providing streamflow
<br />data; and Roderick F. Ortiz, Charles M. Moore,
<br />Nicole Nelson, and Melinda Wright, U.S. Geological
<br />Survey, for data collection and processing.
<br />
<br />STREAMFLOW CHARACTERISTICS
<br />AND pH
<br />
<br />Streamflow in the upper Alamosa River Basin
<br />predominantly is derived from melting of snow that
<br />accumulates in the mountains between October
<br />and May. The largest streamflows occur between
<br />April and July during snowmelt runoff. Frequent
<br />summer rainstorms contribute substantially to
<br />summer flows. Downstream from Terrace Reservoir,
<br />streamflow is largely controlled by the quantity of
<br />water released from the reservoir to meet downstream
<br />irrigation demands. The streamflow hydro graphs
<br />for the study period for sites ARJ4.5 and ARJI.O
<br />are shown in figure 2. The annual streamflow
<br />hydrographs were divided into discrete flow
<br />periods. The flow periods were defined as follows:
<br />April I, 1994, through April 14, 1994, was defined as
<br />the early spring snowmelt period; April 15, 1994,
<br />through May 14, 1994, was defined as the pre-peak
<br />snowmelt period; May IS, 1994, through June 8, 1994,
<br />was defined as the peak snowmelt period;
<br />June 9, 1994, through July 14, 1994, was defined
<br />as the post-peak snowmelt period; July IS, 1994,
<br />through September 30, 1994, was defined as
<br />the summer-flow and storm-runoff periods; and,
<br />upstream from the reservoir, October I, 1994, through
<br />January 31, 1995, was defined as the base-flow period.
<br />
<br />6 AsMssment of Metal Treneport Into end Out of Terrace Reservoir, Conel.. County, Colorado, 0 () 316 3
<br />April 1994 Through March 1995
<br />
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