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<br />,""1 l"!" 'I."
<br />40"U
<br />
<br />were collected for chemical analyses from near the res-
<br />ervoir surface and from near the reservoir bottom using
<br />a 4-L, nonmetallic, 2-ft-Iong water-sampling bottle,
<br />The near-surface samples were collected at the Secchi-
<br />disk depth, and the near-bottom sample was collected
<br />about 3 ft above the reservoir bottom. The near-surface
<br />samples were collected to characterize conditions in
<br />the photic zone, and the near-bottom samples were col-
<br />lected to characterize conditions in the hypolimnion.
<br />Samples collected for chemical analyses were treated
<br />and preserved using methods described in Feltz and
<br />others (1985), except samples treated onsite for analy-
<br />ses of nitrogen were not preserved with mercuric chlo-
<br />ride. Mercuric chloride was not added to the nitrogen
<br />samples analyzed by the Pueblo Board of Water Works
<br />Laboratory because of interference effects, The inor-
<br />ganic chemical constituents discussed in this report
<br />were analyzed using methods described by Fishman
<br />and Friedman (1985). The Pueblo Board of Water
<br />Works Laboratory analyzed samples collected for anal-
<br />yses of turbidity, major ions, dissolved and total nitro-
<br />gen species, and dissolved and total-recoverable trace
<br />elements. The U.S. Geological Survey National Water
<br />Quality Laboratory in Arvada, Colorado, analyzed
<br />samples collected for sulfate, dissolved and total phos-
<br />phorus species, radiochemical constituents, and total
<br />organic carbon. Analyses for radiochemical constitu-
<br />ents were made using methods developed by Thatcher
<br />and others (1977). Total organic carbon was analyzed
<br />using methods described by Wershaw and others
<br />(1983). The U.S. Geological Survey National Water
<br />Quality Laboratory also analyzed samples for all con-
<br />stituents that were collected for quality-assurance pur-
<br />poses (Edelmann and others, 1991).
<br />
<br />Sediment cores were collected for analysis of
<br />selected \race elements from reservoir sites using a
<br />4-ft-Iong, weighted, stainless-steeI4-in. corer that con-
<br />tained a plastic sleeve. The sediment cores were sub-
<br />sampled at the o--2-cm depth interval and the 4-6-cm
<br />depth interval for total-recoverable analyses of selected
<br />constituents by the Pueblo Board of Water Works Lab-
<br />oratory and for total analyses by the U.S. Geological
<br />Survey, Geologic Division Laboratory in Lakewood,
<br />Colorado. In addition, interstitial water was collected
<br />at discrete intervals and analyzed by the U.S. Geologi-
<br />cal Survey,
<br />
<br />Biological samples were collected for analyses
<br />of phytoplankton and chlorophy II a. Biological analy-
<br />ses were done by Chadwick and Associates of Little-
<br />ton, Colorado. Phytoplankton samples were collected
<br />from a single depth near the reservoir surface using a
<br />4-L, nonmetallic, 2-ft-long, water-sampling bottle.
<br />Phytoplankton samples were preserved using a
<br />37-percent fonnaldehyde solution. Phytoplankton
<br />
<br />density values are reported in cells per millililer. Chlo-
<br />rophyll a samples were collected from near the reser-
<br />voir surface and from near the reservoir bottom. The
<br />sampling depths were the same as the depths at which
<br />water samples were collected for chemical analyses.
<br />One to two liters of water were filtered through a
<br />0.45-Jlm filter; the filter then was frozen onsite using
<br />dry ice. Chlorophyll a was extracted in the laboratory
<br />using acetone. The analyses were made using the chro-
<br />matography and spectroscopy method (Britton and
<br />Greeson, 1989), and a correction was made for pheo-
<br />phytin (Chadwick and Associates, Littleton, Colo.,
<br />written commun., 1985),
<br />
<br />In addition to data collection on Pueblo Reser-
<br />voir, water samples were routinely collected from the
<br />Arkansas River upstream and downstream from the
<br />reservoir for analyses of inorganic chemical constitu-
<br />ents. Specifically, samples were collected from station
<br />07097000, Arkansas River at Portland (upstream sta-
<br />tion) and station 07099400, Arkansas River above
<br />Pueblo (fig. 1),
<br />
<br />Acknowledgments
<br />
<br />The authors would like to express special thanks
<br />for the cooperation, interest, and support provided by:
<br />Alan C. Hamel, James D. Hurt, and Brian B, Elson,
<br />Pueblo Board of Water Works; Jim Phillips, Edward W
<br />Bailey, and Patricia McGlothlin, Fountain Valley
<br />Authority; Charles L Thompson, Southeastern Colo-
<br />rado Water Conservancy District; Eugene M. Zamecki
<br />and Richard Hayes, Pueblo West Melropo/ilan District;
<br />Lee W. Simpson, David K. Simpson, and Donald Will-
<br />iams, SI. Charles Mesa Water District; and Jack Gamer,
<br />Bureau of Reclamation. The analytical chemistry work
<br />done by Julie A. Scaplo and Don A. Colalancia, Pueblo
<br />Board of Water Works, during the study is greatly
<br />appreciated.
<br />
<br />PHYSICAL CHARACTERISTICS
<br />
<br />The physical characteristics of the reservoir
<br />discussed in this section are thennal and specific-
<br />conductance stratification and mixing patterns, resi-
<br />dence times, water transparency, and distribution and
<br />transport of particulate matter. These characteristics
<br />affect many important chemical and biological pro-
<br />cesses within the reservoir.
<br />
<br />PHYSICAL CHARACTERISTICS 11
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