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<br />00193D <br /> <br />650 <br /> <br />J, ENVIRON, QUAL., VOL. 27, MAY-JUNE 1998 <br /> <br />loads were adjusted for flow prior to analysis of dis- <br />solved-solids trends. Variability that could affect trend <br />results remains after the flow-adjustment process, as <br />shown in flow-adjusted annual loads for the site Roaring <br />Fork River at the mouth for 1970 to 1993 (Fig. 7). Similar <br />results occur at the other sites in the basin and also for <br />flow-adjusted periodic dissolved-solids concentrations <br />and monthly loads. After streamflow adjustment, there <br />still are possible effects on trends from channel evolu- <br /> <br />tion and hydrologic variation, changes in water quality <br />and discharge of groundwater springs and seeps, sample <br />size and period of record of dissolved-solids data, and <br />changing land-use practices. <br /> <br />Channel Evolution and Hydrologic Variation <br /> <br />One possible explanation for the downward trends in <br />dissolved-solids concentrations and monthly and annual <br /> <br /> <br />Water Years 1970 - 93 <br /> <br />Water Years 1980 - 93 , <br /> <br />Water Years 1986 - 93 <br /> <br />EXPLANATION <br /> <br />10 <br />~ Downward Trend <br />10 <br />A Upward Trend <br />10 <br />. No Trend <br /> <br />. Salinity-Control Projects <br /> <br />o 20 40 MILES <br />I .'. . <br />o 20 40 KILDMETERS <br /> <br />Fig. 5. Trends in Bow-adjusted monthly dissolved-solids loads in the Colorado and Gunnison River Basins, water years 1970-1993, 1980-1993, <br />1986-1993. Number adjacent to symbol designates site number listed in Table 1. Data for Sites 9 and 13 from Butler (1996). <br />