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<br />~ee,' e- <br />1939 .. i'..::Ui\;1iN;. En.- -- <br />., -, .--:,-., "rr-.,',~-rc- ~ '0 <br />. . '._ _, i,,....~ )__ .-..) /'~. '.".,-. <br />. .", "h.. ~~... . ,<_. . ..... <br />resents the greatest accumulation each year (Bums. 1985). The ranK-.suit!.test results.'0f1he-1964- 74. and 1975-94 <br /> <br />-APril 1 snowpack data indicate no significant difference at any site for the two periods (table 3). Therefore. differ- <br /> <br />ences in native runoff from snowmelt probably do not account for the differences in streamflow for the two periods <br /> <br />at Canon City. <br /> <br />Table 3 near here. <br /> <br />The transmountain imponation of Colorado River Basin water into the Arkansas River Basin has occurred <br /> <br />since the late 1800's. The imported water has been used to meet mining. agricultural, municipal, and industrial water <br /> <br />needs. Some of the imported water is divened directly into the mainstem of the upper Arkansas River, while some <br /> <br />of it is diverted out of the upper basin via closed conduit flow. During 1964-74, prior to the completion of Pueblo <br /> <br />Reservoir, the median annual volume of water that was imported into the Arkansas River was about 62,900 acre-ft <br /> <br />(fig. 6). The median annual volume of imported water increased significantly (p = 0.01) to about 103,000 acre-ft <br /> <br />Wuring 1975-94 (fig. 6). This increase is attributable to the Fryingpan-Arkansas Project importations, which began <br /> <br /> <br />in 1972. The increased imponation of western-slope water and the release of this water from storage during other- <br /> <br />wise low-flow months probably accounts for the increase in discharge at Canon City during October-April. <br /> <br />Figure 6 near here. <br /> <br />The significance of the discharge trends with respect to water quality are evident in the specific-conductance <br /> <br />dara (fig. 7). Although there is a 13-year gap (1977-89) in the specific-conductance record (fig. 7), the data do pro- <br /> <br />vide important information about the quality ofwarer that entered the lower basin before and after the construction <br /> <br />of Pueblo Reservoir. A visual assessment of the data indicates that the range of specific-conductance values (130- <br /> <br />380 IlS/cm) was relatively constant throughout the 3 I-year period (fig. 7). What is not readily apparent in figure 7, <br /> <br />is that the median specific conductance decreased about 19 percent from 307 IlS/cm in 1964-1974 to 250 IlS/cm in <br /> <br />1990-94. Boxplots of monthly specific-conductance data for the 1964-74 and 1975-94 periods, indicate that after <br /> <br />.974 specific conductance tended to decrease during most low-flow months and increase during the late summer <br /> <br />19<:1... <br />