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Table 9. Regression information used to determine dissolved-solids loads at sites 1-6, White River, water years 1975-88 [Ldsd, daily dissolved-solids load in tons per day; Qd. daily discharge in cubic feet per second] Logarithm lorm (basal 0) log l,jsd . a + b log Od Antilogarithm lorm l,jsd .10' oct" Cb Site Numbsr 01 samples COllfflclents Stsndard error (SE) (a) (b) Variance (s2) Bias correction factor (Cb) I 36 0.537 0.656 0.031 0.001 1.0025 Ldsd = 100.S37Qct".6361.0025 2 31 -0.036 0.855 0.038 0.001 1.0038 Ldsd = 10-O,036Qct".8551.0038 3 12 0.516 0.722 0.032 0.001 1.0028 Ldsd = 100.516<4\0.7221.0028 14 72 1.132 0.573 0.056 0.003 1.0085 Ldsd = 101.132Qdo.57J1.0085 24 20 0.971 0.630 0.051 0.003 1.0070 Ldsd = 100.971<4\0,6301.()(J70 35 23 0.934 0.691 0.091 0.008 1.0220 Ldsd = 100.934<4\0.6911.0220 36 54 0.988 0.690 0.080 0.006 1.0172 Ldsd = 100.98SQdo.6901.0172 IOctober 1975 to April 1982. 2May 1982 to September 1988. 3Waler years 1983-88. measured annual disso]ved-solids loads with annual stream discharge at sites 5 and 6 for water years 1983-88. Differences between regression values and measured values were Jess than 7 percent for the first pair of regr~ssions and Jess than 3 percent for the sec- ond pair of,regressions. The best estimated values of annual dissblved-solids loads at sites 5 and 6 for water years 1975,82 were obtained by using the regression estimates from the second regression pair. Estimated values of annual disso]ved-solids loads (water years 1975-82) and measured values of annual dissolved- solids loads (water years 1983-88) for sites 5 and 6 and measured disso]ved-solids loads for site 4 (water years 1975-88) ate correlated with annual stream discharge in figure 23. Selel;ted data for daily and annual dissolved- solids loads for the White River are listed in table 10. Statistical summaries of annual dissolved-solids loads for sites 1-6, the combined loads of sites 1 and 2 (site 3A), and contributions to annual dissolved-solids loads from river segments (river subbasins) of the White River are shown in figure 24. Annual dissolved-solids loads ranged from about 21,100 tons at site 2 to about 480,000 tops at site 6. The average annual dissolved- solids loads were least in the North Fork (site 1, about 54,000 tons) and South Fork (site 2, about 38,700 tons) and greatest at site 6 (estimated at about 348,000 tons). A comparison of annual loads of dissolved solids in the main stem of the White River (fig. 24) indicates that the average annual disso]ved-solids loads increased down- stream by about 250,000 tons between sites 3A and 6, Except for water years of very low stream discharge (1977) or years of high stream discharge (1983-86), annual contributions of disso]ved-solids loads from each subbasin in the White River Basin varied little. Comparisons of bar graphs of annual dissolved- solids loads (fig. 24) contributed from the river seg- ments (river subbasins) indicate that the North and South Fork Basins and the river subbasins between sites 3 and 5 were the principal sources of dissolved solids in the White River. A]though concentrations of dissolved solids in the North Fork (site 1) and South Fork (site 2) were small [generally from 1 ()() to 250 mgIL (Hutchison, 1975)], annual dissolved-solids loads were substantial because most of the water in the White River originates upstream from sites 1 and 2, Irrigation diversions from the White River upstream from site 3 probably caused an underestimation of dis- solved-solids loads between sites 3 and 3A and a nega- tive load in water year 1977 (fig. 24). Water from irrigation return flow, ground water, and the chemical action of surface runoff on poorly consolidated shales and siltstones probably accounted for mOst of the addi- tional increase in dissolved-solids loads from the sub- basins between sites 3 and 5. 48 Sediment Transport and Water-ouallty Characteristics and Losds, White River, Northwestern Colorado, Waler Vears 1975-88