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a a2 [j 14 The altitude below which stream are expected can be estimated. The given as: temperatures greater than the maximum stream temperature ZOOC limit (TMAX) is (4) T MAX=M+A . The TMAX of concern here is the ZOOC I imit. Because this temperature is never to be exceeded, it must, in fact, be measured as an instantaneous maxi- mum daily value. To be consistent with this approach, M and A in equation 4 also must be functions of maximum daily values. In reality, regional data for M and A in the Yampa River basin probably reflect measured temperatures somewhere between the daily mean and the daily maximum value (p. 10 and 16), and do not strictly satisfy this requirement. However, the following example illustrates the principle involved. In the Yampa River basin, A is estimated from A (fig. 4) to be 10.00C. Substituting this value and ZOOC for TMAX into equation 4 yields a value of 10.00C for M. Substituting this value. of M into equation Z yields an estimate of 4,950 ft (1,510m). The lowest point in the Yampa River basin is 5,100 ft (1,600 m) at the mouth of the Yampa River, so theoretically stream temperatures of ZOOC or greater should not be expected. It must be remem- bered, however, that the uncertainties involved in estimating M and A have not been considered in this anal~sis. The.e uncertainties easily account for the recorded temperatures that were greater than ZOOt. Major Inorganic Constituents and Specific Conductance Concentrations of major inorganic constituents frequently are correlated with specific conductance. In this study, lJnear, bivariate, least-squares regression equations relating major inorganic constituents to specific conductance (table 6) were developed on a regional basis using the data published by lorns, Hembree, Phoenix, and Oakland (1964). Site-specific regression equations for the Yampa River near Maybell, Colo., and for the Little Snake River near Lily, Colo. (table 7), were developed based on the data described on page 4. Two diTferent time periods were used for the site- specific regressions: One encompasses the entire period of recor.d at the time of the analysis (1951-75 water years); whereas, the other (1966c7Z water years) was that used by Steele, Gilroy, and Hawkinson (1974). The. latter, shorter period of record was chosen to eliminate any. time trends that might be affecting water qual ity. The appropriate site-specific regression equations (table 7) were appl ied to daily specific-conductance records available for the Yampa River near Maybell and the Little Snake River near Lily. For comparison purposes, the historical regional regression equations (table 6) also were appl ied at each site. Using a computer program documented by Steele (1973), daily loads and concentrations were estimated for the various chemical constituents, and monthly and annual discharge-weighted and time-weighted values were deter- mined. 26