Monthly average TDS concentrations derived from water-quality samples or the specific-conductance 

 monitor readings are shown in Figure 3.4. The TDS concentrations in 2005 ranged from 770 mg/L on 

 April 6 to 985 mg/L on October 15 which are below the proposed short-term objective of 1,500 mg/L. 

 The three-month moving FWC for TDS for the period of record is presented in Figure 3.5. The TDS 

 objectives have not been exceeded during the period of record. On inspection of the plot in Figure 3.5, it 

 is apparent that the three-month moving FWC increased gradually, year by year, up until the spring 

 runoff of 1997, when an exceptionally heavy snowmelt contributed sufficient water of low ionic strength 

 to the river and the reservoir to dilute the accumulated salts built up in the system. Dissolved-solids 

 concentrations in 2005 were similar to those recorded in 2004. In general, low spring runoff and higher 

 contribution from ground water have kept the TDS level close to the long-term objective of 1,000 mg/L. 



The five-year moving FWC for TDS (Figure 3.6) did not exceed the long-term objective of 1,000 mg/L 

 in 2005. The maximum monthly FWC in 2005 was about 954 mg/L, which is slightly higher than the 

 2004 maximum monthly value of 935 mg/L. 



The daily TDS values, as generated by linear regression from the daily specific-conductance readings, 

 for the period January 1990 through December 2005 are shown in Figure 3.7. The data show an abrupt 

 drop in TDS corresponding to the snowmelt runoff occurring during the spring of each year. 



The relationship between TDS and specific conductance based upon data collected from 1974 to 2003 is 

 as follows: 



TDS = (0.624613813 x specific conductance) + 35.1841527 

 (R^ = 0.84, n = 617) 



Note: The above equation was used to derive the missing TDS water-quality sample data for 2005. 

 These derived data are used in the current annual water-quality report. 



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