12 



The TDS objective has not been exceeded during the period of record. On inspection of the plot, it is 

 apparent that the three-month moving FWC has been increasing 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 2001 decreased from January through the spring runoff period and then 

 gradually increased through December to near the concentration observed at the beginning of 2001 . 



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

 in 2001 . The maximum monthly value calculated in 2001 was 948 mg/L, which is less than the previous 

 year maximum monthly value of 972 mg/L. 



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

 from January 1990 through December 2001 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. 



Note: There were no daily conductance data from September 13-30, 2001 and from October 1-24, 

 2001, inclusive. Therefore, the monthly representation samples used for September and October 2001 

 were the means calculated based on the recorded partial data for these two months. No gaps or voids 

 werefilled. 



The relationship between TDS and specific conductance applied to data collected from 1975 to 2001 is 

 as follows: 



TDS = (0.626 X specific conductance) + 31.542 

 (R^ = 0.85, n = 555) 



