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 declined slightly in 1 999 and remained lower in 2000. 



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

 in 2000. The maximum monthly value calculated in 2000 was 972 mg/L, which is less than the previous 

 year maximum monthly value of 989 mg/L. 



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

 from December 1989 to December 2000 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 applied to data collected from 1975 to 2000 is 

 as follows: 



TDS = (0.626 X specific conductance) + 31.542 

 (R^ = 0.85, n = 555) 



