12 



The total dissolved solids 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 1 997, 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 1998 and remained lower in 1999. 



The five-year moving FWC for TDS (Figure 3.6) did not exceed the long-term objective of 1000 

 mg/L in 1 999. The maximum monthly value calculated in 1 999 was just under 989 mg/L, which is less 

 than the previous year maximum monthly value of 1014 mg/L. 



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

 from 1989 to 1 999 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 1999 

 is as follows: 



TDS = (0.626 X specific conductance) + 31.542 

 (R^ = 0.85, n = 555) 



