12 



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 were slightly lower in 2002 relative to those recorded in 2001; however, 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 2002. The maximum monthly value calculated in 2002 was about 943 mg/L. which is slightly less 

 than the previous year maximum monthly value of 948 mg/L. 



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

 from January 1990 through December 2002 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 1974 to 2002 is 

 as follows: 



TDS = (0.62518 x specific conductance) + 34.202 

 (R- = 0.84. n = 605) 



