- 22 - 



Each point represents the flow-weighted concentration for a 5-year 

 period, with 2 1/2 years on either side of the plotted point. It 

 should be emphasized that the data base is comprised of all data 

 collected during the 12 months of all years. 



Total Dissolved Solids 



The proposed short-term objective for TDS is 1,500 mg/L. A plot of 

 the 3-month moving flow-weighted concentration is shown in Figure 4a. 

 No exceedences of this objective have been observed over the 1975-85 

 period of record. The relationship between TDS and specific conduc- 

 tance generated from the data collected to the end of 1986 is as 

 follows: 



TDS = [0.640 X specific conductance] + 10.533 (R^ = 0.87) 



The long-term, 5-year moving flow-weighted concentrations for TDS are 

 shown in Figure 4b. TDS concentrations calculated for the 5-year 

 periods ending in 1986 remained below the proposed long-term objective 

 of 1,000 mg/L. Analyzed TDS concentrations during 1986 ranged from 

 725 mg/L (March 7) to 1,223 mg/L (November 13). Analyzed TDS and 

 regression-generated TDS for the period of record are presented in 

 Figure 5. 



Boron 



During 1986, boron concentrations in the East Poplar River at the 

 International Boundary varied from 0.85 mg/L (March 7) to 2.65 mg/L 

 (November 13). The moving 3-month flow-weighted boron concentrations 

 for the period of record are shown in Figure 6a. The short-term 

 objective of 3.5 mg/L boron has not been exceeded in the period 

 1975-86. The moving 5-year flow-weighted concentrations are presented 

 in Figure 6b. As with TDS, the 5-year weighted concentrations 

 remained well below the proposed long-term objective of 2.5 mg/L 

 boron. 



