- 33 - 



1990 SURFACE WATER QUALITY 



East Poplar River 



Total Dissolved Solids 



Analyzed TDS concentrations in 1990 ranged from 783 mg/L (April 10) to 



1,110 mg/L (May 11). 1990 TDS results are presented in Figure 25. As 



mentioned in the 1981-90 section, there were no exceedences in 1990 of 

 either the three-month FWCs or the five-year FWCs for TDS. 



1200 



1100 - 



1000 - 



E^ 900 - 



CO 

 Q 

 >- 800 



700 



600 



• • • 



1990 



J J A 

 Month 



D 1991 



Figure 25. — TDS concentrations for 1990 grab samples from 

 East Poplar River at International Boundary. 



Boron 



During 1990, boron concentrations in the East Poplar River at the Inter- 

 national Boundary varied from 1.6 mg/L (April 10) to 2.1 mg/L (May 11) 

 (Figure 26) . In 1990, boron did not exceed either the three-month FWCs 

 or the five-year FWCs. 



