- 21 - 

 SURFACE WATER QUALITY 



East Poplar River 



The 1981 report by the IJC to Governments recommended: 



Foi the March to October period, the maximum flow-weighted 

 concentrations should not exceed 3.5 mg/L for boron and 

 1,500 mg/L for total dissolved solids for any three con- 

 secutive months in the East Poplar River at the Interna- 

 tional Boundary. 



For the March to October period, the long-term average of 

 flow-weighted concentrations should be 2.5 mg/L or less for 

 boron, and 1,000 mg/L or less for total dissolved solids 

 in the East Poplar River at the International Boundary. 



Comparison of the East Poplar River water quality with the proposed 

 short-term objectives for total dissolved solids (TDS) and boron is 

 tested by calculating the 3-month (90-day) moving flow-weighted 

 concentration for each, advancing one month at a time while dropping 

 the first month of the three-month period. Prior to 1982, this 

 comparison was based on instantaneous samples. Since the beginning 

 of 1982, daily TDS and boron concentrations have been computed from a 

 regression relationship with specific conductance. However, the data 

 from both instantaneous samples and from calculation of TDS and boron 

 are presented. 



The Poplar River Bilateral Monitoring Committee has adopted the 

 approach that, for the purposes of comparison with the proposed IJC 

 long-term objectives, the TDS and boron data are best plotted 

 graphically as a 5-year flow-weighted moving average which is 

 advanced 1 month at a time. 



