600 



550 



500 % 



450'^ 



400 I 



350 •-. 



300 I 



o 



250 > 



v 



200 I 

 150 I 

 100 O 



- 50 



o> 1- 



Figure 3.3 Cumulative Volume Hydrograph of On-Demand Release. 



3.2.5 Surface-Water Quality 



The 1981 report by the IJC to Governments recommended: 



For the March to October period, the maximum flow-weighted concentrations should not exceed 3.5 

 milligrams per litre img/L) for boron and 1500 mg/L for TDS for any three consecutive months in the 

 East Poplar River at the International 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 1000 mg/L or less 

 for TDS in the East Poplar River at the International Boundary. 



For the period prior to 1982. three-month moving flow-weighted concentration (FWC) for boron and 

 total dissolved solids (TDS) was calculated solely from monthly monitoring results. Since the beginning 

 of 1982. the USGS has monitored specific conductance daily in the East Poplar River at the 

 International Boundary, making it possible to derive boron and TDS concentration using a linear 

 regression relationship with specific conductance. Thus, the three-month FWC for boron and TDS for 

 the period 1982 to 2002 was calculated from both the results of monthly monitoring (water-quality 

 samples collected by both Canada and the United States) and the statistical analysis of daily specific 



