- 14 - 



Three-month boron FWCs for the period of record are shown in Figure 

 7. The short term objective of 3.5 mg/L boron has not been exceeded 

 in the period 1975-1987. (The similarity in shape between the TDS 

 and boron plots is an indication of the major influence of discharge 

 in FWC functions.) 



The five-year boron FWCs appearing in Figure 8 remained well below 

 the long term objective of 2.5 mg/L boron. As was the case with TDS, 

 the five-year calculations for boron were significantly influenced by 

 high discharge during the springs of 1982 and 1983. 



The relationship between boron and specific conductance at the East 

 Poplar River sampling location during the period 1975-1988 is de- 

 scribed by the equation: 



boron = (0.00148 x specific conductance ) - 0.285 

 (R 2 =0.73, n=350) 



Other Water Quality Variables 



Table 4 contains the multi-purpose water quality objectives for the 

 East Poplar River at the International Boundary, recommended by the 

 International Poplar River Water Quality Board to the IJC. 



One exceedence of the multi-purpose objectives occurred in 1988. 

 The 4.0 mg/L objective for dissolved oxygen was exceeded on July 15, 

 1988, when 3.6 mg/L was measured by the USGS. The sample was collected 

 at 8 a.m. in mid summer when oxygen depletion by heavy algae growth 

 would be expected. A reading by Environment Canada 9 days earlier at 

 mid day had indicated 7.5 mg/L dissolved oxygen. A review of 

 Saskatchewan Power Corporation automonitor data has shown that very 

 low dissolved oxygen was present during the first half of July, with 

 concentrations on occasion dropping as low as 1.0 mg/L. A number of 

 winter measurements by both the USGS and Environment Canada were in 

 the 5.0 mg/L range, just above the objective. 



