17 



The long-term 5-year moving flow-weighted mean concentration is presented 

 in Figure 5b. Although only the irrigation season (March to October) was of 

 concern to the IJC, all yearly values are included in Figures 6 & 7, in order 

 to better present long term trends in the data. 



The 5-year moving average boron concentration does not at any time during 

 the period of record, exceed the 2.5 mg/L recommended long-term 

 objective. The maximum value for observed is 1.47, recorded for the 

 5-year period July 1976 to June 1981 (plotted at the January, 1979 

 location in Figure 5b). The large change in the plot, from 1.35 to 0.94 mg/L 

 Is attributed to the very high flows of April 1982 (see discussion for TDS) 

 coupled with a low boron concentration. 



Other Water Quality Characteristics 



Table 3 shows the multi-purpose water quality objectives recommended by 

 the International Poplar River Water Quality Board to the IJC. The number 

 of samples collected for each parameter is also shown. No exceedences of 

 the recommended multi-purpose objectives occurred in 1985. 



Environment Canada data indicate that the dissolved mercury content of the 

 East Poplar River was at or below the analytical detection limit of 0.02 ug/L. 



Cookson Reservoir 



There are no trends yet evident in the water quality of Cookson 

 Reservoir. Boron and TDS concentrations remained below 2.0 and 1000 ug/L, 

 respectively. Dissolved oxygen levels remained high. The data provided 

 by Saskatchewan Environment do not exceed the objectives for the East 

 Poplar River at the International Boundary (Table 3), 



