13 

 3.2.5.2 Boron 



During 1995, boron concentrations in the East Poplar River at the International Boundary 

 varied from 0.94 (9-May) to 2.2 mg/L (14-February, and 14-December) (Figure 3.7). 



Three-month boron FWC's for the period of record are shown in Figure 3.8. The short-term 

 objective of 3.5 mg/L was not exceeded for the period 1975-1995. It can be seen that the data 

 derived from grab samples and that derived from regression with specific conductance are 

 similar, with the highs and lows in some degree of correspondence. This indicates that the 

 regression generation of boron (and TDS) values is in general terms, a valid procedure. 



The five-year boron FWC's displayed in Figure 3.9 remained well below the long-term 

 objective of 2.5 mg/L. From mid 1993 to the end of the data period there is a distinct drop in 

 tlie computed values. 



The relationship between boron and conductivity at the East Poplar River sampling location 

 during the period 1975 to 1995 is described by the equation: 



boron = (0.0013 x specific conductance) - 0.092 

 (R^ = 0.61, n = 517) 



As shown in Figure 3.10, the straight line generated by the regression analysis of boron 

 (dependent variable) over time (independent variable) shows a positive slope of 0.025 

 mg/L/year. Again, as was the case with TDS, this is only a general indicator of a long-term 

 behaviour. It should not be considered a predictive tool, without a more detailed analysis of 

 weather, ground-water conditions, and conditions imposed by the power station. 



