- 28 - 



Three-month boron FWCs for the period of record are shown in Figure 22 . 

 The short term objective of 3.5 mg/L boron was not exceeded for the 

 period 1975-1990. The similarity in shape between the TDS and boron 

 plots (Figures 15 and 22) is a strong indication of the significance of 

 discharge in FWC functions. 



from sample analysis 



x from regression 



l_j I i I i I i_J i I L. 



1 974 1 975 1 976 1 977 1 978 1 979 1 980 1 981 1 982 1 983 1 984 1 985 1 986 1 987 1 988 1 989 1 990 



Year 



Figure 22. — Three-month moving, flow-weighted boron concentration 

 for East Poplar River at International Boundary. 



The five-year boron FWCs, displayed in Figure 23, remained well below the 

 long-term objective of 2 . 5 mg/L boron. From mid-1988 to the end of 1990, 

 there was a slight increase in the five-year boron FWC. As was the case 

 with TDS, the five-year calculations for boron were significantly 

 influenced by the relatively large discharge during the spring of 1985. 



