13 



on 



a 



o 



Short-Term Objective (3.5 rug/L) 



V...K?!-. 





from sample analysis 

 from reeression 



1975 1976 1977 1978 1979 1900 1981 1982 1903 1984 1905 1986 1987 1988 1989 1990 1991 1992 1993 1991 1995 



Year 



Figure 3.7 Three-Month Moving, Flow-Weighted Boron Concentration for East 

 Poplar River at International Boundary. 



The 5-year FWCs for boron, displayed in Figure 3.8, 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 5-year FWCs 

 for boron. The 5-year FWCs for boron decreased from approximately 1.97 mg/L in 1993 to 1.88 

 mg/L in 1 994. The 5-year calculations for boron were influenced by discharge in the same way as 

 was TDS. 



