27 



3 50 







0.30-0.56 0.56-0.82 0.83-1.08 1.09-1.34 1.35-1.60 1.61-1.86 1.87-2.12 2.13-2.38 2.39-2.64 2.65-2.90 



Boron (mg/L) 



Figure 20. — Distribution of boron concentrations for East Poplar 

 River at International Boundary for period 1981-90. 



3.5 

 3.0 



2.5 



J 



u 



O 1.0 

 0.5 



0.0 



Sen Slope Estimate (0.0285 mg/L/year) 



1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 



Year 



Figure 21. — Sen Slope estimate for boron at East 



Poplar River at International Boundary. 



