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 SURFACE WATER QUALITY 

 East Poplar River 

 The 1981 report by the IJC to Governments recommended: 



For the March to October period, the maximum 

 flow-weighted concentrations should not exceed 

 3.5 mg/L for boron and 1500 mg/L for total 

 dissolved solids for any three consecutive months 

 in the East Poplar River at the International 

 Boundary . 



For the March to October period, the long-term 

 average of flow-weighted concentrations should be 

 2.5 rag/L or less for boron, and 1000 mg/L or less 

 for total dissolved solids in the East Poplar 

 River at the International Boundary. 



For the period prior to 1982, three-month moving flow-weighted 

 concentrations for boron and total dissolved solids (TDS) have been 

 calculated solely from monthly monitoring results. Since the 

 beginning of 1982, the USGS has monitored specific conductance 

 daily in the East Poplar River at the International Boundary, 

 allowing estimates of daily boron and TDS concentration to be 

 derived from regression relationships with specific conductance. 

 Thus, three-month flow-weighted concentrations for the period 1982 

 to 1987 have been calculated from both the results of monthly 

 monitoring and the daily concentration estimates. 



The Bilateral Monitoring Committee has adopted the approach that 

 for the purposes of comparison with the proposed IJC long-term 

 objectives, the boron and TDS data are best graphically plotted as 

 five-year flow-weighted moving averages which are advanced one 

 month at a time. Each point represents the flow-weighted 

 concentration for the previous five-year period. The methods used 



