Compliance of the East Poplar River water quality with the proposed 

 short-terra objectives for boron and total dissolved solids (TDS) is 

 tested by calculating the 3-inonth (90-day) moving flow-weighted con- 

 centration for each and advancing 1 month at a time while dropping 

 the first month of the 3-month period. Prior to 1982, determination 

 of compliance was based strictly on instantaneous samples. Since 

 the beginning of 1982, daily TDS and boron concentrations have been 

 computed from a regression relationship with specific conductance. 

 However, the data from both instantaneous samples and from calcula- 

 tion of TDS and boron have been presented. 



The Bilateral Monitoring Committee has adopted the approach that for 

 the purpose of determining compliance with the proposed IJC long-term 

 objectives, the boron and TDS data are best presented as a 5-year, 

 flow-weighted moving average which is advanced 1 month at a time. 



East Poplar River at the International Boundary 



Total Dissolved Solids 



The proposed short-term objective for TDS is 1 500 milligrams per 

 litre (mg/L). A plot of the 3-raonth moving flow-weighted concentra- 

 tions is shown in Figure 2. No exceedances occurred in 1984 at the 

 International Boundary. The maximum 3-month, flow-weighted concen- 

 tration during the irrigation season was 869 mg/L. The calculated 

 minimum observed was 734 mg/L. The observed relationship between 

 TDS and specific conductance is: 



TDS = (0.654 X specific conductance - 6.86) (R^ = 0.902) 



The long-term, 5-year moving flow-weighted concentrations for TDS are 

 shown in Figure 2. The long-term, flow-weighted values, as well as 



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