increasing trend was noted. Further, similar flow and concentration patterns were observed during this 

 time period in the mainstem Poplar River, which is not as impacted by human influences and was used 

 as a reference stream. Given that TDS concentrations have remained below the short-term objectives of 

 the monitoring arrangement, no increasing concentration trends have been identified, and a surrogate 

 water-quality measurement (specific conductance) can be used to estimate TDS, the Committee 

 recommended that the current monthly water-quality sampling for TDS be reduced to four samples per 

 year. 



TDS water-quality sample data collected by Environment Canada and the USGS in 2003 are shown in 

 Figure 3.4. The TDS concentrations ranged from 690 mg/L on March 25 to 1,054 mg/L on November 

 12. The proposed short-term objective for TDS is 1,500 mg/L. Monthly TDS water-quality sample data 

 were missing and estimated for February, April, October, and December 2003. 



The three-month moving FWC for TDS for the period of record is presented in Figure 3.5. The TDS 

 objecfives have not been exceeded during the period of record. On inspection of the plot in Figure 3.5, it 

 is apparent that the three-month moving FWC increased gradually, year by year, up until the spring 

 runoff of 1997, when an excepfionally heavy snowmeh contributed sufficient water of low ionic strength 

 to the river and the reservoir to dilute the accumulated salts built up in the system. Dissolved-solids 

 concentrations were lower in 2003 relative to those recorded in 2002; however, low spring runoff and 

 higher contribution fi-om ground water have kept the TDS level close to the long-term objective of 1,000 

 mg/L. 



11 



