3.4.2 Water Quality 



The period from 1987 to 1993 saw very low volumes of surface-water runoff to Cookson Reservoir. 

 Consequently, total dissolved solids (TDS) in the reservoir increased steadily from approximately 780 

 mg/L to over 1,800 mg/L. Since 1993, higher runoff volumes have improved reservoir water quality. 

 Since 1997, the TDS levels in the reservoir have generally remained below 1,000 mg/L. The average 

 TDS level in Cookson Reservoir in 2003 was 928 mg/L, up slightly from the 2002 average level of 910 

 mg/L but still below past levels. 



3.5 Air Quality 



SaskPower's ambient SO2 monitoring for 2003 recorded no values greater than Saskatchewan 

 Environment's one-hour average standard of 0.17 ppm and the 24-hour average standard of 0.06 ppm. 

 The ambient SO2 monitor was replaced in January 2001 which has greatly improved the availability of 

 this information. The 2003 geometric mean for the high- volume suspended-particulate sampler was 17.6 

 |ag/m^ and 2003 was the twelfth consecutive year of below-average particulate readings. One total 

 suspended-particulate concentration exceeded the Saskatchewan provincial standard of 120 ^g/m^/24 

 hours in 2003. This occurred when a reading of 187.4 ng/m^/24 hours was taken on October 24, 2003. 



3.6 Quality Control 



3.6.1 Streamflow 



Current-meter discharge measurements were made at the East Poplar River at International Boundary 

 site on August 6, 2003 by personnel from the U.S. Geological Survey (USGS) and Environment Canada 

 (EC) to confirm sfreamflow measurement comparability. Data from the two current-meter discharge 

 measurements are shown in Table 3.6. The measured discharges compared well with each other and the 

 theoretical discharge computation of 0.053 m^/s for a 90° V-notch weir. 



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