34 



3.4.2 Water QuaUty 



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 2000 was 719 mg/L, up slightly from 1999 but still well below past 

 levels. 



3.5 Air Quality 



SaskPower's ambient SO2 monitoring for 2000 recorded one value greater than SERM's one-hour 

 average standard of 0.17 ppm on April 19 and six values greater than the 24-hour average standard of 

 0.06 ppm, four of which occurred on May 12. The ambient SO2 monitor was out of service from June 

 through December. Letters to SERM were sent on June 7 and September 18 informing them of the 

 condition of the ambient SO2 monitor. Readings from the ambient SO2 monitor continue to be 

 infrequent and of insignificant magnitude. The 2000 geometric mean for the high- volume suspended 

 particulate sampler was 19.7 \ig/m^ and 2000 was the ninth consecutive year of below-average 

 particulate readings. 



3.6 Quality Control 



3.6.1 Streamflow 



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

 site on September 19, 2000 by persoimel from the U.S. Geological Survey (USGS) and Environment 

 Canada (EC) to confirm streamflow measurement comparability. Data from the two current-meter 

 discharge measurements are shown in Table 3.5. The measured discharges compared fairly well with the 

 theoretical discharge computation of 0.074 m^/s for the 90° V-notch weir. 



