The Poplar River Power Station is dependent on water from Cookson Reservoir for cooling. Power 

 plant operation is not adversely affected until reservoir levels drop below 749.0 metres, ^^he dead 

 storage level for cooling water used in the generation process is 745.0 metres. The 2005 recorded 

 levels and associated operating levels are shown in Figure 3.19. 



2005 Cookson Reservoir 

 Daily Mean Water Levels 



Full Supply Level 



-Ten Year Median Level 



2005 



Minimum Desired Operating Level 



Minimum Useable Storage Level 



Feb Mar Apr May 



Jul Aug Sep Oct Nov Dec 



19100 *£ 



c « 

 o E 



8i 



Figure 3.19 Cookson Reservoir Daily Mean Water Levels for 2005 and 

 Median Daily Water Levels, 1995-2004 



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 2005 was 1,033 mg/L, up slightly from the 2004 average level of 

 967 mg/L but still below past levels. 



32 



