EN5(1) Total Water Use (Including Discharges)

Calendar Year	2001	2002	2003	2004	2005
Sulphate (tonnes)	341	4	9.5	16.9	1.7
Sanitary effluent ('000's m 3 )	124	104	109	97.5	97.5

Marine-sourced cooling water used at the Burrard Generating Station is chlorinated to reduce biofouling in the cooling system when mussel larva are likely to present, typically from late May through mid-December. Before the chlorinated water is discharged, it is treated with sulphur dioxide at the rate of 20 to 50 micrograms per litre to remove the residual chlorine that can be harmful to aquatic life. The treated discharge contains primarily sulphate and chloride as the products of the dechlorination reaction. Because the sulphate concentration in Burrard Inlet is approximately three per cent by weight, this discharge does not change the local concentration detectably.

The total volume of sanitary effluent is estimated from all BC Hydro buildings and offices, excluding generating stations and Surrey Oil Operations, to be approximately equal to that of last year.