Environmental Trends 2007

Fresh Water

Water Quality Index for Surface Water Bodies in British Columbia [2002-2004]

The Water Quality Index (WQI) is a tool that allows a large number of water quality characteristics to be expressed as a simple rating for each body of fresh water.

Percentage of water bodies in B.C. with each WQI rating.

Excellent: 3 per cent
Good: 48 per cent
Fair: 39 per cent
Marginal: 10 per cent
Poor: 0 per cent

Source: B.C. Ministry of Environment

• The WQI was calculated for 31 streams, rivers and lakes with sufficient monitoring records between 2002 and 2004. More than half (51 per cent) of the water bodies were rated ‘excellent’ or ‘good’, 39 per cent were rated ‘fair’, 10 per cent were ‘marginal’ and none were ‘poor.’

• As most water quality monitoring stations are intentionally located where there is a risk of water pollution, it is likely that a greater proportion of the thousands of other water bodies in B.C. are actually in good to excellent condition.

For detailed information, including graph data, see In-Depth Report [pdf].