Uncertainty in sustainable water quality management

• Main Author: McLean, Bruce
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/5883

The decision to upgrade the Annacis and Lulu Island sewage treatment plants in the Greater Vancouver Regional District (GVRD) was analysed in light of uncertainty regarding future population growth and inputs from industrial and urban runoff sources. Sustainability is often cited as a reason for maintaining pristine water quality. However, there are several sustainability world views and they do not all necessarily advocate the maintenance of pristine water quality. Approaches to sustainability are reviewed and discussed in the context of water quality management. Methodology was developed to link discharges from industrial sources, urban runoff and sewage treatment plants to user defined inputs of economic activity, development and land-use patterns and population growth. The pollutant loading was then used to determine the water quality at various locations in the Fraser River Estuary. Inputs from industrial sources, urban runoff and sewage treatment plants upstream of the GVRD were assumed to be completely mixed at the sewage treatment plant outfalls and to affect ambient water quality. Local impacts from urban runoff, industrial discharges and upstream sewage treatment plants were not considered. The primary reason for considering these sources was to determine whether future levels of discharge are likely to have an effect on management decisions regarding municipal sewage treatment plants. Diffusion factors and dispersion coefficients have been determined for various locations in the Fraser River. These were adapted to determine the local impacts on water quality from future increases in sewage treatment plant discharge. The changes in ambient and local water quality were added to determine the overall water quality for each future scenario. The decision to upgrade the two treatment plants was discussed in the context of water quality criteria and sustainability world views.