Municipalities currently do a high-level annual calculation of the capacity remaining in water and wastewater treatment plants to identify places where growth is putting pressure on existing services. This calculation uses data from the Annual Flow Summaries for each water treatment plant and Annual Performance Reports for wastewater treatment plants.
The currently committed capacity for each facility can be assessed using the following equation:
AVERAGE DAILY FLOW / AVERAGE MAXIMUM FLOW
------------------------------------------------ x 100
TOTAL DESIGN CAPACITY / RATED FLOW CAPACITY
=
% COMMITTED CAPACITY OF THE WATER/WASTEWATER TREATMENT PLANT
The resulting percentage is not the whole story, of course. Some apparent shortfalls in capacity can be addressed by increasing operational efficiencies or decreasing demand through water conservation efforts. Whether these measures are sufficient to allow growth in settlements where treatment systems are close to or at capacity will vary from settlement to settlement.
Nevertheless, a high-level regional picture of infrastructure capacity can be linked to planned settlement areas through municipal land budgets, information on sourcewater quantity and quality, and the assimilative capacity of inland lakes and rivers. The data sources identified can help create this regional picture, but the ease with which it can be created will depend on whether MOECC and other datasets identified in this report are made publicly available.
As noted earlier, it is possible to connect information on the amount and type of wastewater effluent being discharged into a river or a lake, along with the discharge point and the name of the receiving water body, to data on the assimilative capacity of the river or lake. This information must be placed in the context of other land uses, such as agriculture, and other types of runoff, such as stormwater, which add to the assimilative burden on waterways.