The study shows that linking various Ministry of the Environment and Climate Change (MOECC) databases and other data sets through unique identifiers such as a Drinking Water System Number (DWS#), an Environmental Compliance Approval Certificate (ECA), or even a plant name, is both possible and necessary.
Linking is important. Although municipalities know the capacity of individual plants in their jurisdiction, the regional picture is missing. Creating a regional picture involves linking data on water resources and flow with data on water and wastewater treatment plants. It will also require taking a watershed approach to develop a cumulative picture of the demands and constraints on each inland waterbody, such as the Grand River or Lake Simcoe.
We found, however, that while MOECC's Drinking Water Information System (DWIS) database has information about design capacity, it does not track average daily volume of water and maximum daily water and wastewater flow. If the flow data are not available in a database that can be linked to DWIS, they will have to be linked to two other databases: the Permit To Take Water information system, which tracks what water takings are allowed, and Flow Summary Reports published by municipalities as part of their compliance reporting process.
Figures 4 and 5 illustrate the ways in which the available data could be linked to provide a more complete picture of water and wastewater in the region.
Figure 5: Potential linkages for wastewater data sources
The value of such datasets and databases increases considerably if they can be linked with other data such as:
- Municipal settlement area data sets from official plan mapping by the Neptis Foundation and Ministry of Municipal Affairs to compare environmental and infrastructure capacity with land use patterns. Of interest would be growth allocations by settlement area, which are available in municipal land budgets approved by MMA. These land budgets contain detailed information about the types of housing units and the people per unit (PPU) used by municipalities to allocate population to housing units and land for greenfield development and urban settlement area expansions, where necessary.
- Environmental constraints data, such as aquifer limits and the assimilative capacity of inland lakes and rivers. This component would rely on streamflow, lake water levels, and water quality data from Environment and Climate Change Canada, the Ontario Ministry of Natural Resources and Forestry, the Ontario Ministry of the Environment and Climate Change, and conservation authorities. These data would allow for estimations of assimilative capacity to determine where environmental pressures are greatest. This linking would be part of the decision-support tool in Phase 3 of this study.
- The cost of expanding piped infrastructure and municipal water and wastewater treatment plants to accommodate planned growth to at least 2041 under the Growth Plan for the Greater Golden Horseshoe.
 MMA allocates population to single-tier municipalities and to upper-tier municipalities; the latter in turn distribute these allocations to their lower tiers.