One of the problems that the 2006 Growth Plan for the Greater Golden Horseshoe was intended to address was the fact that new infrastructure was being built to service low-density areas, while existing infrastructure, especially in some older communities, remained underutilized. Ten years later, the 2017 Growth Plan states:
Increased demand for major infrastructure investments driven by population growth, the need to renew aging infrastructure and continuing infrastructure deficits associated with low-density urban sprawl, combined with relatively scarce financial resources, means an ever greater imperative to plan to optimize existing assets and make the best use of limited resources by considering full life cycle costs.
Despite this concern for optimizing existing infrastructure and minimizing the need to build costly new infrastructure, population allocations to 2031 in the 2006 Growth Plan were made largely without a detailed study of local servicing capacity and constraints in the region.
The consultants who prepared the forecasts for the 2006 Growth Plan considered demographic, social, and economic factors, but incorporated very little in the way of environmental or infrastructure constraints on growth. Most subwatershed-level stress assessments for groundwater quality and quantity in Source Protection Areas were done after population allocations were in place.
A further problem emerged during the implementation of the 2006 Growth Plan. As a Neptis brief pointed out, a policy loophole in the Growth Plan and its supporting documents allowed for leapfrog development in small towns and villages, known in the language of the Growth Plan as "undelineated built-up areas" (UBUAs). Certain municipalities were counting these developments as intensification. The Neptis brief noted:
If municipalities are allowed to count new subdivisions in unbuilt areas of rural settlements as intensification, this will contribute to pressure to bring in piped services from distant treatment plants at considerable cost, even though a relatively small amount of population and employment growth has been allocated to UBUAs. This, in turn, will create pressure to add more development along or near the path of these pipes.
The loophole allowing greenfield development within undelineated built-up areas to be counted as intensification was closed with the release of the 2017 Growth Plan. In future, only development within the delineated built boundary or the delineated built-up area is allowed to be counted as intensification.
A further issue is climate change and its potential effects on the water supply. Although Ontarians (and Canadians in general) tend to take the availability of abundant supplies of fresh water for granted and are among the highest per-capita users of water in the world, there are grounds for concern, as the Environmental Commissioner of Ontario noted in 2017:
Water demand, land use development, and climate change are having significant impacts on Ontario's fresh water resources. Hotter, drier summers reduce the supply of water available to humans and to natural ecosystems precisely when municipal water demand peaks. Drought affected many Ontarians in 2016. Ontarians, especially those whose water does not come from the Great Lakes, can no longer assume they will always have as much water as they want whenever they want it [emphasis added].
This project is intended to show how information on the capacity of and constraints on servicing infrastructure and inland water systems can be used to develop data products and tools that can:
- Create a regional picture of the current capacity of municipal water and wastewater treatment plants that draw water from or discharge wastewater into inland rivers and lakes or use groundwater (aquifers) as a source of water.
- Connect infrastructure capacity data to growth allocations for settlements, using municipal land budget data to evaluate those allocations and ensure growth is directed to areas with adequate infrastructure capacity.
- Connect groundwater (aquifer) capacity data, as well as data on the assimilative capacity of inland waterways and the effects of large subsurface wastewater disposal systems on groundwater sources, to growth allocations in municipalities across the GGH.
- Use information from asset management studies, water and wastewater master plans, and capital project budgets to estimate the cost of building and maintaining infrastructure in terms of life-cycle costs.
Using the information and data products suggested, the Province and municipalities can better evaluate growth allocations and land supplies in the region in the context of the environmental and financial costs of servicing growth.
 Growth Plan for the Greater Golden Horseshoe, 2017, Section 1.1, page 2.
 See, for example, Hemson Consulting Ltd., Greater Golden Horseshoe Growth Forecasts to 2041: Technical Report, 2012.
 Should rural settlements in the Greater Golden Horseshoe be a focus for growth? Neptis Brief, March 2017. https://www.neptis.org/publications/should-rural-settlements-greater-golden-horseshoe-be-focus-growth
 ECO, Every Drop Counts: Reducing the Energy and Climate Footprint of Ontario's Water Use, Annual Energy Conservation Progress Report, 2016/2017, vol. 1, page 7.
 This process will benefit from the fact that the Province intends to introduce a standardized form of land budgeting method to be used throughout the Greater Golden Horseshoe.
 These are communal septic systems with "a design capacity in excess of 10,000 litres per day" (2017 Growth Plan, section 7, page 76). See also Government of Ontario, Large Subsurface Sewage Disposal Systems; retrieved from https://www.ontario.ca/document/design-guidelines-sewage-works/large-subsurface-sewage-disposal-systems