Maunder D.

Zimmer C.

I-Revues

SESSION 9.3 
NOVATECH 2007  1755 
Development and Implementation of an 
Integrated and Sustainable Watershed Strategy 
through the Process of Adaptive Environmental 
Management 
Le développement et l'application d'une stratégie de gestion 
intégrée et durable des bassins versants par un processus de 
gestion environnementale adaptative 
Dave Maunder* and Christine Zimmer** 
* Manager, Water Resources and Environmental Divisions 
Aquafor Beech Limited 
8177 Torbram Road, Brampton, Ontario, Canada, L6T 5C5 
Telephone Number: 905-790-3885 ext. 290 
Email: maunder.d@aquaforbeech.com 
** Senior Water Resource Engineer, Credit Valley Conservation Authority 
RESUME 
La mise à jour d’un plan directeur de gestion des eaux de la Rivière Credit comporte 
une analyse du basin versant en tenant compte des interventions humaines ou 
naturelles (tel l’aménagement des terres ou le changement climatique). L’objectif de 
cette étude était d’évaluer et de sélectionner un plan qui a pour but d’assurer 
l’approvisionnement en eau abondante et saine, soit pour la population humaine ou 
pour la fauve dans le bassin versant de la Rivière Credit. Cette étude a tenu compte 
d’autres initiatives, tel le Oak Ridges Moraine Conservation Plan, Smart Growth et la 
2e phase du rapport O’Connor. La question peut se poser ainsi: “Comment gérer la 
croissance espérée dans un encadrement écosystématique”?  Le plan directeur a été 
réalisé par conciliation avec les multiples usagers – municipaux, provinciaux, 
académiques et individuels. 
ABSTRACT 
The Credit River Water Management Strategy Update used a decision support 
system to analyze the watershed’s response to various stressors (land use and 
climate change scenarios).  The goal was to evaluate and select a preferred 
management strategy that ensured “abundant, safe water” now and in the future for 
people and wildlife in the Credit River watershed.  The study incorporated initiatives 
such as the Oak Ridges Moraine Conservation Plan, Smart Growth, Phase II 
O’Connor Report and other provincial initiatives to address the question “How much 
can we grow, and where/how can we grow from an ecosystem perspective? “  The 
strategy was developed through working partnerships with municipalities, provincial 
agencies, academics and individual groups. 
KEYWORDS 
Adaptive Environmental Management, Impact Assessment, Implementation, 
Sustainable Development, Watershed Strategy. 
 
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1 INTRODUCTION 
The main branch of the Credit River extends from the headwaters north of the Town 
of Orangeville to Lake Ontario at Port Credit (approximately 100km through the 
watershed). The Credit River watershed lies within the most densely populated region 
of Canada and supports a wide range of land uses including urban (23%), 
active/inactive agriculture (30%), forest (14%), pasture lands/old field (16%), wetlands 
(6%), and water bodies (4%). The drainage area of the watershed is approximately 
1,000 km2. 
Despite historic and present land use changes, many parts of the Credit River 
watershed remain in a relatively healthy condition. The beauty of the area is enjoyed 
by thousands of hikers, tourists and sportsmen throughout the year. The southern 
reach of the Credit River is nationally recognized for its impressive fall runs of pacific 
salmon and rainbow trout (steelhead) which are stocked annually. Many parts of the 
northern section fo the watershed support self-sustaining cold water fish populations. 
Anticipated growth within the watershed is considerable. According to the Ministry of 
Public Infrastructure and Renewal (2005) AND Places to Grow (ref 1), the two largest 
Regions are anticipated to grow by 60-100% in the next thirty years.  
In light of these development pressures, it is critical to plan where growth occurs and 
how it will proceed.  In such planning, the careful management of urban stormwater 
will be critical to protect public health.  The objective of the Credit River Water 
Management Strategy (CRWMS) was to develop a decision support mechanism to 
implement upfront planning and sustainable management practices for various 
stressors such as future land use changes and climate change scenarios.  The goal 
was to select a management strategy that ensures “abundant, safe and clean water” 
now and in the future for both the people and wildlife within the Credit River 
watershed. 
2 METHODS 
The Credit River Valley Conservation’s (CVC’s) approach to managing proposed 
development involves a number of steps. CVC together with the 11 member 
municipalities jointly provide input to Official Plans and Infrastructure Renewal Plans. 
Furthermore, a comprehensive monitoring program has been undertaken in order to 
evaluate how the watershed will respond to various stressors such as development, 
climate change, and human activities (water takings, aggregate extraction etc.). 
Comprehensive watershed wide studies are also undertaken periodically in order to 
provide a decision-making framework. The initial watershed study was undertaken in 
the late 80’s through early 90’s. this study was initiated in the fall of 2003 and 
completed in the summer of 2006. 
Through the use of scientific studies the CVC and partner municipalities can then 
identify and implement the best management strategy to protect public and 
environmental health. Long term monitoring can then evaluate the effectiveness of 
management decisions.  Using an iterative approach to watershed management 
allows CVC and its municipalities to use Adaptive Environmental Management (AEM) 
techniques to respond and protect the environment.  The premise of AEM is to define 
clear, measurable goals and develop a model, such as a watershed framework, to 
develop an understanding of watershed functions and relationships. 
The methods/techniques used in this study initially involved the development of an 
integrated set of study goals and objectives which were then linked to a series of 
measurable parameters and targets at 20 representative locations throughout the 
SESSION 9.3 
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watershed. Examples of objectives used to evaluate existing and future scenarios 
included: 
• Minimize risk to human life and property due to flooding 
• Protect groundwater quality to support watershed functions 
• Improve water quality in rivers and Lake Ontario for body contact recreation 
• Protect, restore or enhance the integrity of the watershed ecosystem through an 
integrated network of natural areas, habitat and connecting links 
Integrated surface (Hydrolic Simulation (HSPF)) (ref 2) and groundwater (Finite 
Element Flow (FEFLOW)) (ref 3) models were then used to establish existing 
environmental conditions and to simulate various stressors for different land use 
conditions and Management Alternatives (a Management Alternative si defined as a 
set of Best Management Practices (BMP’s) which, when implemented collectively, will 
attempt to address the impacts associated with urbanizing areas as well as those that 
presently exist). As is illustrated below, the Management Alternatives range from Do 
Nothing, to continuing present practices, to implementing an aggressive and 
comprehensive approach which has not been tried within Canada.  The land use 
scenarios that were modeled included: 
• 2006 – existing conditions (15% urbanization) 
• 2051 – future land use conditions (25% urbanization) 
The Management Alternatives that were applied to the 2051 land use scenario 
included: 
• Do Nothing: Absence of any stormwater BMP’s in urbanizing areas 
• Business as Usual: Continuing with current Best Management Practices 
• Technology and Economic Driven: Overcome current technical and economic 
barriers which limit implementation of Best Management Practices 
• Ecotopia: Greater consideration of the environment in land use planning and 
aggressive stormwater management 
Also included in the technical assessment was the retrofitting of existing land use. 
Examples of retrofitting included disconnecting roof leaders, installing rain barrels, 
tree planting, upgrading municipal infrastructure and wastewater treatment plants, 
etc. 
3 RESULTS AND DISCUSSION 
The study objectives, measurable parameters and targets (4000 in total) were initially 
used as a basis to screen out acceptable Management Alternatives (MAs which 
resulted in conditions equal or better than existing conditions were deemed to be 
acceptable). A subsequent set of social, economic, and environmental criteria were 
then used to select the Preferred Strategy. 
Some of the key findings are summarized below. The findings are also presented 
graphically in the accompanying figures. 
• Existing watershed conditions show some degradation in the environment, (refer 
to Figure 1) 
• Current planning and development practices are not sustainable (refer to Figure 
2). 
• Growth can occur in a sustainable manner if we change current planning and 
development practices and implement aggressive stormwater management per 
the Ecotopia management alternative (refer to Figure 3). 
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• Restoration of existing rural and urban land uses is critical to maintain and 
restore existing environmental conditions within the watershed. 
Ecotopia for new development involves stormwater management controls at the site 
level (i.e. bioretention cells, rain gardens, street swales, green roofs, tree box filters, 
etc.) to mimic predevelopment hydrology-enhancing evapotranspiration, infiltration 
and storage to manage stormwater quantity, temperature and quality. Furthermore, 
the form and layout development recognizes environmental features such as 
wetlands, mature forests, steep slopes, and riparian buffers to maintain 
predevelopment hydrology and minimize the amount of impervious cover by reducing 
road widths, sharing driveways, limiting sidewalks to one side of the road, utilizing 
curbless roads, pervious driveways, and discouraging street layouts such as cul-de-
sacs (which increase impervious area), etc. Ecotopia for existing lands includes 
working with homeowners and businesses to adopt similar approaches as noted 
above. It also involves working with municipal staff to ensure replacement of 
infrastructure reflects the environment principles as laid out in the document. It also 
involves dealing with farmers, special interest groups and agencies to restore 
degraded areas within the watershed. In comparison to existing conditions 
implementation of the Ecotopia Management Alternative (the Preferred Strategy) 
would result in: 
• Improved water quality 
• Reduced flood risks 
• Improved conditions for fishery, wildlife 
• Enhanced groundwater supply 
4 SUMMARY AND CONCLUSION 
One of the key conclusions that was arrived at during the course of the study was that 
current development practices are not sustainable, we therefore need to change the 
way we do things if growth is to continue. Furthermore, we need to restore (retrofit) 
existing rural and urban landuses if we wish to maintain, enhance or restore 
environmental conditions within the Credit River watershed. 
The question then becomes; how do we implement change for new development? 
And, how do we change our approach and find funding alternatives needed to 
restore/retrofit existing rural and urban areas? 
Change, in the context of this study refers to a number of items, including: 
• Changing the mindset of consultants, municipalities, developers and agencies 
with respect to the current approach for undertaking stormwater management; 
• The requirement to develop a progressive approach for integrating stormwater 
management measures into subdivision/site planning design; 
• Revisiting/modifying existing municipal and agency policies and standards; 
• Initiating pilot projects for stormwater management measures (e.g. green roofs, 
roof downspout disconnection, filtration systems, alternative municipal 
infrastructure systems) which have not yet been proven in Ontario; 
• Considering alternative sources of funding for the proposed measures in order to 
ensure that the requirements as outlined are funded in a sustainable manner; 
• Consideration of incentives (credits) for progressive submissions. 
As a result of undertaking this study a number of key recommendations were 
provided. These recommendations provide a framework for developing the 
SESSION 9.3 
NOVATECH 2007  1759 
Implementation Plan. The recommendations, which incorporate key components of 
the study are summarized as follows: 
• Principle - Recognize rainwater, groundwater and snowmelt as valuable 
resources; manage rain where it falls - on lots and streets – before it enters 
sewers and streams. 
• Targets - Formally adopt the Strategy goal, principles, objectives, measurable 
parameters and targets as a basis for future municipal endeavours 
• BMP Measures - Implement a hierarchy of water quality/quantity  BMP’s in all 
new development and redevelopment undertakings as well as existing landuses 
using a full range of potential source, conveyance and end-of-pipe controls and 
restorative measures consistent with the recommended strategy. 
• Policy/Standards - Ensure municipal planning and development policies, 
guidelines, processes and standards incorporate an integrated ecosystem 
approach that draws on the collective expertise and experience of planners, 
engineers and landscape architects. 
• Funding - Initiate the necessary programs/policies to staff and fund a range of 
retrofit and restorative measures within existing urban and rural areas as 
recommended in the Strategy. 
• Administration - Put in place an appropriate administrative structure to guide and 
oversee Strategy implementation and actively contribut to the work of the 
Management Steering Committee (MSC) and Working Groups (WGs). 
With respect to the last point a series of Working Groups involving CVC staff, 
municipalities, developers, consultants, and stakeholders and other specialty groups 
have been formed. These groups are working cooperatively to ensure the 
components as noted above, are implemented successfully. 
LIST OF REFERENCES  
 
Ministry of Infrastructure and Renewal. 2005. Places to Grow: Better Choices, Brighter Future. 
Proposed Growth for the Golden Horseshoe. November 2005. Queens Printer. 
U.S. EPA, 1996. Hydrological Simulation Program – FORTRAN (HSPF) Users Manual for 
Release 11. Athens, Georgia 30613. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Figure 1 – Existing Environmental Conditions within the Credit Valley Watershed 
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Figure 2 – Environmental Conditions within the Watershed applying Business as Usual Practices 
and Retrofitting Existing Land Uses (at 25% Urbanization) 
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Figure 3 – Environmental Conditions within the Watershed applying Ecotopia and Retrofitting 
Existing Land Uses (at 25% Urbanization) 
 


Le développement et l'application d'une stratégie de gestion intégrée et durable des bassins versants par un processus de gestion environnementale adaptative

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Le développement et l'application d'une stratégie de gestion intégrée et durable des bassins versants par un processus de gestion environnementale adaptative

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