Natural infrastructure for a climate-ready Ontario

Natural services of wetlands are cost-effective complement to built infrastructure

We commissioned research to look at how wetlands are currently integrated into flood management in southern Ontario communities, and asked what is needed to remove barriers that prevent deeper integration of wetland conservation into flood management.

We found that the natural flood-management services of wetlands are a cost-effective complement to traditional infrastructure built to protect communities from floods, providing evidence for wetland conservation as a best practice for climate readiness. We also found a growing understanding of the benefits of wetlands—for example, among public sector and water-management experts—but increased awareness has yet to be fully translated into action.

Communities need tools for natural infrastructure planning

DUC’s conservation mission is aligned with a climate-ready Ontario. We have conserved and restored wetlands and adjacent habitats in Ontario for decades. Working with many partners—including thousands of private landowners—we protect and restore wetlands to support the natural infrastructure of landscapes.

This research is another step towards ensuring that communities have the tools they need to fully integrate natural infrastructure into their planning practices for a resilient future.

Wetlands for flood resiliency

Research commissioned by DUC:

• Assessed the extent to which municipalities are opting to combine wetlands with their built infrastructure to reduce the risk of flooding, and to determine their reasons for doing so
• Analyzed how municipalities and other agencies assess the costs and benefits of employing wetlands for flood mitigation

We found that wetlands in combination with traditional infrastructure can be more cost-effective for flood mitigation than using built infrastructure on its own. The cost savings of employing wetlands can be calculated by estimating 1) avoided costs of built infrastructure needed to replace wetland flood-mitigation services or 2) avoided costs of damages if the flooding is controlled.

Theme: Increased awareness of wetland flood reduction value not driving more conservation (yet)

Findings from municipal reports and plans suggest there is a growing understanding of the flood mitigation benefits of wetlands.  But due to a variety of reasons (see barriers following), increased municipal awareness has yet to be fully translated into actions to mitigate flood risk by leveraging wetlands. However, regulatory requirements for asset management plans to include green infrastructure assets by 2023 will be a key driver for Ontario municipalities and their partners to evaluate, manage and invest in wetlands—potentially making wetland protection and restoration standard municipal practice for flood risk reduction and other benefits such as water quality improvement.

Theme: Cost-benefit analyses of employing wetlands for flood mitigation need to mature

Conducting cost-benefit analyses (i.e., building the business case) for employing wetlands for flood mitigation in combination with traditional/grey infrastructure can be challenging for municipalities and, in some cases, not given any consideration. Our literature review found the lack of a standardized approach for wetland CBAs has caused problems by leaving “each study open to critique of what assumptions and limitations are acceptable to decision makers.”  To be most useful, municipal or watershed-scale CBAs should consider the cost/benefit components from the perspectives of different stakeholders such as farmers, developers and other landowners.

Theme: Potential risk to employing wetlands for flood mitigation

Increased use of existing and restored wetlands for flood mitigation/stormwater management comes with a risk of potential indirect impacts on wetland ecosystem services, for example, increased pollution, increased run-off and higher peak flows. This finding from the literature review aligns with responses from several professionals who indicated that wetlands should not be used for stormwater/flood management because ecosystems would be degraded. The research emphasized that a holistic Low Impact Development (LID) approach, including Better Site Design standards, will reduce both indirect and direct wetland impacts from nearby developments.

Theme: Watershed-based approaches and other innovations are keys to success

Watershed-based approaches to stormwater management are becoming more common as downstream solutions prove insufficient to mitigate floods. Our research found that a sub-watershed and watershed-scale approach to flood mitigation is important to leverage successful wetland-based solutions that may be included in Municipal Class Environmental Assessments including Stormwater Master Plans.  Public-sector agencies are studying the benefits of watershed-based approaches in place of municipal-based approaches: for example, Lake Simcoe Region Conservation Authority, Toronto and Region Conservation Authority, and York Region and its partners are working on a “Watershed-scale Model for Stormwater Management and Risk Mitigation” to identify the management actions that provide the greatest cost-benefit for flood control and water quality improvement.

Another innovation being implemented by municipalities, including York Region, is to convert stormwater management ponds to hybrid wetland systems that serve dual functions to attenuate high-flow events and reduce phosphorus loads passing downstream.

Selected barriers to choosing wetlands for flood reduction

 We identified barriers that prevent or impede wetland conservation activities aimed at reducing flood risk and recommendations to overcome them.

• Lack of knowledge regarding the flood mitigation services of wetlands and the business case for employing wetlands for that specific purpose
• Organizational silos and lack of awareness of common objectives across departments
• Need for more advocacy through public planning processes
• Lack of professional or standardized best practices for municipal plans to consider wetland conservation for the purpose of flood mitigation
• Lack of information and professional resources to support wetland conservation/natural asset management
• The minimum level of service (i.e., extent of flood risk mitigation) required of municipal stormwater management infrastructure is not standardized

Priority recommendations for action

Recommendations arising from the research to overcome these barriers include actions that can be led by DUC and others to be led by municipalities. We selected four recommendations as DUC’s first priorities for action:

1 – Evaluate CBA tools currently used to assess the effectiveness of wetland conservation for flood mitigation in terms of their strengths, weaknesses and applicability to specific types of common wetland conservation opportunities.

2 – Facilitate a workshop with multidisciplinary representatives from municipal departments to identify and address barriers or opportunities regarding use of wetland conservation for flood mitigation. Laws, standards, regulations and policies may be unintentionally creating barriers or there may be opportunities for change that would accelerate wetland conservation.

3 – Partner with a municipality to develop a case study demonstrating how wetland conservation can be integrated into municipal processes to achieve flood management and climate resiliency objectives (e.g., Official Plan, Municipal Asset Management Plans).

4 – Develop resources to support municipalities in their decision making around wetland conservation, including recommended standard methods for CBAs and compiled supporting literature.

• Download this information brief as a PDF.

• The full report, Municipal Conservation of Wetlands for Flood Resiliency, prepared for DUC by Emmons and Olivier Resources is available on request. Our thanks are due to the many municipal professionals who took the time to share their knowledge and experience with us.

The research, which advances the science on the use of wetlands as “natural infrastructure” to reduce flood risks for communities in southern Ontario, was commissioned with support from the Ontario Trillium Foundation, which awarded DUC a Seed Grant of $74,800 in 2018.

Ontario Provincial Office

Tel 705-721-4444 or Email du_barrie@ducks.ca