Low impact development stormwater management guidance manual

Description of policy

The Ontario Ministry of the Environment and Climate Change (ministry) is seeking public input on two consultants’ reports; a jurisdictional scan of international stormwater management requirements for controlling rainwater volumes, and potential runoff targets.

The ultimate goal of stormwater management is to maintain the health of streams, lakes and aquatic life. To achieve this goal, stormwater management strives to maintain the natural hydrologic cycle, prevent an increased risk of flooding, prevent undesirable stream erosion, and protect water quality.

The ministry is proposing to work with all partners in a stepwise, science-based process to update its LID guidance. Following public comments on these two reports, a draft LID guidance manual will be developed and posted for public comment on the Environmental Registry. Finally, these public comments would be used to finalize the LID guidance.

LID uses design techniques that mimic the natural environment by infiltrating, filtering, storing and holding back water runoff close to its source. Examples of LID design include bioretention facilities, rain gardens, vegetated rooftops, rain barrels, and permeable pavements.

Improving stormwater management practices in Ontario will ultimately contribute to the preventative and protection goals set out in the:

• Great Lakes Strategy and the Great Lakes Protection Act
• Climate Change: Development of guidance for LID supports ongoing implementation of Climate Ready: Ontario’s Adaptation Strategy and Action Plan, including the commitment to develop better guidance for stormwater management in the face of a changing climate. Application of LID techniques will increase the resilience of urban infrastructure by limiting the impact of extreme precipitation events, which are projected to happen more frequently as a result of a changing climate.
• Domestic Action Plan for Lake Erie: The amount of phosphorus washed off surfaces (e.g., from properties, streets) and transported into Lake Erie is variable and is dependent in large part on runoff from the land, and therefore is heavily influenced by precipitation. LID stormwater management will reduce the volume of runoff and thereby reduce phosphorus loads to lakes and streams. Overall, LID helps to maintain and restore the natural water cycle.
• The Lake Simcoe Protection Plan: The LSPP requires municipalities to improve stormwater management practices. LID solutions are acknowledged as the foundation for stormwater management within the Lake Simcoe watershed, as experts suggest that LID techniques offer an effective and affordable alternative to mitigate the environmental impacts of urbanization, while offering beneficial outcomes to developers, municipalities and the public.

Purpose of policy

This is the first step in the process of working with all partners to develop a LID Guidance Manual. The purpose of the LID Guidance Manual, once finalized, is to clarify the ministry’s expectations with regard to LID stormwater management, and related runoff volume and water quality control expectations. The Manual is intended to be used by municipalities, conservation authorities, land developers and their consultants. Similar to the 2003 Stormwater Management Planning and Design Manual, this Guidance Manual will provide the framework for ministry staff involved in assessing and approving stormwater management proposals.

The finalized Guidance Manual would help provide transparency and consistency for the ministry’s expectations for stormwater management proposals employing LID techniques.

The ministry anticipates that the new LID Guidance, once fully developed and finalized based on public input, and in conjunction with ministry’s existing Stormwater Management Planning and Design Manual (2003), would be used by municipalities, developers, and others to help plan, design, or implement stormwater management.

Other information

As part of the manual development process, two documents have been developed by consultants: Jurisdictional Scan of Canadian, US and International Stormwater Management Volume Control Criteria Draft Final Report and, Runoff Volume Control Targets for Ontario Final Report. These documents reflect the consultant team’s expertise, knowledge and experiences as well as input from select key stakeholders. The information in these documents, and the public comments on these documents, will help inform the content of the Ministry’s draft Low Impact Development Stormwater Guidance Manual. These documents are attached for public review.

The purpose of the Jurisdictional Scan is to identify the runoff volume controls that have been implemented as part of national, provincial or state, or regional criteria or standards. The scan includes a rationale proposing the selection of jurisdictions recommended for further review.

The Runoff Volume Targets Report further examines stormwater runoff volume targets employed in select jurisdictions, for new development, redevelopment, infill, and retrofit, taking into consideration such factors as combined sewer areas, flood prone areas, and the receiver. This report also proposes runoff volume targets that may be appropriate for Ontario for new development, redevelopment, retrofit and infill, along with a supporting rationale. This Runoff Volume Control Targets Report also includes definitions necessary to ensure understanding of the implementation of the volume targets.

This posting is an opportunity to comment on the stormwater management in Ontario. Implementation of LID techniques could result in more stormwater management facilities distributed in the urban area and, potentially, fewer/smaller end of pipe facilities like extended detention wet ponds. The following questions are examples of the issues that may be addressed:

• Are the conditions in the other jurisdictions that were investigated similar to the conditions in Ontario?
• Are the approaches to runoff volume control used in other jurisdictions appropriate?
• Does Ontario have unique or localized factors that would affect the implementation of runoff volume controls?
• Are there any issues with the rationale used to propose runoff volume control targets for Ontario?
• Are the proposed levels of runoff retention appropriate for protection of the environment of Ontario?
• Are the different development scenarios adequately defined and are the requirements for the different development scenarios sufficient?

The feedback from this consultation will be considered in development of proposed LID Guidance which, will also be posted for public consultation.

Public consultation

This proposal was posted for a 30 day public review and comment period starting June 15, 2017. Comments were to be received by July 15, 2017.

All comments received during the comment period are being considered as part of the decision-making process by the Ministry.

Please Note: All comments and submissions received have become part of the public record.

Other public consultation opportunities

Once developed, the draft Low Impact Development Stormwater Management Guidance Manual will also be posted for comments on the guidance and on the implementation.