Township of Nipigon Rain Garden

Situated in the Township of Nipigon, ON, this case study outlines a project to improve management of storm water with low impact development (LID) strategies that use and mimic natural infrastructure and natural processes, specifically a rain garden. This project was undertaken by the municipality as part of ICLEI Canada’s Collaborative Implementation Group project in 2018. Nipigon is vulnerable to heavy rain, hail and windstorms, extreme cold temperatures, and severe heat waves as a result of climate change. The storm sewer works of the project includes improvements to 350 meters of storm sewer collection system and 13 manholes. The intended outcome of this project is to decrease stress on stormwater infrastructure and demonstrate the effectiveness of LID in stormwater management.

Understanding and Assessing Impacts

This case study addresses the climate impacts risks and vulnerabilities related to stormwater management in the Township of Nipigon due to increased heavy rain and melting events, which are anticipated to intensify with climate change. Recent events such as the heavy rain of 2012, the hail and wind storms of 2013, the extreme cold temperatures of 2013, 2014 and 2015, and the severe heat waves of 2015 have highlighted the need to be prepared for and adapt to climate change. In 2015, the Township of Nipigon completed a stormwater master plan that identified opportunities for the improved management of stormwater. The township is particularly interested in exploring the use of LID strategies that rely on natural infrastructure (e.g., soils and plants) and natural processes (e.g., transpiration, filtration) to both reduce peak runoff during rain and melting events, and to improve stormwater discharge quality, particularly by reducing suspended solids. Doing so will reduce the negative impacts of stormwater discharge at its outfall. A primary intention of this project was to explore and demonstrate the utility of LID in the management of stormwater.

Identifying Actions

The development of the stormwater master plan gave direction to developing actions to improve stormwater management in the Township, as well as previous extreme weather events which highlighted the importance of planning and mitigating against the impacts of climate change. Overarching objectives of the rain garden are to: capture stormwater that is currently eroding and deteriorating road shoulders and road base; enhance the removal of suspended solids; reduce the peak runoff/discharge; and reduce the negative impacts of stormwater discharge at its outfall. The outfall is located in an area of a steep bank and discharges to a sensitive receptor. The project had been informally discussed internally with all staff beginning in December 2016, as well as at a Public Works Committee meeting with Mayor & Council. The first few months of project planning were focused on identifying and applying to funding opportunities, beginning the design of the rain garden, and identifying challenges (e.g., procurement of ideal tree species). Once funding was secured through the Clean Water and Wastewater Fund (CWWF), the project team continued to improve the design (e.g., by decreasing its scope to ensure it was within budget) and released a request for quotation, which by September 2017 had been awarded to a local contractor. However, winter conditions forced a delay in the construction of the rain garden until April 2018. Despite this delay, some procurement of project materials has been achieved.


The implementation of the project is set to commence in April 2018, with construction set to be completed by June 2018 (construction was set to commence prior to April 2018, but winter conditions forced a delay in the construction). Despite this delay, some procurement of project materials has been achieved. As of 2020 the project has been fully implemented. However, early in construction it was determined the tree box filters would not be practical. As a result of this, the initial settling basin was made larger (surface area and depth) and the rain garden was lengthened.

Outcomes and Monitoring Progress

2020 was the first full season of service of the project, which provides several benefits to the Township and the community. In addition to environmental benefits and the reduced stress on stormwater infrastructure, the rain garden will help demonstrate the effectiveness of low impact development in stormwater management. This study suggests two primary indicators in order to measure the success of the rain garden. The first involves the measurement of total suspended solids from stormwater discharge after snow melt and significant rainfall events using loading values from the Township’s stormwater management plan. The second indicator involves using the same sampling methods as above to measure total phosphorous. As of 2020, initial observations indicate that the settling basin was observed to remove sediment such as road salt and there was no noticeable discharge from the rain garden itself. Nipigon is also looking into installing a data logger. The data logger would assist with monitoring the drawdown and working towards the “48 hour” Standard Operating Procedure. The project timeline was affected by a delay in the announcement of CWWF funding. Another challenge arose when a second funding application (i.e., Guardian Fund) was declined. Given that the team could not release the RFQ until the funding had been secured, this started a cascade that eventually ended with project construction being delayed until April 2018. During the design phase, a second storm sewer pipe was discovered downstream of the proposed rain garden, which connects to the same outfall as the storm sewer that will be collecting the effluent from the rain garden. These challenges were compounded by an early onset of winter conditions, thus postponing planting and construction work.

Next Steps

A set of recommendations has been established by the Township for long term inspection and maintenance. These recommendations include:

  • Sweep streets at least once after spring melt and again in the fall.
  • Inspect the pre-treatment sump and catch basins downstream of the rain garden outlet for sediment accumulation.
  • Remove any sediment or debris from the pre-treatment sump with a shovel.
  • Remove sediment from downstream CBS when it is found half full.
  • Monitor for sediment accumulation in the rain garden and remove if found in order to maintain the filtration capability of the rain garden.
  • Monitor the rain garden after rainfall events to ensure standing water is gone within 48 hours after events.
  • On a monthly basis, pull or cut weeds and invasive plants in the rain garden.
  • Add mulch to rain garden where it has been depleted.
  • On a monthly basis, add additional plants where necessary (per warranty).
  • Annually cut and remove herbaceous vegetation from the rain garden in early spring and rake downed vegetation.

The implementation of the project began in April 2018, with construction completed by June 2018. The project serves as a demonstration project that can be used to attract funding for other low impact development projects. The project team also hopes that the rain garden will strengthen active transportation in the community by serving as a destination for community members and visitors.


Link to Full Case Study

Using climate change projections enables better adaptation decisions, as it allows you to better understand how the climate may change. To learn how to choose, access, and understand climate data, visit’s Learning Zone.
For more information on variables that may be useful in work related to stormwater and wastewater management, visit and click “Explore by Variable”. Here you will find pertinent future climate projections related to:

  1. Historic and climate change scaled IDF data
  2. Total precipitation
  3. Maximum 1-day total precipitation
  4. Wet days (>1mm, >10mm, >20mm)