Rain Garden Project

A rain garden is a landscaping feature that helps manage rainwater run-off. During a storm, rainwater is slowed, captured, and slowly filtered into the soils of a rain garden. Rain gardens mimic the hydrological cycle. In this cycle, water is cleansed of pollutants as it percolates into the ground to replenish the water table.  

Rain gardens are important green infrastructure solutions. Green infrastructure refers to a network of natural and constructed features designed to:

• Manage stormwater
• Reduce urban heat
• Improve air quality  
• Provide ecological and social benefits within urban areas.  

Green infrastructure uses natural processes to address environmental challenges and promote sustainability. 

How Rain Gardens Work

A rain garden is a shallow depression in the ground. It is filled with native plants, shrubs and trees and is positioned to capture rainwater and allow it to slowly infiltrate the soil. Each element of a rain garden plays a role in capturing rainwater:  

• Native plants are adapted to local conditions and are easy to maintain once established. Plus, they attract birds, butterflies and other pollinators.
• Gutters and down spouts assist with directing rainwater from a roof to a rain garden. 
• Plants with a deep root system encourage infiltration and help absorb nutrients. 
• A berm holds water in the garden during heavy rains.  

Benefits of Rain Gardens

There are several benefits to having a rain garden, including:  

• Stormwater management: Rain gardens reduce the volume and velocity of stormwater run-off, which helps to prevent erosion and flooding. 
• Water quality: As rainwater percolates through the soil and plant roots, pollutants and sediments are naturally filtered out, improving water quality before it reaches groundwater or nearby water bodies. 
• Biodiversity: Rain gardens provide habitat for various wildlife, including birds, butterflies, and beneficial insects, contributing to local biodiversity. 
• Aesthetics: Rain gardens enhance the visual appeal of landscapes with a variety of natural colours and beautiful seasonal blooms! 

The Regional District of Nanaimo's Rain Garden

The RDN is home to a rain garden. It is located at the RDN’s Administration Office.  

The rain garden was upgraded in 2024 to function properly in capturing and filtering stormwater run-off. To complete this upgrade, the RDN contracted a local landscaping firm. The upgrade included:  

• Removing turf and invasive plants
• Installing fresh soils and mulches
• Planting native plants throughout the site  

The goals of this project included:  

• Amending the existing rain garden so that it properly functions to slow, capture, and infiltrate rainwater run-off 
• Creating a rain garden demonstration site to bring public awareness to rain gardens and other green infrastructure 
• Learning more about green infrastructure installations of this type to inform the Demonstration Site & Interpretive Signage funding program 

Track the Progress of the RDN's Rain Garden Project:

Before Upgrades

The RDN's Rain Garden currently did not function as a rain garden should. The 22-meter-long swale runs along Hammond Bay Road on RDN property. The depression of the rain garden was covered in turf grass, which covers hard-packed and nutrient-poor soils. Some invasive species, including English Ivy, surrounded the site. This reduced the opportunity for water retention and infiltration within the rain garden. Instead, rainwater run-off captured by the rain garden pooled in the depression before entering stormwater drainage on site.

 

 

Planning

The RDN planned to upgrade the rain garden so that it functions properly and serves as a public demonstration site by: 

• removing turf grass and invasive species
• amending the soil and installing mulch
• planting native plant species throughout
• installing pathways and interpretive signage for public awareness and engagement

 

Installation

Upgrades happened in May 2024. Through early May, excavation of the turf and invasive species, shaping and sloping, and rock installation was completed. This was followed by the installation of fresh soils and organics. The landscaping professionals took care to salvage and re-purposing as many plants as possible while protecting the established trees on site. Later, native plant species were planted throughout the rain garden. 

 

 

Completion 

 

Our Raingarden in Action

 

Contact waterstewardship [at] rdn.bc.ca with any questions.