How We Manage Stormwater

What's in the System

We manage over 600 kms of stormwater infrastructure in Nanaimo (lined up, end to end, it would reach from Victoria to Port Hardy!). This infrastructure includes both built systems and natural features that work together to collect and move rainwater through the city, such as:

• Catch basins: collect and move stormwater underground
• Storm sewers, ditches and culverts: convey stormwater to outfalls
• Outfalls: release water innto natural waterbodies
• Manmade stormwater ponds: hold and sometimes infiltrate and treat runoff
• Natural Wetlands/marshes: absorb and detain rainwater naturally
• Rivers and creeks: guide rainwater to the ocean

How We Maintain the System

Our stormwater system helps protect us from flooding, erosion and pollution, but it needs regular planning and maintenance. Learn how we plan for the system in How Stormwater Management Is Funded and Planned.

Activities we do annually to keep the system working include inspecting, cleaning and repairing:

• At least 613 km of pipes within the storm system (including catch basin leads, culverts and mains)
• 13,583 catch basins
• 23 detention/retention ponds
• 7,262 manholes (MH) as needed
• Approximately 167 km of ditches
• Culverts as needed
• Offer 24/7 emergency coverage

Other activities that help protect our system include brush and weed clearing from ponds and ditches, cutting tree roots out of stormwater mains, and sampling the quality of stormwater entering creeks.

Public Works Programs

Our Public Works team runs several programs that help protect Nanaimo's environment and improve stormwater infrastructure:

Creek Restoration: Creek restoration brings damaged waterways back to a healthier, more resilient state. Recent projects include Departure Creek and Cottle Creek, which have seen more fish as a result of the work completed.

Erosion Reviews: Erosion occurs when water and other natural forces move soil, rock and surface materials from one place to another. Our teams inspect waterways and surrounding land to identify where erosion is happening and why, so we can prevent further damage. 

Rain Gauge Monitoring: Rain gauges help us track rainfall patterns across Nanaimo. This data supports flood prevention and climate adaptation by showing how often and how much it rains in different areas. Monitoring rainfall trends helps us plan for future storms and changing weather conditions.