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Stormwater in Nanaimo: Why it Matters

Every time it rains, your property, your street and our environment are affected. Learn why stormwater matters and what you can do to help.

What is Stormwater?

Stormwater is the rain or melted snow that flows off hard surfaces like rooftops, parking lots and driveways. In natural areas, this water would soak into the ground. But in developed areas, it runs into drains and ditches picking up oil, litter and chemicals, which can carry them into our rivers and lakes and out to the ocean.

Visual representation of how precipitation impacts groundwater recharge and surface runoff in rural and urban environments.

Challenges with Stormwater

You might not think about stormwater until you see a flooded street, a backed-up drain or a murky stream but unmanaged stormwater runoff can:

  • flood homes and roads,
  • erode streambanks,
  • pollute waterways, and
  • damage infrastructure.

A suburban street is flooded with water reaching up to garages and yards, surrounded by leafless trees and wet grass.
Buttertubs Dr Flooding in January 2018
The Millstone River turned red from a chemical spill.
Millstone River turned red from a spill

Your Role in the Stormwater Story

Every property in Nanaimo is part of a catchment area - a zone where rainwater flows into shared drainage systems and then out into the natural environment. The map below shows that we all contribute to stormwater runoff. It's a reminder that wherever somethings goes down the drain or into a ditch, it will end up in the natural environment.

Color-coded map showing prioritized storm drainage catchments across a large region with distinct boundaries and labels.

View pdf

Learn More

To learn more about stormwater and its system in Nanaimo, check out the links below.

Last updated: September 15, 2026

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