WC148 MayJune 2026 - Magazine - Page 24
STORMWATER
Rethinking Stormwater Management
How Canadian municipalities can adapt to a changing climate
BY DAVID WEEKS
C
ANADA IS SEEING MEASURABLE
INCREASES in the frequency and intensity of storm events, which is outpacing
the historical design assumptions built
into much of the existing municipal
stormwater infrastructure. This is causing an
increase in flooding, hazards to life and property
and allowing pollutants to flow into streams, rivers and lakes.
The increased intensity of today’s storms are
producing higher volumes of stormwater, and
Canadian municipalities need to evolve how they
approach the management of stormwater runoff.
A more strategic approach is needed to ensure the
infrastructure can meet the challenges presented
by a changing climate, while also treating stormwater as a valuable asset.
The following are five best practices that will
help municipalities adopt a more evolved, strategic approach to stormwater management.
1. Update design standards
When it comes to stormwater management, most
of the current design standards and models are
based on outdated precipitation data. They also
do not account for any of the new technology or
alternative materials that have come out in the
last two decades. Much of the municipal storm
sewers, culverts and drainage systems being put
in the ground today were dimensioned using historical rainfall statistics and design storms derived
from a climate that existed years ago.
David Weeks is the
General Manager, Canada Division at
Advanced Drainage Systems.
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WATER C AN ADA • M AY/JUNE 2026
Using historical rainfall records is quickly
becoming an inadequate approach to stormwater
management. Rainfall design storms should account
for future conditions and the change in weather
patterns, rather than historical averages. The intensity
and frequency of today’s larger storm events is
creating a higher volume of stormwater, which is
putting a strain on natural waterways and municipal
infrastructure. For instance, many of the ponds that
have been standardized for over 20 years aren’t big
enough to handle the increased rainfall and storm
intensity and either need to be replaced or reworked.
2. Treat stormwater as a valuable resource
As communities experience higher volumes of
stormwater and/or water scarcity issues, there is
a growing need to view stormwater as a valuable
asset that can be harvested and reused. There is
also a growing focus on removing trash, debris and
pollutants to ensure the water is returned to the
environment in as good—if not better—condition
than when it fell. Federal, provincial and local
conservation authority regulations (e.g., Fisheries
Act, provincial environmental regulations) require
municipalities to limit the discharge of sediment,
nutrients and contaminants into receiving waters.
These regulations often require increased pointsource treatment within each development project
to achieve the overall required quality control of the
stormwater.
There are advanced drainage structures and water
quality products, such as biofilters and sedimentation basins, that help remove contaminants like oils,
heavy metals, microplastics and sediments. They help
ensure the water is ready for re-use or returned to its
natural environment in the same or better condition
as when first captured.
WAT E R C A N A D A . N E T
