Stormwater

Stormwater is rain and snowmelt that flows over roofs, roads, parking lots, and other hard surfaces. As it travels, stormwater can pick up pollutants such as sediment, oil, metals, nutrients, and debris before entering the City’s storm drainage system. Unlike wastewater, stormwater is not treated before it reaches local creeks, rivers, and lakes.

Stormwater can also become groundwater through infiltration, a natural process where rain and snow melt soak into the ground and refill groundwater aquifers.  In areas in Chilliwack such as Sardis-Vedder, it is especially important to protect the groundwater since it is the source of drinking water for many residents. 

Proper stormwater management is essential to protecting water quality, aquatic ecosystems, and community infrastructure.

Why Stormwater Management Matters

Urban development increases hard surfaces that prevent rainwater from soaking into the ground. This can lead to higher runoff volumes, erosion, localized flooding, and increased pollution entering nearby watercourses.

Stormwater management helps to:

• Reduce flooding and erosion
• Protect fish habitat and aquatic life
• Safeguard drinking water sources
• Maintain healthy creeks, rivers, and wetlands and,
• Support climate resilience during intense rainfall events.

Protecting Watercourses and Aquatic Habitat

Many of these streams provide habitat for a variety of wildlife including; birds, mammals, reptiles, amphibians, and fish such as  salmon, and the federally protected Salish Sucker, a species at risk. Aquatic life also depends on clean, cool water, stable flows, and healthy stream habitat to survive. Poor stormwater quality, excess sediment, and altered flow patterns can degrade habitat and place additional stress on vulnerable populations. 

To support consistent protection and management of watercourses, the City of Chilliwack uses a watercourse classification system. Watercourses are categorized based on factors such as fish presence, habitat value, and ecological function. This classification helps guide planning, development review, and maintenance activities near watercourses, ensuring that more sensitive and higher-value streams receive appropriate protection.  

The classification system also supports stormwater management by recognizing how changes in runoff, flow, and water quality can affect different types of watercourses. By considering watercourse classification early in planning and design, the City helps reduce impacts to aquatic habitat and protect the long-term health of local creeks and rivers.

Pollution Prevention

Preventing pollution at the source is one of the most effective management tools since stormwater systems flow directly to groundwater and our local watercourses. 

Residents and businesses can help protect stormwater by: 

• Keeping catch basins clear of leaves and debris
• Never pouring oils, chemicals, or wash water into storm drains 
• Washing vehicles at commercial car washes or on permeable surfaces 
• Drain your swimming pool at a low flow rate into your lawn or into the sanitary sewer 
• Properly storing and disposing of waste and hazardous materials
• Using fertilizers and pesticides sparingly

Everyone Has a Role

Stormwater management is a shared responsibility. Everyday actions on private property, at businesses, and in public spaces influence what enters the storm drainage system and ultimately recharges our groundwater and reaches our local watercourses.

The City’s Storm Drain Marking program and Adopt a Catch Basin program help raise awareness about this connection. Markers placed on catch basins remind residents that storm drains flow directly to groundwater, creeks, and rivers and are not connected to the sanitary sewer system. These visible reminders encourage simple actions that help protect watercourses, support sensitive aquatic habitat, and contribute to a healthier stormwater system for current and future generations.