Open Drainage
The City of Chilliwack’s unique blend of urban, rural, and agricultural areas makes open drainage a vital part of its infrastructure.
Open drainage refers to a visible, above-ground system of ditches, swales, creeks and streams used to manage stormwater and surface water runoff. Unlike underground (closed) drainage systems, open drainage includes features such as roadside ditches, field drains, and watercourses. These systems help direct water safely away from roads, properties, and agricultural lands.
Types of Open Drainage Systems
Chilliwack has approximately 730,000 meters of open watercourses, including:
- Roadside ditches
- Agricultural drains
- Natural watercourses
- Stormwater swales
Importance of Open Drainage
Open drainage systems provide several essential services:
- Preventing flooding: Directing excess rainwater away from streets and properties.
- Protecting infrastructure: Reducing erosion and damage to roads, culverts, and foundations.
- Supporting agriculture: Ensuring effective drainage for crops in low-lying areas.
- Promoting water quality: Filtering sediment and debris before water enters streams and rivers.
- Environmental stewardship: Supporting ecosystems and wetlands through natural water flow.
- Storage: Open watercourses provide more flood storage than pipes. Increased storage volume decreases the risk of overland flooding.
Why Open Drainage Maintenance is Needed
Key challenges that require regular maintenance:
- Lack of riparian cover: Many watercourses in the Agricultural Land Reserve lack a canopy of shrubs or trees, allowing aquatic vegetation to overgrow.
- Slow-moving water: Flat terrain results in slow moving water, as well as vegetation and sediment buildup, rather than being flushed out naturally.
- High nutrient input: Agricultural fertilizers can promote excessive growth of aquatic plants in adjacent watercourses.
Drainage Maintenance Regulations
Federal: Department of Fisheries and Oceans (DFO) – Oversees fish habitat under the Federal Fisheries Act
Provincial: Ministry of Environment – Enforces the Water Act and the Fish Protection Act
Regulatory Process to Lawfully Conduct Channel Maintenance
Every year, in order to maintain compliance with both federal and provincial legislation, prior to undertaking channel maintenance works, The City must prepare and submit the following documents:
- Provincial Water Sustainability Act (WSA) application/notification for 25-45 channel segments
- Request for Review application to The Department of Fisheries and Oceans (DFO) for 25-45 channel segments
- Species at Risk Act (SARA) application to DFO re Salish Sucker and Oregon Spotted Frog
- Fish salvage application to the Ministry of Water, Land, and Resource Stewardship (MWLRS)
- Fish salvage application to DFO
- Amphibian salvage application to MWLRS re endangered Oregon Spotted Frog
- Mitigation plan for encounters with protected/endangered species such as Barn Owl, Coastal Giant Salamander, Western Painted Turtle etc.
Upon completion of works, The City must then prepare and submit monitoring reports associated with the approvals above.
Environmental Mitigation & Compensation Measures
Drainage maintenance must follow over 30 terms and conditions provided by DFO, including:
- Fish salvage prior to ditch cleaning
- Silt and sediment control measures
- Streamside planting as compensation
- Monitoring by a qualified environmental professional
- Submission of a post-work environmental monitoring report
When is Drainage Maintenance Conducted?
- Fish-Bearing Systems:Must be conducted within the Fisheries Work Window, typically between August 1 – September 15. This avoids interfering with salmonid spawning, eggs, or fry.
- Non-Fish-Bearing Systems: Maintenance periods are more flexible and can be done outside of the critical fish periods.
- Emergency Work: May be conducted outside of regular windows as needed, with proper approvals.
Prioritizing Drainage Maintenance
Maintenance schedules are determined by:
- Fisheries work window availability
- A 3 to 7-year maintenance cycle
- Field inspections and assessments by City staff
- Available budget, staff, and equipment
| Attachments | |||
| Description | Date | File Size | |
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Frequently Asked Questions - Open Drainage | 2025-07-17 | 200KB |