Our Flood Protection System

Flood Protection Works Prior to 2009

Prior to the November 2009 flood, the following flood protection works were in place (see map):


(Click on the image to enlarge)

North of the Cowichan River:

  1. Cowichan River Dike
  2. JUB Sewage Lagoon Outer Dike (Pt 1 and Pt 2)
  3. Quamichan Dike

South of the Cowichan River:

  1. Cowichan River South Side Dike
  2. South Side Spur Dike
  3. Hatchery Dike

There were also several pump stations on north of the Cowichan River that pumped water over the dikes:

  • Lakes Rd Flood Pump Station (North Cowichan)
  • Beverly Street Flood Pump Station (North Cowichan)
  • Marchmont Flood Pump Station (City of Duncan)

The 2009/2010 Flood

In mid 2009, the Integrated Flood Management Plan (IFMP) was completed. It predicted higher flood levels and outlined the actions needed to reduce the flood risk. The plan recommended the raising of existing dikes, construction of new dikes, and regular removal of gravel and log jams in the Cowichan River.

In November 2009, shortly after the completion of the IFMP, a 7-year flood event overtopped Lakes Road and flooded the JUB Sewage Treatment Plant (STP) causing flooding in a portion of the urban core.  The flood resulted in the evacuation of 300 homes and long-term support was required for 121 families with response costing approximately $810,000. A second flood occurred in January of 2010, which did not cause damage to the urban core, but did cause internal flooding within the JUB STP. 


November 2009 flood, Beverly Street (Click to enlarge)

While flooding had occurred in the past, the November 2009 flood was significant in terms of the water levels and impacted area. The reason why this 7-year flood caused such extensive flooding was partially because of accumulation of gravel deposits and formation of log jams in the lower reaches of the Cowichan River. This drove water levels higher, resulting in extensive flooding in parts of North Cowichan, the City of Duncan, CVRD Areas D and E, and Cowichan Tribes Reserve lands (hereafter the urban core).

Since the floods in 2009 and 2010, North Cowichan, the City of Duncan, the CVRD and Cowichan Tribes, have been implementing the IFMP. Flood protection measures were completed in several phases (Tiers) and have been implemented to protect the urban core from future flood events up to at least the 200-year return period flood event.

What Flood Protection Measures Have Been Implemented?

The map below shows the extent of the flood protection works protecting the urban core. Some of the flood protection works existed prior to the 2009 flood. Most were constructed after the 2009 flood.

Flood protection works constructed since the November 2009 flood (Click to enlarge)

The projects undertaken after the 2009 flood were undertaken in several phases. They are:

  1. Phase 1: Shown in yellow
  2. Phase 2: Shown in green (north of the Cowichan River) and purple (south of the Cowichan River)
  3. Phase 3: Shown in red (north of the Cowichan River) and orange (south of the Cowichan River)

Areas that will still flood are shown in light blue. Areas that used to flood but that are now protected are shown as follows:

  1. North Cowichan: Green shading
  2. City of Duncan: Blue shading
  3. Cowichan Tribes and CVRD: Orange shading

Phase 1

The first phase of the flood protection works involved undertaking the following projects:

  1. Removal of a major log jam and gravel deposit in the Cowichan River located in the vicinity of the JUB STP outfall pipe (Figure 2).
  2. Raising the JUB STP berms and registration as dikes (Figure 3).
  3. Raising Tzhouhalem Road.
  4. A new dike along the north side of Tzouhalem Rd behind the Petro Can Gas Station.
  5. Upgrading the City of Duncan’s Marchmont Flood Pump Station to increase its pumping capacity. 

 
Sediment and log jam at JUB STP Outfall - Before and After (Click to enlarge)

Phase 2

The second phase of the flood protection works involved construction of the following projects north and south of the Cowichan River:

North of the Cowichan River:

  1. The Lakes Road Dike and Stop Log Floodwall
  2. The Beverly Street Dike (Figure 4)
  3. The York Road Flood Pump Station
  4. A floodwall at Quamichan Village to prevent the confluence of the Cowichan River from continuing its migration to the North and East, protecting Quamichan Village and access road to the village (Figure 5)

South of the Cowichan River:

  1. The South Side Spur Dike (raised and armoured)
  2. The Connector Dike
  3. The Mission Rd Dike
  4. The Hatchery Rd setback dike

 
Beverly St Dyke and Quamichan Village Floodwall (Click to enlarge)

Phase 3

The third phase of flood protection works involved the following projects north of the Cowichan River in and around the Somenos Basin, and adjacent to the Cowichan River immediately north and south of the River on Cowichan Tribes land:

North of the Cowichan River in and around the Somenos Basin:

  1. The Trans-Canada Highway dike, along the east side of the Highway from Beverly Street to south of Holmes Creek
  2. The Canada Ave Flood Pump Stations, which pumps rainfall runoff that accumulates in the urban core behind the dikes over the dikes
  3. The Canada Avene Floodwall from the Canada Avenue Flood Pump Station, running south to north along the east side of Canada Ave, and then east to west south of Philip Street to high ground near the Berkley Sanitary Pump Station
  4. The Rosewood Ave Dike
  5. The Seine Rd Flood Protection Works (Berm)

Adjacent to the Cowichan River immediately north and south of the River on Cowichan Tribes land:

  1. Dike A along the north east bank of the River from Allenby Rd to the rail bridge (Black Bridge)
  2. Dike B along the north bank of the River from the rail bridge (Black Bridge) to the Trans-Canada Highway
  3. Floodwall C south of the River from Allenby Rd to the rail bridge (Black Bridge). The flood wall is set back from the River.
  4. Dike D along the south bank of the River from the rail bridge (Black Bridge) to the Trans-Canada Highway.

 
Trans Canada Hwy Dike and Canada Ave Pump Station (Click on the image to enlarge)