Flood Response Today
Small localized flooding problems continue to occur and are dealt with by the local jurisdiction where the localized flooding occurs. Typically, during larger floods, North Cowichan opens up an Emergency Operations Centre (EOC) to manage flooding within North Cowichan. North Cowichan designates staff to undertake flood watch activities and monitor water levels and weather forecasts. Usually, the CVRD also activates its EOC to deal with localized flooding in the electoral areas and to help coordinate flood protection activities of local jurisdictions and act as a liaison between the local jurisdictions and the Provincial EOC.
North Cowichan has installed water level monitoring equipment to measure water levels in the flood plain. Sensors are located at the JUB Outfall, Lakes Rd Flood Pump Station, Beverly St Flood Pump Station, and Canada Ave Flood Pump Station. Water levels are monitored every minute, digitally charted, and available to staff via our Supervisory Control and Data Acquisition System. This allows staff to see what the water levels are at any given time at key locations around the urban core. Staff is also able to observe the rate of rise in water levels to better gauge when to mobilize crews to implement any flood protection measures that may be required so that staff can see the rate of water rise and respond accordingly.
Despite the installation of the flood protection infrastructure noted above, there are still actions that must be taken if floodwaters get high enough at each of the locations discussed below.
- Tzouhalem Rd: Even though floodwaters cannot flow down Tzhouhalem Rd into the urban core due to the flood protection works, the road may need to be closed at the Tzouhalem Rd bridge and traffic re-routed up Jaynes Rd to Lakes Rd.
- Lakes Rd: If water levels get high enough it may be necessary to close Lakes Rd at the Lakes Rd bridge to install the stop log floodwall to prevent floodwater from flowing down Lakes Rd and into the urban core. If this happens, southbound traffic on Lakes Rd will be re-directed northbound on Lakes Rd to Herd Rd.
- Trans Canada Hwy: If water levels get high enough it may be necessary to close part or all of the Trans-Canada Highway north of Beverly St in order to install a flood barrier across the highway. This will prevent floodwaters in the Somenos Marsh area from flowing across the highway into the urban core. Because the highway is sloped down from west to east, lanes would be closed as the flood water rises, starting with the north-bound lanes, with the south-bound lanes made alternating. If it is necessary to close the highway entirely, southbound traffic will be detoured to Somenos Rd.
- Canada Ave: If water levels get high enough it may be necessary to close Canada Avene and install a barrier to stop waters from the Somenos Marsh area from flowing down Canada Ave and into the urban core. The north-bound lane, just north of the Canada Ave floodwall will usually flood first and may necessitate closing the north-bound lanes. The Municipality recently cleaned the ditch along the east side of Canada Ave to help take water away and there are plans to block culverts and do temporary pumping to mitigate this issue. The Municipality plans to increase the elevation of Canada Ave in the near future to stop the more frequent flooding of Canada Ave. During more extreme floods though, Canada Ave will still need to be closed. When Canada Ave is closed southbound traffic is directed to Sherman Rd and northbound traffic is directed to Beverly St or southbound on Canada Ave.
- Mary St: If water levels get high enough it may be necessary to close Mary St when the road floods.
- Rosewood Ave: If the water level behind the Rosewood Dike gets high enough, the Municipality will install a pump to pump water over the dike.
- Siene Rd: If the water level behind the Seine Rd Berm gets high enough, the Municipality will pump water over the berm.
- Pinson's Corner (at intersection of Crofton Road and Chemainus Road): If the Chemainus River gets high enough, it will overtop the road just past the bridge. At times, the road may become impassable and require a traffic detour.
River Sediment Removal
Sediment accumulation in the lower reaches of the Cowichan River can contribute to more extreme flooding for any given rainfall event as sediment levels increase over time. In 2010, the Joint Utility Board removed about 10,000 m3 of gravel in the vicinity of the treatment plant outfall. In 2013, the Province provided $1,000,000 in funding to remove sediment from the Cowichan River. Sediment was removed at the rail bridge (the Black Bridge) and in the North Arm of the Cowichan River. Since 2013, Cowichan Tribes has received money from the Federal government to remove gravel from the River.
The CVRD has been working on a long term sediment management strategy to manage gravel accumulation and log jams in the lower reaches of the Cowichan River in recognition of the fact that gravel accumulation and log jams can affect the severity of flooding in the Cowichan.
Log jam and gravel deposit generated during November 2009 flood.