High Streamflow Advisory – South Coast and Vancouver Island (Maintained)
UPDATED: 11:00 AM December 20, 2018
The River Forecast Centre is maintaining a High Streamflow Advisory for the South Coast and Vancouver Island including:
· Metro Vancouver – including the Serpentine and Nicomekl Rivers and local streams
· Howe Sound – including the Stawamus River and tributaries along the Sea-to-Sky Highway
· Sunshine Coast – including watersheds around Gibsons and Sechelt
· North Shore – including the Seymour River and watersheds around North Vancouver and West Vancouver
· Fraser Valley (North) – including mountainous tributaries from Coquitlam to Harrison
· West Vancouver Island – including tributaries around Gold River, Zeballos, Tofino and surrounding areas
· Central Vancouver Island – including the Sproat and Somass Rivers and areas surrounding Port Alberni
· East Vancouver Island – including tributaries around Campbell River, Courtenay, Parksville, Nanaimo and surrounding areas
· Southern Vancouver Island – including the Cowichan River, Chemainus River and surrounding tributaries
A series of powerful Pacific storms has impacted British Columbia for the past week, with many weather stations recording 200-350 mm of precipitation over that period. Freezing levels have ranged between 1000 to 1500 m resulting in significant snow accumulation over higher terrain. Rivers and creeks on Vancouver Island and the South Coast have been high, but have not resulted in flood levels.
The final storm of this series is currently passing over south-west BC, bringing strong winds and moderate rainfall. Rainfall totals overnight and this morning have been in the 30-100 mm range on Vancouver Island, and 15-40 mm range in the Howe Sound and Metro Vancouver area. Rainfall rates have been easing on Vancouver Island, and are expected to ease on the South Coast later on Thursday.
River levels are expected to rise on Thursday in response to this rainfall. Cumulative rainfall amounts over the past week have made lake-fed river systems the most vulnerable to high flows. On the Sproat River and Somass River near Port Alberni, river levels later on Thursday and into Friday are expected to reach similar or slightly above levels observed this past Tuesday (eg. estimated flows up to approximately 700 m3/s, or a 2-year flow, on the Somass River). Similarly the Cowichan River near Duncan (Water Survey of Canada gauge 08HA011) are expected to rise on Thursday and into Friday up to 300-350 m3/s (between a 2-year and 5-year flow).
Drier weather on Friday will allow for general improvement in river conditions across the region into the weekend.
The River Forecast Centre will continue to monitor conditions and update this advisory as conditions warrant.
Our diking system protects our community.
A High Streamflow Advisory means that river levels are rising or expected to rise rapidly, but that no major flooding is expected. Minor flooding in low-lying areas is possible.
A Flood Watch means that river levels are rising and will approach or may exceed bankfull. Flooding of areas adjacent to affected rivers may occur.
A Flood Warning means that river levels have exceeded bankfull or will exceed bankfull imminently, and that flooding of areas adjacent to the rivers affected will result.
Floods - What To Do
Though governments at every level work to reduce the risk of floods, the first line of defence always rests with the individual. Each of us has a responsibility to protect our homes and families to the greatest extent possible. By planning ahead and taking sensible precautions, you can do your part to minimize flood damage.
Flash or sudden flooding, in which warning time is extremely limited, can result from other causes such as earthquakes, tsunamis or tidal waves, hurricanes, violent storms or bursting of dams. In all cases, local government authorities try to keep residents informed of developments in areas most likely to be affected by flooding. Regular media advisories will recommend actions people should take to limit or prevent disaster. As the need arises, more detailed instructions by municipal or provincial authorities will be given.
Before The Flood
- Ensure that you have a battery-powered radio in working order, with spare batteries, to listen to instructions from your local station.
- Prepare for a minimum of a one week emergency kit that includes food, water and medical supplies in an easy-to-carry container. In addition to the battery-powered radio and spare batteries, it should contain at least the following items:
- Flashlight with spare batteries
- Warm clothing, including waterproof outer garments and footwear
- All necessary medication
- Infant care items
- Personal toiletries
About the Freshet
Annually in May and June, British Columbia experiences a freshet. This occurs when accumulated snow at higher elevations melts, causing river levels to rise.
Due to rainfall and rapid snow melt, a high streamflow advisory may issued for the Lower Fraser River. A high streamflow advisory means that river levels are rising or expected to rise rapidly, but that no major flooding is expected. Minor flooding in low-lying areas, outside of the diking system is possible. Let us answer your questions regarding the freshet and how it affects you. Download our Freshet Fact Sheet.
Check out our Fact Sheets in our Resource Library to better prepare yourself and your family in the event of an emergency.