Mount Currie is bracing for a flood.
That's according to a notice that went out to the community last week, seeking volunteers to lug sandbags around the town and protect some homes against waters rising due to a higher-than-normal snowpack.
"Please take note that hot weather and/or heavy rainfall patterns is predicted for the next few weeks which will bring a risk of possible flooding at the junction of Highway 99 and Rancheree," Mount Currie Chief Lucinda Phillips said in a May 25 bulletin. "In preparation of water going over the road, we are looking for volunteers to start sandbagging to help protect homes and gardens should a flood event occur."
The Birkenhead River was rising as of June 1 and Phillips put out a call to Mount Currie residents to fill up sandbags at the Plumber's Shack on Indian Reserve Number 1 as well as the Salt Shed at Xit'olacw.
The flood risk is the result of a high snowpack in British Columbia's South Coast drainage basin, which encompasses areas such as the Upper Squamish and Pemberton Valleys.
An automated snow-pillow report compiled by the province's River Forecast Centre shows a higher-than-average snowpack at the Tenquille Lake snow station, which is located above the Pemberton Meadows. Snow water levels at that station reached to just under 1,500 millimetres at the beginning of May, a rise of approximately 100 millimetres over the 2010 level.
The average snow water level is 1,100 millimetres, according to the centre, but both this year and last year's totals still reach well below 1,700 millimetres, the maximum level recorded by the centre.
Tenquille Lake is the closest of all snow-pillow stations to the Birkenhead River, which is the only water body that the River Forecast Centre identifies for "increased flood potential" in the whole of the South Coast region.
Such conditions can mean higher water levels in the rivers below but they can also decrease the risk of a forest fire because high snow levels atop the mountains ensure the slopes below stay moist as they melt.
For Mount Currie, however, it could mean flooding similar to what's been experienced for the past ten years.
"We've been informed by certain external parties that the snow is definitely a lot, double the amount we had this same time last year," Phillips said in an interview. "We're just trying to get our head in the game by preparing in the community, doing some sandbags. I don't know the chance of flooding, we're just trying to be prepared."
As Phillips tells it, there's at least eight houses in the old Mount Currie townsite about four kilometers from the Village of Pemberton that get flooded every year. There are also some homes along the Lillooet Lake Road that tend to see flooding.
Two rivers surround the Mount Currie reserve: the Birkenhead and the Lillooet. The Birkenhead reaches from around the Owl Creek area along Pemberton Portage Road until it reaches the community just a short distance from the lower townsite. It then travels alongside Lillooet Lake Road before flowing into Lillooet Lake itself.
Paul Campbell, a geoscientist with the River Forecast Centre, said the Birkenhead faces more risk of flooding than other rivers in its region because it is a "hybrid system," meaning that it can experience peak flows either due to snowmelt in the spring or due to heavy rainfall in the fall and the winter.
The Birkenhead has the added risk of being located next to high elevation terrain, meaning spring melt flows can be significant and cause flooding.
The river typically reaches peak levels in the June to early July period and Campbell said the specific flows would be determined by any weather that the region experiences over the spring snow melt period, which is expected to last the next six weeks.
Environment Canada forecasts rising temperatures for the Pemberton area over the next week or so, with rain expected to continue until Tuesday with lows of six degree Celsius and highs of 19 degrees Celsius. Temperatures are expected to rise two days later to highs of 20 degrees Celsius and lows of 10 degrees Celsius.
