By Steve Hubrecht
[email protected]

Lake Windermere is ice-free, bicycles are zipping down the streets of Invermere, and while nobody is planting seeds just yet, local backyard gardeners are starting to mull over just what to grow in their vegetable patch this summer. In other words: it’s springtime. 

At least, it’s springtime bottom of the valley. Up in the high country, though, there’s still plenty of snow. In fact, according to provincial government data, there’s 23 per cent more spring snowpack than normal.

The B.C. Ministry of Forests, Lands and Natural Resource Operations (FLNRO)’s River Forecast Centre released a snow survey and water supply bulletin in March that noted that, as of early March, snowpack in the Upper Columbia River area (which includes Canal Flats to Golden to Kinbasket Lake to Revelstoke) is at 123 per cent of its normal level for that time of year. The data for the bulletin was collected from BC Hydro weather stations scattered throughout the province.

The bulletin emphasized that this the highest spring snowpack for the Upper Columbia since 1996. “Communities in the Upper Columbia will be at risk for flooding through the freshet and may remain at risk into late June or even July due to significant high elevation snow pack,” read the bulletin, later adding, “the combination of normal to above normal Mar. 1 snow pack, La Niña conditions forecast to persist through spring, and seasonal weather forecasts that predict cooler conditions for the province means an elevated risk for freshet-related flooding.” 

The bulletin, however, did go on to outline that “snowpack is also only one factor related to freshet flood risk. Weather conditions from April through June determine the timing, magnitude and rate of snow melt, and heavy rainfall events can exacerbate the situation. Flooding is possible in years with normal or even below-normal, snowpack. Conversely, high snowpack does not typically lead to flooding without significant contributing weather during the snow melt season.”

Another bulletin from the River Forecast Centre was due out in early April, just as the Pioneer went to press with the Apr. 14 issue, but the Pioneer was unable to get a copy prior to deadline.

Columbia Lake Stewardship Society board member Bill Thompson offered more insight on what the bulletin means here in the Columbia Valley.

Thompson noted that an above-average volume of water accumulating in the snowpack means more water for groundwater recharge and for ponds, lakes, and reservoirs, which he pointed out is good news for irrigation systems, water utilities, the tourism sector, and aquatic species. 

“It does not necessarily mean flooding, though that is not a reason to disregard caution. Flooding depends on the rate at which water is released from the snowpack and that in turn depends mainly on temperature conditions during late May and early June. A period of abnormally cool temperatures at the beginning of the melt season followed by an extended heat wave is a common cause of flooding,” said Thompson. “It can be further complicated by the timing and amount of rainfall.  Heavy rainfall events at the end of May during each of the past two years dumped additional water on an already ripe snowpack that gave rise to localized flooding and led to rapid rises in both Columbia Lake and Lake Windermere. If temperatures progress at near normal rates prior to and during this critical period and there are no heavy rainfall events, the runoff will generally be contained in the channel.”

Thompson cautioned against reading too much into the bulletin, in part because in the Spillimacheen-to-Canal Flats subregion of the Upper Columbia area, there is only one (mid-level) weather station to monitor the snowpack. This is located in Fairmont Hot Springs and operated by the Regional District of East Kootenay (RDEK) as part of the Fairmont Flood mitigation program. 

The next closest weather station — one which is operated by BC Hydro — is at Floe Lake in Kootenay National Park. “It is tracking at near 20 percent above normal and may be the source of the estimate,” said Thompson, but he added that water from that location drains into the Kootenay River watershed, not into the Columbia River watershed.

“In short, flooding, if it occurs, will be largely determined by the weather events of May and June,” concluded Thompson.

Here in the Columbia Valley, when spring runoff-related flooding and debris flows do occur, they tend to hit most powerfully in Fairmont Hot Springs. The community and surrounding area has been hit with significant flooding or debris flows — and evacuations alerts or orders for local residents — three times in the past decade: in 2012, in 2020, and last year in 2021.

When the Pioneer spoke with Regional District of East Kootenay (RDEK) Engineering Services Manager Brian Funke last year about the flooding in the Fairmont area, Funke echoed Thompson’s opinions that weather events — specifically heavy rainfall or heavy snowfall late in spring — are a big factor (if not the biggest factor) in determining flooding and debris flows in the Columbia Valley, especially in Fairmont.

“When (Fairmont Creek and Cold Spring Creek) get significant moisture — snow, rain, or worse yet rain on snow – they can really get material (boulders, cobbles, dirt and other natural debris) moving down the slope within the creek channel,” Funke had said, noting that the 2021 Fairmont floods came after a 1-in-25 year rainfall and that the debris flow and flooding in 2012 was mostly the result of rain falling on melting snow.  Rain-on-snow events are problematic, Funke had added “since the melting snow is already saturated (with water). Once a big rainfall hits it, all of sudden you’re getting a lot more moisture running down the slopes of the creek bed, and a lot more water going into the creek channel.”

RDEK Area F Director Susan Clovechok, who had seen the bulletin, also told the Pioneer that, from what she understands, that a larger than normal snowpack is only likely to result in flooding or a debris flow if there is a major weather event.

“So, of course, every time there is a rainstorm at night in May or June, it keeps me awake at night,” she said. “But without that kind of big storm or a sudden temperature spike (which could rapidly increase the rate of snow melting) it’s likely that the snow will just melt away at a normal pace, even if there is more of it up in the mountains.”