High streamflow advisory issued for the Lillooet River watershed

The British Columbia River Forecast Centre has issued a high streamflow advisory for the Lillooet River watershed, including Pemberton, Lillooet Lake and its tributaries. 

A high streamflow advisory is issued when river levels are rising or expected to rise rapidly, but no major flooding is expected. Minor flooding or rising groundwater issues may occur in some low-lying areas.

The rapid melting of the high alpine snow is due to the current province-wide heat wave. Pemberton reached 37 degrees on Monday, and overnight temperatures remained at 14 degrees. 

The Lillooet River watershed consists of unmonitored, very high elevation snow and glacial contributions, which can delay peak flows into the summer months. 

Hot weather remains in the forecast for the upcoming week, with temperatures expected to rise to almost 40 degrees in the Pemberton Valley and high elevations reaching between 12-15 degrees. 

The Lillooet River near the Pemberton hydrometric station has risen to 502 m3/s. The Pemberton Valley Dyking District (PVDD) expects the river to rise to 600 m3/s. 

The good news is that flows are not expected to reach the same levels as last year during the heat dome. 

In 2021, the Lillooet River near Pemberton peaked at 758 m3/s. Last year, temperatures were much hotter than what is currently forecast. Pemberton reached above 40 C for four consecutive days during last year's heat dome, and the highest daily minimum was 17.7 C.

The public is advised to stay clear of fast-flowing rivers and potentially unstable riverbanks during the high-streamflow period.

The River Forecast Centre continues to monitor the conditions and will provide updates as conditions warrant. You can find more information about the River Forecast Centre here.