Snow is Canada’s hidden reservoir. Each winter, the precipitation it brings is stored not behind dams, but across mountains, forests and prairies as snowpack. When temperatures rise, that stored water melts and is released gradually, sustaining rivers, groundwater, ecosystems, agriculture and hydropower.
This seasonal storage underpins water security across much of the country. Prairie agriculture depends heavily on mountain snowpack for irrigation. The Great Lakes basin relies on snowmelt to sustain spring inflows that support navigation, ecosystems and freshwater withdrawals. Hydropower systems in British Columbia and Québec depend on snow accumulation and melt timing in upland watersheds.
For decades, scientists and water managers have relied on snow water equivalent (SWE) to measure this winter water reservoir. SWE estimates how much liquid water snowpack would produce if melted instantly. It is physically intuitive and remains central to seasonal water forecasting.
