Western Snowpack Not Always a Predictor of Water Supplies

Western Snowpack Not Always a Predictor of Water Supplies

Western snowpack at its peak might not always be the best indicator of the coming summer’s water supplies.

Western snowpack measurements, typically taken on April 1st each year, are used as a predictor of the year’s water resources. A new study from the Desert Research Institute concludes that the predictions might not hold up anymore, based on recent weather patterns.

Snowpack that collects on mountains is vital to water resources, especially in the Western US. As the snowpack melts, it releases water into streams, rivers and lakes, supplying up to 75 percent of water to the American West.

Snow depth measurements are taken at Snow Telemetry (SNOTEL) sites every year on April 1st. The amount of accumulation depends on such factors as moisture content of the soil, air temperature, precipitation patterns, storm frequency, the number of plants in the area and their water use and how much snow runoff feeds groundwater, all of which are in constant flux.

In 2021, although the upper basin of the Colorado River snowpack measured in at 90 percent of average, it translated into only 36 percent of the average runoff amount into Lake Powell. Two unexpected early season heat waves cause rapid melting and ablation - when the snow skips the melting stage and goes right to evaporation - bringing about a quick depletion of the potential water supply before it could reach Lake Powell.

Weather patterns are increasingly being impacted by climate change, making predictions about water resources trickier. The recent massive atmospheric river-driven rainstorms in California are a good example. The forecast was for a drier “la niña” winter, then the rains came, causing widespread flooding across the state.

So, basically, it’s gonna be hot or cold, depending on the weather. Sometimes, all we can do is wait and see and hope the meteorologists get it right.