Declining Spring Mountain Snowpack
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Life in Idaho depends on snow. Snow provides soil moisture for the trees in the foresst and sagebrush in the rangelands. Snow provides the majority of river water (1,2) which supports irrigation for agriculture, water for hydro-power generation, and the river flow necessary for recreation, fish, and other animals. Changes in the amount of snow, or snowpack, can negatively affect these vital parts of life in Idaho.
Snowpack has declined slowly over the last 50 years. State and federal scientists measure snowpack by taking a vertical core of the snow from the surface to the ground and measuring how much water is in that core sample. This is referred to snow water equivalent or SWE for short. Scientists in Idaho have been measuring SWE around the state since as early as 1937 and continue to measure SWE |
Snowpack indicator: 1 April snow water equivalent (SWE) for each year relative to the mean of 1971–2000 (normal) for 126 sites in Idaho.
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at many of these same sites. With these long term SWE measurements, the change in snowpack over the last 50 years is clear.
Changes in snowpack is challenging and changing water resource management in Idaho. The following figures show exactly what changes in snowpack have occurred. Figure 1 shows changes in snowpack at the sites from when measurements started (1930s – 1960s depending on the site) to 2010. Blue indicates an increase in snowpack; red indicates a decrease in snowpack.
Decreases in the snowpack later in the season means that there is less snow in the mountains to generate summer river flows. This is bad news for water resources in Idaho because flow in streams and rivers will reach baseflow, or its lowest level of the year, earlier in the summer. So, whether it is a seasonal stream that provides water for a rancher’s cattle that dries out earlier in the summer or less flow in the Snake River to provide power, irrigation, and recreation, livelihoods in Idaho will be impacted.
References:
Changes in snowpack is challenging and changing water resource management in Idaho. The following figures show exactly what changes in snowpack have occurred. Figure 1 shows changes in snowpack at the sites from when measurements started (1930s – 1960s depending on the site) to 2010. Blue indicates an increase in snowpack; red indicates a decrease in snowpack.
Decreases in the snowpack later in the season means that there is less snow in the mountains to generate summer river flows. This is bad news for water resources in Idaho because flow in streams and rivers will reach baseflow, or its lowest level of the year, earlier in the summer. So, whether it is a seasonal stream that provides water for a rancher’s cattle that dries out earlier in the summer or less flow in the Snake River to provide power, irrigation, and recreation, livelihoods in Idaho will be impacted.
References:
- Hamlet, A.F., P.W. Mote, M.P. Clark, and D.P. Lettenmaier. 2005. “Effects of Temperature and Precipitation Variability on Snowpack Trends in the Western United States*.” Journal of Climate 18 (21): 4545–4561.
- Serreze, Mark C., Martyn P. Clark, Richard L. Armstrong, David A. McGinnis, and Roger S. Pulwarty. 1999. “Characteristics of the Western United States Snowpack from Snowpack Telemetry (SNOTEL) Data.” Water Resources Research 35 (7): 2145–2160. doi:199910.1029/1999WR900090.
