The Importance of Snow
Posted: January 28, 2014
Depending on your perspective, the lack of snow cover can be a blessing or a disaster. Less snow reduces energy costs, eases travel and prolongs some outdoor recreation but is devastating to ski enthusiasts and the businesses that rely on them. The impact that a lack of snow cover can have on water supplies around the state is less obvious.
Unlike some western states where snow may account for more than 80% of the annual precipitation, snow typically makes up 10 to 25% of the annual precipitation in Pennsylvania. Although snow is less important than rainfall, the presence of a snow pack in spring can be a very important source of water in the forest. Melting snow forms temporary vernal ponds that serve as a critical habitat for many forest amphibians.
The snow pack that accumulates during an average winter also insulates the soil underneath it keeping the soil largely unfrozen and able to absorb water from melting snow. Since trees and other plants are dormant during early spring, most of the snowmelt water entering the soil infiltrates deep below the surface where it recharges ground water aquifers. When snow cover is lacking, not only is less water available but the soil may also freeze deeper preventing snowmelt or rain from recharging ground water until later in the spring.
Ground water aquifers that are recharged in the spring by melting snow provide water supply wells and streams with a steady source of cool ground water during the long, hot summer. Fish and other stream life have adapted to the increased stream flows in spring and the relatively cool ground water that is supplied to the stream throughout the summer. Without this spring recharge, stream levels may drop and stream temperatures may increase to dangerous levels during the summer. The effects of a lack of snow on water resources can be offset by frequent rainfall during the spring. However, once the growing season begins, the window of opportunity to recharge ground water is lost until the next dormant season.
The next time you are celebrating the warm, snow-free winter weather or cursing old man winter as you shovel snow, consider the important role that snow plays in ensuring water supplies and stream ecosystems throughout the state.
Water Resources Specialist
Renewable Natural Resources
Penn State Extension
Department of Ecosystem Science and Management