MOUNT SHASTA'S GLACIERS

Mount Shasta's glaciers hold the largest total volume of ice in California—4.7 billion cubic feet (as measured in 1981, reported in 1986 by Dridger and Kennard). This is important because glaciers are a natural reservoir, with a steady volume of water output throughout dry seasons and droughts. Communities, animals and aquifers rely on this output.

This articles draws from research done by Dr. Slawek Tulaczyg andIan Howat of the University of California at Santa Cruz, which is available on the Internet. Tulaczyg and Howat examined the effects of climate change on Mount Shasta's glaciers.

Mount Shasta's seven glaciers (named Witney, Bolam, Hotlum, Wintun, Watkins, Konwakiton and Mud Creek) and many perennial snow fields supply water into three main river systems: the Shasta River to the northwest, the Sacramento River to the southwest, and the McCloud River to the southeast. Runoff from Mount Shasta is the primary water source for the communities of Mount Shasta, Weed and McCloud, and helps maintain the aquatic environments around the Mountain, including springs, creeks and wetlands.

The Mountain's glaciers have fluctuated greatly over time, decreasing by about half during a protracted drought between 1917 to 1936. However, global warming presents the risk that the glaciers could disappear altogether. Even though Mount Shasta's glaciers are currently growing due to higher moisture levels, this is a temporary phenomenon, the Tulaczyg study predicts that temperature will increase annually (up to 3.8EC) in the next few decades, causing a decrease in snow accumulation.

The study concludes that the Shasta glacier system has no parallels in California. Because of its practical and environmental significance, it is critical to determine its health and develop models to predict its response to future changing climatic conditions.

The ramifications of global warming will affect how much water is available to local communities, as well as to aquatic habitats. Any proposals using large quantities of water (such as the Dannon and Nestle projects—please see the article in this issue on the latter) will need to have contingency plans for drought and global warming as they affect available water, in order to assure that water needed for local communities, aquifers and habitat is protected.