The major portion of the annual precipitation in the semi-arid west falls as snow. It piles up in the mountains and forms the main source of the water in the creeks and rivers draining the mountainous areas. Some of these streams flow the year around while others and intermittent, flowing only as long as the snow in the mountains lasts. The water-supply for irrigation, power development, and municipal purposes is derived largely from winter snows. A knowledge of the extent of the snow cover and its water content is, therefore, necessary for the proper utilization of this great natural resource. Forecasts of reasonable accuracy are of major importance for proper distribution of water-supplies and in flood protection.
Measurement of the accumulated snowfall at the end of the precipitation season furnishes an important index as to the probable water-supply to be derived from the snow cover. A system of snow surveying has been developed by which it is possible to measure the depth and water content of the snow cover at the end of the precipitation season. Snow surveys are now being made on the principal watersheds of Utah, California, and Nevada, as well as in parts of Idaho, Oregon, and Washington. These surveys form the basis of water-supply forecasts which are made annually at the beginning of the runoff period.
Clyde, George D., "Circular No. 91 - Establishing Snow Courses and Making Snow Surveys" (1930). UAES Circulars. Paper 81.