Crater Lake National Park is on the crest of the Cascade Range in southwestern Oregon. Except for small areas of glacial deposits, the area is underlain by volcanic rocks of Tertiary and Quaternary age. The principal rock types are andesitic and basaltic lavas, pumiceous volcanic flow breccias, tuffs, and airborne and flow pumice. The pumice is an excellent medium for the infiltration of much of the 67 inches of annual precipitation. The pumice and underlying lava flows and pyroclastic material transmit a large quantity of ground water which percolates to the water table and to various spring outlets.
In many areas of the park, the occurrence of perched ground water at altitudes below 6,500 feet is shown by numerous springs that drain water from ground-water bodies perched above the regional water table. Most of the streams and springs in the area flow throughout the year. The quality of the water is excellent. It is soft, has a low mineral content, and contains insignificant amounts of objectionable constituents.
During 1962, test drilling in the northern part of the park failed to locate perched-water bodies capable of supplying quantities of water adequate for proposed facilities. However, test drilling indicated that the regional water table is below an altitude of 4,960 feet and that wells at high altitudes may have to be drilled to depths exceeding a thousand feet to obtain water. Because the water table is at undetermined depth and the existence of productive perched ground-water bodies above the regional water table at a specific site cannot be predicted, the possibility of obtaining productive wells in the area is speculative.
Additional publication details
USGS Numbered Series
Water-resources appraisal of Crater Lake National Park, Oregon
U.S. Dept. of the Interior, Geological Survey, Water Resources Division,