A water well was drilled recently at the new headquarters site of Mount Rainier National Park, Washington. The headquarters site is in the narrow bedrock-walled, alluvium-floored valley of the Nisqually River. The well was drilled to a depth of 96 feet in a terraced outwash deposit which underlies the site. Two confined aquifers were penetrated but only the lower aquifer was screened and developed.
The well was test pumped at various rates, the highest being 235 gallons per minute. During the first of two pumping tests, the specific capacity decreased abruptly. The decrease may have resulted from increased resistance to water movement caused by shifting of the sand and gravel adjacent to the well screen. The specific capacity of the well probably can be increased by additional development; however, because the well is capable of meeting the production requirements of the National Park Service additional development is not essential.
Ground-water levels in the valley alluvium fluctuate at least 16 feet in response to seasonal variations in recharge.
A sample of water taken from the well after 24 hours of pumping was of excellent chemical quality and is classified as soft.
Future ground-water development probably will be most successful in the central and southeastern parts of the headquarters site where the valley alluvium is thickest.
