New Mexico Geological Society Annual Spring Meeting — Abstracts

During the mid 1990’s, New Mexico Environment Department’s Department of Energy Oversight Bureau (the Bureau) recognized that there was not an adequate inventory and characterization of local springs and surface-water resources in the Los Alamos area. The Bureau identified surficial water resources extending from Guaje Canyon to Frijoles Canyon. The survey resulted in the discovery of 89 undocumented perennial and ephemeral springs. Perennial surface-water flow from both newly discovered and previously identified springs were documented and monitored to determine changes in flow rates and stream conditions in response to wet and dry periods. A variety of information and data were collected including coordinates, geologic discharge units, field chemistry parameters, and in some cases, water-quality constituents, tritium, and stable isotopes. Springs discharge from shallow, intermediate, and deep aquifers composed of sedimentary and volcanic rock units. The shallow-perched perennial springs primarily reside in the western portion of the Pajarito Plateau and the Sierra de los Valles. Ground-water ages vary within each aquifer; however, the youthful waters tend to be shallow versus older waters occurring at greater depths. Estimated recharge of area of precipitation elevations, as indicated by stable-isotope data, for the shallow-perched and intermediate/regional springs range from about 2300 to 2900 m and 2100 to 2400 m, respectively. As a result of this work, a more complete and accurate understanding of hydrologic conditions in the Los Alamos area has been gained, which is critical to the management and protection of water resources