Determining ground-water age and flow paths within aquifer systems are essential for calibrating flow and transport models. The Los Alamos National Laboratory and New Mexico Environment Department conducted an isotope and geochemical investigation from October 2004 through February 2006. The investigation evaluated ground-water flow paths and ages of samples collected from alluvial and perched intermediate zones and the upper portion of the regional aquifer primarily beneath the Pajarito Plateau and Jemez Mountains, New Mexico. Water samples were collected at 23 single-screen wells located on the Pajarito Plateau and 27 springs discharging within the Sierra de los Valles and White Rock Canyon, New Mexico. Samples were analyzed for tritium, carbon-14, noble gases (helium-3, helium-4, and neon-22), stable isotopes of carbon, hydrogen, and oxygen, and inorganic solutes. Alluvial ground water is entirely modern (recharged after 1943) based on the tritium/helium-3 dating method. Perched intermediate-depth ground water, ranging in depths up to 600 feet, within the Sierra de los Valles and beneath the Pajarito Plateau, is either entirely modern or a mixture of modern and sub-modern (recharged prior to 1943) components. The regional aquifer is either sub-modern or mixed in age. Analytical results for 100 percent modern ground water suggest that the majority of the Sierra de los Valles springs originated as local precipitation. Significant modern recharge from the Pajarito Plateau to perched intermediate zones and the regional aquifer is supported by occurrence of tritium, nitrate, uranium, chromium(VI) and/or perchlorate. The close similarity in stable isotope ratios between regional wells on the Pajarito Plateau and White Rock Canyon springs containing elevated tritium, nitrate, and/or perchlorate support the hypothesis that the perched intermediate zones provide recharge to the upper portion of the regional aquifer beneath the Pajarito Plateau. The regional aquifer is hydraulically connected to the White Rock Canyon springs.