Water supply at Los Alamos during 1994. Progress report

Abstract

I ICover illustration: The graph illustrates the changes in water levels observed in the test welki in the main aquifer of the Los Alamos area. These changes indicate declines of as much as 35 feet. Water level changes in pumping well fields are discussed in Section V of this report. An Afirmative Acfion/Equal Opportunity Employer

Geologic Framework of a Groundwater System on the Margin of a Rift Basin, Pajarito Plateau, North‐Central New Mexico

“…More than 50 active and inactive water‐supply and test wells intersect regional groundwater across the Pajarito Plateau (Griggs, 1955, 1964; Cushman, 1965; Cooper et al, 1965; Purtymun et al, 1990, 1995a, 1995b; Purtymun, 1995; Stoker et al, 1992; McLin et al, 1996, 1998; John Shoemaker, Inc., 1999; Koch and Rogers, 2003). Depth to water is greatest at mesa‐top locations in the western part of the plateau (e.g., 375 m, 1245 ft, at Well CdV‐R‐15‐3) and decreases eastward.…”

Development and Application of Numerical Models to Estimate Fluxes through the Regional Aquifer beneath the Pajarito Plateau

“…Based on streamflow data and transient head data, basin‐scale inverse modeling (Keating et al, 2003) indicated that approximately 253 kg s −1 of the gain to the river along this reach originated on the Pajarito Plateau and the Sierra de los Valles. This analysis probably underestimates total recharge on the plateau, in part, because the basin model was calibrated to a lower estimate of aquifer discharge north of Otowi Bridge than is indicated by the streamflow analysis presented in the Part of the reason for the differences between these various estimates of total recharge is that several of the smaller estimates (McLin et al, 1996; Speigel and Baldwin, 1963; Griggs and Hem, 1964) emphasized the southern portion of the plateau (including LANL), which according to our streamflow analysis in the , is discharging less water than the northern portion of the plateau. Although these various estimates are disparate and reflect real uncertainty, they are extremely valuable as bounding values for flow and transport modeling.…”

“…Many authors have identified the Rio Grande as the discharge point for the regional aquifer (Cushman, 1965; Griggs and Hem, 1964; Hearne, 1985; McAda and Wasiolek, 1988; Purtymun and Johansen, 1974; Theis and Conover, 1962). Previous reports have cited a variety of evidence to support this, including streamflow gain along the Rio (Balleau Groundwater, 1995; Purtymun and Johansen, 1974; Spiegel and Baldwin, 1963), measured vertical upward gradients in the vicinity of the Rio Grande (Cushman, 1965; Griggs and Hem, 1964), the presence of flowing wells (McAda and Wasiolek, 1988; McLin et al, 1996; Spiegel and Baldwin, 1963), and springs along the river (McLin et al, 1996). Discharge to the river may occur as lateral flow, upward flow, or as flow from springs in White Rock Canyon.…”

“…Griggs and Hem (1964) estimated the total recharge to the aquifer beneath the Plateau to be between 168 and 216 kg s −1 McLin et al (1996) estimated an upper bound of 192 kg s −1 , based on recovery of water levels in supply wells rested for a period of several months to several years. Using a variety of methods and considering a larger area, Kwicklis and others (2005) estimated total recharge to the Pajarito Plateau of 336 kg s −1 Baseflow gain to the Rio Grande has been used by a number of researchers to estimate total aquifer discharge, both from beneath the plateau and the eastern basin, which presumably approximated total aquifer recharge before significant pumping began.…”

“…They concluded that the total storage loss has been approximately equal to total production in the time period 1949 to 1993, and thus perhaps that there has been no significant net recharge to the well fields during this time. McLin et al (1996) suggested that significant recharge has occurred, since water levels have recovered in wells allowed to rest for a period of several months or several years. The proportion of storage loss that has been replaced by recharge, an unknown quantity, is related to the impact of production on discharge to the Rio Grande.…”