The hydrogeologic framework and geochemistry of the Columbia Plateau aquifer system, Washington, Oregon, and Idaho

Abstract

The Regional Aquifer-System Analysis (RASA) Program was started in 1978 following a congressional mandate to develop quantitative appraisals of the major groundwater systems of the United States. The RASA Program represents a systematic effort to study a number of the Nation's most important aquifer systems, which in aggregate underlie much of the country and which represent an important component of the Nation's total water supply. In general, the boundaries of these studies are identified by the hydrologic extent of each system and accordingly transcend the political subdivisions to which investigations have often arbitrarily been limited in the past. The broad objective for each study is to assemble geologic, hydrologic, and geochemical information, to analyze and develop an understanding of the system, and to develop predictive capabilities that will contribute to the effective management of the system. The use of computer simulation is an important element of the RASA studies, both to develop an understanding of the natural, undisturbed hydrologic system and the changes brought about in it by human activities, and to provide a means of predicting the regional effects of future pumping or other stresses. The final interpretive results of the RASA Program are presented in a series of U.S. Geological Survey Professional Papers that describe the geology, hydrology, and geochemistry of each regional aquifer system. Each study within the RASA Program is assigned a single Professional Paper number, and where the volume of interpretive material warrants, separate topical chapters that consider the principal elements of the investigation may be published. The series of RASA interpretive reports begins with Professional Paper 1400 and thereafter will continue in numerical sequence as the interpretive products of subsequent studies become available.

Increased habitat connectivity homogenizes freshwater communities: historical and landscape perspectives

“…We observed mid‐summer near surface temperatures from 14·5 to 26·8 °C (median = 22·7 °C), suggesting that there is a large thermal gradient that exists in the region, potentially fed by cooler groundwater that rose considerably following construction of dams and canals (Whiteman et al . ). This variable thermal landscape may encourage regional coexistence of both cool‐ and warmwater species: several of the taxa found in contemporary, but not historical periods, included so‐called southern species associated with warmer temperatures (e.g.…”

“…Edmondson () showed that hydrologic alterations changed salinity and species composition in two lakes; however, landscape‐level effects are unknown and may be variable because of erratic groundwater changes (Whiteman et al . ). Canals in the CBP have increased the structural connectivity between some lakes, whilst others have remained isolated, thereby creating differences in connectivity across the landscape and therefore, differences in dispersal opportunities for organisms.…”

The quality of our Nation's waters: groundwater quality in the Columbia Plateau and Snake River Plain basin-fill and basaltic-rock aquifers and the Hawaiian volcanic-rock aquifers, Washington, Idaho, and Hawaii, 1993-2005

“…Sedimentary basin-fill aquifers are present where sediments have accumulated in low-lying basins to form complex, multilayered aquifer systems on top of the regional basalt aquifer. (12) Depth to the water table is 20 to 60 feet in the wells sampled for this study, but depth to the water table can be hundreds of feet in some places.…”

Isotopically‐depleted late Pleistocene groundwater in Columbia River Basalt aquifers: Evidence for recharge of glacial Lake Missoula floodwaters?

“…[7] Together the basalt flows comprise the CRBAs, which consists of three principal hydrogeologic formations (from youngest to oldest: Saddle Mountains, Wanapum, and Grande Ronde Basalts) overlain by the Overburden Aquifer [Whiteman et al, 1994] (Figure 1b). Regional groundwater flow through high permeability interflow zones within the CRBAs occurs dominantly between successive flow units (i.e., parallel to stratiform), while localized flow may occur along vertically oriented fractures and through faults [U.S. Department of Energy (DOE), 1988; Tolan et al, 2007].…”