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.

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Figure 1. Map of State of Oregon 4 2. Map showing annual precipitation in Oregon 5 3. Map of surface-water divides (hydrologic units) and all WATSTORE site locations plotted 4. Map of physiographic regions of Oregon 9 5. Map of tectonic features of Oregon 10 6. Map showing the distribution of Basin-fill and alluvial aquifers 25 7. Map of sampling sites for Basin-fill and alluvial aqu i f ers 26 8. Percentage composition of ions for Oregon groundwater quality sites Basin-fill alluvial aqu i fers 29 9. Map showing distribution of outcrops of the Marine rocks of the Coast Range, and the Volcanic and sedimentary aquifers 31 Descriptive statistics of groundwater quality for the Volcanic and sedimentary aquifers (119 total analyses) Number of samp

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