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At least 703 records · Page 39Linked to original sources
USGS2024

Groundwater model of the Harney Basin, southeastern Oregon

Groundwater development, mainly for large-scale irrigation, has increased substantially in the Harney Basin of southeastern Oregon since 2010. Concurrently, some areas of the basin experienced groundwater-level declines of more than 100 feet, and some shallow wells have gone dry. The Oregon Water Resources Department has limited new groundwater development in the basin until an improved understanding of the groundwater-flow system is available. The groundwater resources report by Gingerich and others (2022, U.S. Geological Survey Scientific Investigations Report 2021–5103, https://doi.org/10.3133/sir20215103 ) provides that understanding. This report describes the development of a numerical groundwater-flow model that can be used as a tool to help improve that understanding. The Harney Basin Groundwater Model was developed using the finite-difference groundwater-modeling software U.S. Geological Survey modular finite-difference groundwater-flow model (MODFLOW 6) and associated Python pre- and post-processing routines. The groundwater model encompasses the entire 5,240-square-mile Harney Basin and adjacent areas and is calibrated to the hydrologic conditions from 1930 to 2018. The model has a uniform grid consisting of 78,064 nearly square cells, each covering 2,005 by 2,007 feet (about 92 acres) and has 10 layers (780,640 total cells) representing the vertical distribution of hydrogeologic units. The results from the calibrated model simulations indicate that groundwater pumpage exceeded recharge since about the mid-1980s, resulting in an estimated net cumulative depletion of groundwater storage (discharge minus recharge) of about 840,000 acre-feet and also indicated declines in groundwater evapotranspiration and spring and stream discharge. Model simulations show as much as 100 feet of groundwater-level decline in some areas and more than 40 feet of decline in widespread areas in recent decades. Model simulations are consistent with field observations of groundwater levels through time.

Oregon↗
USGS1993

Historic and prehistoric earthquakes near Klamath Falls, Oregon

Earthquakes have rocked the Klamath Falls in the past will continue to do so in the future. Scientists estimate the likelihood of future damaging earthquakes in an area by examining the area's past record of earthquakes and by evaluating the area's earthquake potential in relationship to its geologic setting. To supplement the historic catalog, which often covers only a short time span, they also attempt to identify prehistoric earthquakes preserved in the rocks and sediments of the area. The conclusion drawn from such studies in the Klamath Falls area is that earthquakes in the 4-6 magnitude range, which are capable of light to moderate damage, occur on the order of one or more every few decades. Even a major earthquake in the 7+ magnitude range cannot be ruled out at some future time. However, the area's historic record, which goes back only about 100 yrs, is too short to estimate the frequency of such large shocks. This article is a brief summary of the geologic setting and the historic and prehistoric record of earthquakes in Klamath Falls and the surrounding area.

Oregon↗
USGS2009

Evaluation of hazardous faults in the intermountain west region: Summary and recommendations of a workshop

The U.S. Geological Survey’s (USGS) Earthquake Hazards Program (EHP) has the responsibility to provide nationwide information and knowledge about earthquakes and earthquake hazards as a step to mitigating earthquake-related losses. As part of this mission, USGS geologists and geophysicists continue to study faults and structures that have the potential to generate large and damaging earthquakes. In addition, the EHP, through its External Grants Program (hereinafter called Program), supports similar studies by scientists employed by state agencies, academic institutions, and independent employers. For the purposes of earthquake hazard investigations, the Nation is geographically subdivided into tectonic regions. One such region is the Intermountain West (IMW), which here is broadly defined as starting at the eastern margin of the Rocky Mountains in New Mexico, Colorado, Wyoming, and Montana and extending westward to the east side of the Sierra Nevada mountains in eastern California and into the Basin and Range-High Plateaus of eastern Oregon and Washington. The IMW contains thousands of faults that have moved in Cenozoic time, hundreds of which have evidence of Quaternary movement, and thus are considered to be potential seismic sources. Ideally, each Quaternary fault should be studied in detail to evaluate its rate of activity in order to model the hazard it poses. The study of a single fault requires a major commitment of time and resources, and given the large number of IMW faults that ideally should be studied, it is impractical to expect that all IMW Quaternary faults can be fully evaluated in detail. A more realistic approach is to prioritize a list of IMW structures that potentially pose a significant hazard and to focus future studies on those structures. Accordingly, in June 2008, a two-day workshop was convened at the USGS offices in Golden, Colorado, to seek information from representatives of selected State Geological Surveys in the IMW and with knowledgeable regional experts to identify the important structures for future studies. Such a priority list allows Program managers to guide the limited resources toward studies of features that are deemed to potentially pose the most serious hazards in the IMW. It also provides the scientific community with a list of structures to investigate because they are deemed to pose a substantial hazard to population centers or critical structures. The IMW encompasses all or large parts of 12 states, including Arizona, New Mexico, extreme west Texas, Colorado, Utah, Nevada, eastern California, eastern Oregon, eastern Washington, Idaho, western Wyoming, and western Montana. In Utah, and more recently in Nevada, geoscientists have taken steps to evaluate geologic data related to well-studied faults and to develop a statewide priority list of hazardous structures. In contrast to Utah and Nevada, the other IMW states contain substantially fewer Quaternary faults, so there have not been any previous efforts to develop similar priority lists. This workshop was organized to address this matter and create a more balanced perspective of priorities throughout the entire IMW region. Because working groups and workshops had already been convened to specifically deal with Quaternary fault priorities in Utah and Nevada, this workshop specifically emphasized structures outside of these two states.

Arizona, California, Colorado, Idaho, Montana, Nev↗
USGS2017

9000 years of salmon fishing on the Columbia River, North America

A large assemblage of salmon bones excavated 50 yr ago from an ???10,000-yr-old archaeological site near The Dalles, Oregon, USA, has been the primary evidence that early native people along the Columbia River subsisted on salmon. Recent debate about the human role in creating the deposit prompted excavation of additional deposits and analysis of archaeologic, geologic, and hydrologic conditions at the site. Results indicate an anthropogenic source for most of the salmonid remains, which have associated radiocarbon dates indicating that the site was occupied as long ago as 9300 cal yr B.P. The abundance of salmon bone indicates that salmon was a major food item and suggests that migratory salmonids had well-established spawning populations in some parts of the Columbia Basin by 9300-8200 yr ago. ?? 2004 University of Washington. All rights reserved.

Quaternary Research↗
USGS2014

ShakeAlert—An earthquake early warning system for the United States west coast

Earthquake early warning systems use earthquake science and the technology of monitoring systems to alert devices and people when shaking waves generated by an earthquake are expected to arrive at their location. The seconds to minutes of advance warning can allow people and systems to take actions to protect life and property from destructive shaking. The U.S. Geological Survey (USGS), in collaboration with several partners, has been working to develop an early warning system for the United States. ShakeAlert, a system currently under development, is designed to cover the West Coast States of California, Oregon, and Washington.

California, Oregon, Washington↗
USGS2010

Relation of urbanization to stream habitat and geomorphic characteristics in nine metropolitan areas of the United States

The relation of urbanization to stream habitat and geomorphic characteristics was examined collectively and individually for nine metropolitan areas of the United States?Portland, Oregon; Salt Lake City, Utah; Denver, Colorado; Dallas?Forth Worth, Texas; Milwaukee?Green Bay, Wisconsin; Birmingham, Alabama; Atlanta, Georgia; Raleigh, North Carolina; and Boston, Massachusetts. The study was part of a larger study conducted by the U.S. Geological Survey from 1999 to 2004 to examine the effects of urbanization on the physical, chemical, and biological components of stream ecosystems. The objectives of the current study were to determine how stream habitat and geomorphic characteristics relate to different aspects of urbanization across a variety of diverse environmental settings and spatial scales. A space-for-time rural-to-urban land-cover gradient approach was used. Reach-scale habitat data and geomorphic characteristic data were collected once during low flow and included indicators of potential habitat degradation such as measures of channel geometry and hydraulics, streambed substrate, low-flow reach volume (an estimate of base-flow conditions), habitat complexity, and riparian/bank conditions. Hydrologic metrics included in the analyses were those expected to be altered by increases in impervious surfaces, such as high-flow frequency and duration, flashiness, and low-flow duration. Other natural and human features, such as reach-scale channel engineering, geologic setting, and slope, were quantified to identify their possible confounding influences on habitat relations with watershed-scale urbanization indicators. Habitat and geomorphic characteristics were compared to several watershed-scale indicators of urbanization, natural landscape characteristics, and hydrologic metrics by use of correlation analyses and stepwise linear regression. Habitat and geomorphic characteristics were related to percentages of impervious surfaces only in some metropolitan areas and environmental settings. The relations between watershed-scale indicators of urbanization and stream habitat depended on physiography and climate, hydrology, pre-urban channel alterations, reach-scale slope and presence of bedrock, and amount of bank stabilization and grade control. Channels increased in size with increasing percentages of impervious surfaces in southeastern and midwestern metropolitan areas regardless of whether the pre-existing land use was forest or agriculture. The amount of enlargement depended on annual precipitation and frequency of high-flow events. The lack of a relation between channel enlargement and increasing impervious surfaces in other metropolitan areas was thought to be confounded by pre-urbanization hydrologic and channel alterations. Direct relations of channel shape and streambed substrate to urbanization were variable or lacking, probably because the type, amount, and source of sediment are dependent on the phase of urbanization. Reach-scale slope also was important for determining variations in streambed substrate and habitat complexity (percentage of riffles and runs). Urbanization-associated changes in reach-scale riparian vegetation varied geographically, partially depending on pre-existing riparian vegetation characteristics. Bank erosion increased in Milwaukee?Green Bay and Boston urban streams, and bank erosion also increased with an increase in a streamflow flashiness index. However, potential relations likely were confounded by the frequent use of channel stabilization and bank protection in urban settings. Low-flow reach volume did not decrease with increasing urbanization, but instead was related to natural landscape characteristics and possibly other unmeasured factors. The presence of intermittent bedrock in some sampled reaches likely limited some geomorphic responses to urbanization, such as channel bed erosion. Results from this study emphasize the importance of including a wide range of landscape variables at m

Scientific Investigations Report↗
USGS1995

Tectonic setting of the Portland-Vancouver area, Oregon and Washington: Constraints from low-altitude aeromagnetic data

Seismic activity in the Portland-Vancouver metropolitan area may be associated with various mapped faults that locally offset volcanic basement of Eocene age and younger. This volcanic basement is concealed in most places by young deposits, vegetation, and urban development. The U.S. Geological Survey conducted an aeromagnetic survey in September 1992 to investigate the extent of these mapped faults and possibly to help identify other seismic and volcanic hazards in the area. The survey was flown approximately 240 m above terrain, along flight lines spaced 460 m apart, and over an area about 50 × 50 km. These magnetic data indicate a pronounced northwest-striking magnetic lineation east of the Willamette River in downtown Portland associated with a fault concealed beneath Quaternary sedimentary deposits and previously inferred from shallow well data. The magnetic lineation confirms the existence of the fault and suggests that it has had a prolonged history: (1) Although well data indicate <200 m of vertical offset of underlying volcanic basement, models based on the aeromagnetic data from downtown Portland suggest reverse faulting with up to 1 km of offset deeper in the section. (2) The magnetic lineation associated with this fault extends southeast to the Clackamas River drainage, a distance of 50 km and considerably beyond the mapped extent of the fault. A northwest-striking magnetic anomaly located southwest of the Tualatin Mountains corresponds closely with another mapped fault and with mixed reverse and strike-slip faulting during a seismic swarm (M ≤ 3) in 1991. We believe these and other anomalies in the aeromagnetic data reflect the Portland Hills fault zone, believed to be the southwestern boundary of a structural basin now occupied by Portland and Vancouver. The postulated northeastern boundary of the basin, the Frontal fault zone, is also evident, although less well represented in the aeromagnetic data. Aeromagnetic anomalies, geologic mapping, and earthquake focal-plane solutions demonstrate a complex deformational history in the Portland-Vancouver area since middle Miocene time that includes elements of compression, extension, and dextral slip. These complexities reflect Portland-Vancouver's unique position within a north-south transition in tectonic styles along the Cascadia margin, from compressional in the north to extensional in the south.

Oregon, Washington↗
USGS1996

Estimated water use and general hydrologic conditions for Oregon, 1985 and 1990

Water-use information is vital to planners, engineers, and hydrologists in water resources. This report is a compilation of water-use information for Oregon for calendar years 1985 and 1990. The report presents water-use data by geographic region for several categories of use, including public supply, domestic, commercial, industrial, mining, thermoelectric power, hydroelectric power, live-stock, irrigation, reservoir evaporation, and wastewater treatment. Hydroelectric power is the only instream use discussed; all other uses are considered offstream. The Appendix presents 1985 and 1990 data by region and by drainage basin for the previously mentioned categories of use. The Cascade Range divides Oregon into two distinct climatic zones. The area west of the Cascade Range has an average annual precipitation that ranges from 40 to 200 inches, and precipitation in the area east of the Cascade Range ranges from 10 to 20 inches. The differences in precipitation and geology have an effect on the sources, uses, and amounts of water withdrawn. Most of the large public-supply systems west of the Cascade Range rely on surface water, whereas many of the large public-supply systems east of the Cascade Range use on wells or springs. Irrigators west of the Cascade Range rely primarily on nearby surface- water sources; however, irrigators east of the Cascade Range use primarily surface water that commonly is delivered from distant sources through irrigation ditches. A variety of methods was used to estimate water-use information. Most withdrawals for public-water suppliers were metered; however, irrigation withdrawals usually were estimated by using information on crops, climate, application efficiencies, and conveyance losses. The accuracy of the estimated total withdrawal values for public supply was estimated to be within 4 percent of the values that would be obtained if all public-supply withdrawals were metered. Total withdrawals for irrigation were estimated to be within 40 percent of metered irrigation withdrawals. The estimates-of-error are presented to show the relative, rather than absolute, accuracy of the data for each water-use category. A total of 8,400 million gallons of water per day was withdrawn in Oregon during 1990, about 1,900 million gallons per day more than the 6,500 million gallons per day withdrawn in 1985. Whereas actual water use increased in 1990, the major differences between 1985 and 1990 were attributed to the inclusion of offstream fish hatcheries, the use of different crop coefficients to estimate irrigation, and the availability of more detailed information in the 1990 estimates. Surface-water withdrawals accounted for 92 percent of the total withdrawals in 1990; irrigation was the largest category of water use, accounting for 82 percent of the total withdrawals.

Water-Resources Investigations Report↗
USGS2007

Relation Between Selected Water-Quality Variables, Climatic Factors, and Lake Levels in Upper Klamath and Agency Lakes, Oregon, 1990-2006

Growth and decomposition of dense blooms of Aphanizomenon flos-aquae in Upper Klamath Lake frequently cause extreme water-quality conditions that have led to critical fishery concerns for the region, including the listing of two species of endemic suckers as endangered. The Bureau of Reclamation has asked the U.S. Geological Survey (USGS) to examine water-quality data collected by the Klamath Tribes for relations with lake level. This analysis evaluates a 17-year dataset (1990-2006) and updates a previous USGS analysis of a 5-year dataset (1990-94). Both univariate hypothesis testing and multivariable analyses evaluated using an information-theoretic approach revealed the same results-no one overarching factor emerged from the data. No single factor could be relegated from consideration either. The lack of statistically significant, strong correlations between water-quality conditions, lake level, and climatic factors does not necessarily show that these factors do not influence water-quality conditions; it is more likely that these conditions work in conjunction with each other to affect water quality. A few different conclusions could be drawn from the larger dataset than from the smaller dataset examined in 1996, but for the most part, the outcome was the same. Using an observational dataset that may not capture all variation in water-quality conditions (samples were collected on a two-week interval) and that has a limited range of conditions for evaluation (confined to the operation of lake) may have confounded the exploration of explanatory factors. In the end, all years experienced some variation in poor water-quality conditions, either in timing of occurrence of the poor conditions or in their duration. The dataset of 17 years simply provided 17 different patterns of lake level, cumulative degree-days, timing of the bloom onset, and poor water-quality conditions, with no overriding causal factor emerging from the variations. Water-quality conditions were evaluated for their potential to be harmful to the endangered sucker species on the basis of high-stress thresholds-water temperature values greater than 28 degrees Celsius, dissolved-oxygen concentrations less than 4 milligrams per liter, and pH values greater than 9.7. Few water temperatures were greater than 28 degrees Celsius, and dissolved-oxygen concentrations less than 4 milligrams per liter generally were recorded in mid to late summer. In contrast, high pH values were more frequent, occurring earlier in the season and parallel with growth in the algal bloom. The 10 hypotheses relating water-quality variables, lake level, and climatic factors from the earlier USGS study were tested in this analysis for the larger 1990-2006 dataset. These hypotheses proposed relations between lake level and chlorophyll-a, pH, dissolved oxygen, total phosphorus, and water temperature. As in the previous study, no evidence was found in the larger dataset for any of these relations based on a seasonal (May-October) distribution. When analyzing only the June data, the previous 5-year study did find evidence for three hypotheses relating lake level to the onset of the bloom, chlorophyll-a concentrations, and the frequency of high pH values in June. These hypotheses were not supported by the 1990-2006 dataset, but the two hypotheses related to cumulative degree-days from the previous study were: chlorophyll-a concentrations were lower and onset of the algal bloom was delayed when spring air temperatures were cooler. Other relations between water-quality variables and cumulative degree-days were not significant. In an attempt to identify interrelations among variables not detected by univariate analysis, multiple regressions were performed between lakewide measures of low dissolved-oxygen concentrations or high pH values in July and August and six physical and biological variables (peak chlorophyll-a concentrations, degree-days, water temperature, median October-May discharg

Scientific Investigations Report↗
USGS2014

Hydrothermal monitoring in a quiescent volcanic arc: Cascade Range, northwestern United States

Ongoing (1996–present) volcanic unrest near South Sister, Oregon, is accompanied by a striking set of hydrothermal anomalies, including elevated temperatures, elevated major ion concentrations, and 3 He/ 4 He ratios as large as 8.6 R A in slightly thermal springs. These observations prompted the US Geological Survey to begin a systematic hydrothermal-monitoring effort encompassing 25 sites and 10 of the highest-risk volcanoes in the Cascade volcanic arc, from Mount Baker near the Canadian border to Lassen Peak in northern California. A concerted effort was made to develop hourly, multiyear records of temperature and/or hydrothermal solute flux, suitable for retrospective comparison with other continuous geophysical monitoring data. Targets included summit fumarole groups and springs/streams that show clear evidence of magmatic influence in the form of high 3 He/ 4 He ratios and/or anomalous fluxes of magmatic CO 2 or heat. As of 2009–2012, summit fumarole temperatures in the Cascade Range were generally near or below the local pure water boiling point; the maximum observed superheat was <2.5°C at Mount Baker. Variability in ground temperature records from the summit fumarole sites is temperature-dependent, with the hottest sites tending to show less variability. Seasonal variability in the hydrothermal solute flux from magmatically influenced springs varied from essentially undetectable to a factor of 5–10. This range of observed behavior owes mainly to the local climate regime, with strongly snowmelt-influenced springs and streams exhibiting more variability. As of the end of the 2012 field season, there had been 87 occurrences of local seismic energy densities approximately ≥ 0.001 J/m 3 during periods of hourly record. Hydrothermal responses to these small seismic stimuli were generally undetectable or ambiguous. Evaluation of multiyear to multidecadal trends indicates that whereas the hydrothermal system at Mount St. Helens is still fast-evolving in response to the 1980–present eruptive cycle, there is no clear evidence of ongoing long-term trends in hydrothermal activity at other Cascade Range volcanoes that have been active or restless during the past century (Baker, South Sister, and Lassen). Experience gained during the Cascade Range hydrothermal-monitoring experiment informs ongoing efforts to capture entire unrest cycles at more active but generally less accessible volcanoes such as those in the Aleutian arc.

California;Oregon;Washington↗
USGS2015

Depth-to-basement, sediment-thickness, and bathymetry data for the deep-sea basins offshore of Washington, Oregon, and California

Contours and derivative raster files of depth-to-basement, sediment-thickness, and bathymetry data for the area offshore of Washington, Oregon, and California are provided here as GIS-ready shapefiles and GeoTIFF files. The data were used to generate paper maps in 1992 and 1993 from 1984 surveys of the U.S. Exclusive Economic Zone by the U.S. Geological Survey for depth to basement and sediment thickness, and from older data for the bathymetry.

California, Oregon, Washington↗
USGS1937

Thermal springs in the United States

The earliest extensive studies of thermal springs in the United States were made by physicians. In 1831 Dr. John Bell issued a book entitled "Baths and Mineral Waters" in which he listed 21 spring localities. In the edition of his work published in 1855 the number was increased to 181. The earliest report on a geologic study of thermal springs was that of W. B, Rogers in 1840 on the thermal springs of Virginia. In 1875 G. K. Gilbert published a map and table showing thermal springs in the United States and pointed out that they are present chiefly in the mountainous areas of folded and faulted rocks. Early geologic study of them was principally inspired by the information which they afford at a few places on the deposition of minerals. The relation of hot springs to volcanic action has been studied in the Yellowstone National Park and near Lassen Peak in California. Studies in recent years have been concerned with the source of the water as well as of its heat. All the notable thermal springs in the eastern United States are in the Appalachian Highlands, principally in the region of folded rocks. The Atlantic Coastal Plain contains no appreciably warm springs. In Florida there are large springs whose water rises from a depth of a few hundred feet and is about 5° above the mean annual temperature, but they are not usually classed as thermal. The only warm springs in the great Interior Plains region are at and near Hot Springs, S. Dak., in the vicinity of the Black Hills uplift of crystalline rocks. In the Interior Highlands thermal springs occur only in the Ozark region, the largest group being at Hot Springs, Ark. The Rocky Mountain System includes the Yellowstone National Park, with its world-famous hot springs and geysers (see pis. 7,12), and there are many other hot springs within this great mountainous region. In the Intermontane areas of great lava plains and faulted lava mountains in Utah, Nevada, southern Idaho, and eastern Oregon there are many hot springs, closely associated with the larger faults. In the Pacific Mountain System, including the Cascade Range and Sierra Nevada, there are many warm and hot springs, some of which issue in areas of granite, and others in areas of lava. In the Coast Ranges of California many thermal springs issue from different geologic formations. Of the total of more than 1,000 thermal-spring localities listed in this paper more than half are situated in the three States of Idaho, California, and Nevada, each of which contains more than 150 thermal-spring localities. Wyoming, including the Yellowstone National Park, contains more than 100 hot-spring localities. Oregon, Utah, Colorado, Montana, and New Mexico contain several dozen thermal springs each, of which the principal ones are developed as resorts. The other thermal springs are scattered through 12 States, of which Massachusetts, New York, Pennsylvania, and North Carolina contain one spring or group each. More than half of the total number are developed as resorts or used for irrigation or water supply, but many have remained undeveloped because they are not easily accessible.

Water Supply Paper↗
USGS2013

Development of CE-QUAL-W2 models for the Middle Fork Willamette and South Santiam Rivers, Oregon

Hydrodynamic (CE-QUAL-W2) models of Hills Creek Lake (HCL), Lookout Point Lake (LOP), and Dexter Lake (DEX) on the Middle Fork Willamette River (MFWR), and models of Green Peter Lake and Foster Lake on the South Santiam River systems in western Oregon were updated and recalibrated for a wide range of flow and meteorological conditions. These CE-QUAL-W2 models originally were developed by West Consultants, Inc., for the U.S. Army Corps of Engineers. This study by the U.S. Geological Survey included a reassessment of the models’ calibration in more recent years—2002, 2006, 2008, and 2011—categorized respectively as low, normal, high, and extremely high flow calendar years. These years incorporated current dam-operation practices and more available data than the time period used in the original calibration. Modeled water temperatures downstream of both HCL and LOP-DEX on the MFWR were within an average of 0.68 degree Celsius (°C) of measured values; modeled temperatures downstream of Foster Dam on the South Santiam River were within an average of 0.65°C of measured values. A new CE-QUAL-W2 model was developed and calibrated for the riverine MFWR reach between Hills Creek Dam and the head of LOP, allowing an evaluation of the flow and temperature conditions in the entire MFWR system from HCL to Dexter Dam. The complex bathymetry and long residence time of HCL, combined with the relatively deep location of the power and regulating outlet structures at Hills Creek Dam, led to a HCL model that was highly sensitive to several outlet and geometric parameters related to dam structures (STR TOP, STR BOT, STR WIDTH). Release temperatures from HCL were important and often persisted downstream as they were incorporated in the MFWR model and the LOP-DEX model (downstream of MFWR). The models tended to underpredict the measured temperature of water releases from Dexter Dam during the late-September-through-December drawdown period in 2002, and again (to a lesser extent) in 2011, but simulations were much more accurate in 2006 and 2008. This episodic model bias may have been a result of hot, dry conditions; lower lake elevations; and earlier drawdown at both HCL and LOP in 2002. These dry conditions in 2002 may have contradicted assumptions inherent in the estimation of certain model inputs, such as unmeasured inflows and water temperatures, which may respond differently during dry years than during normal and wet years. This report documents the development and calibration of new and revised flow and water-temperature models for riverine and reservoir reaches in the Middle Fork Willamette River and South Santiam River systems. Methods and model parameter values were established for the accurate simulation of flows and temperatures in these systems under current conditions. By extension, these models should be able to accurately simulate flows and temperatures under potential future conditions in which dam operations and dam outlet structures may be changed as part of a strategy to improve habitat, fish passage, and temperature conditions for endangered fish.

Oregon↗
USGS1999

Volcano hazards in the Mount Jefferson region, Oregon

Mount Jefferson is a prominent feature of the landscape seen from highways east and west of the Cascades. Mount Jefferson (one of thirteen major volcanic centers in the Cascade Range) has erupted repeatedly for hundreds of thousands of years, with its last eruptive episode during the last major glaciation which culminated about 15,000 years ago. Geologic evidence shows that Mount Jefferson is capable of large explosive eruptions. The largest such eruption occurred between 35,000 and 100,000 years ago, and caused ash to fall as far away as the present-day town of Arco in southeast Idaho. Although there has not been an eruption at Mount Jefferson for some time, experience at explosive volcanoes elsewhere suggests that Mount Jefferson cannot be regarded as extinct. If Mount Jefferson erupts again, areas close to the eruptive vent will be severely affected, and even areas tens of kilometers (tens of miles) downstream along river valleys or hundreds of kilometers (hundreds of miles) downwind may be at risk. Numerous small volcanoes occupy the area between Mount Jefferson and Mount Hood to the north, and between Mount Jefferson and the Three Sisters region to the south. These small volcanoes tend not to pose the far-reaching hazards associated with Mount Jefferson, but are nonetheless locally important. A concern at Mount Jefferson, but not at the smaller volcanoes, is the possibility that small to- moderate sized landslides could occur even during periods of no volcanic activity. Such landslides may transform as they move into lahars (watery flows of rock, mud, and debris) that can inundate areas far downstream. The population at immediate risk in the Mount Jefferson region is small, but these residents as well as other people who visit the area for recreation and work purposes should be aware of the potential hazards. Probably the greatest concern in the Mount Jefferson region is the possibility that large lahars might enter reservoirs on either side of the volcano, namely, Detroit Lake to the west and Lake Billy Chinook to the east. Lahars entering these lakes could set up large waves that could overtop dams and possibly cause dam failure, with catastrophic effects downstream. Such events have very low probabilities but great potential consequences. This report describes the kinds of hazardous geologic events that have occurred in the Mount Jefferson area in the past and shows, in the accompanying volcano-hazards-zonation maps, which areas will likely be at risk when hazardous events occur again in the future.

Oregon↗
USGS2010

Groundwater conditions during 2009 and changes in groundwater levels from 1984 to 2009, Columbia Plateau Regional Aquifer System, Washington, Oregon, and Idaho

Groundwater elevations in three basalt units and one unconsolidated hydrogeologic unit in the Columbia Plateau Regional Aquifer System were measured and evaluated to provide a regional overview of groundwater conditions in spring 2009. Water levels for the Saddle Mountains unit, the Wanapum unit, the Grande Ronde unit, and for the overlying Overburden unit were measured in 1,752 wells during spring 2009 by the U.S. Geological Survey (USGS) and 10 other Federal, State, Tribal, and local agencies, including 66 wells located and measured by the USGS specifically for this study. These data were analyzed to determine the presence of spatial correlation of groundwater levels with distance and direction from each other. Groundwater flow in the Palouse Slope structural region showed evidence of being more continuous relative to groundwater flow in the Yakima Fold Belt, where the geologic complexity may contribute to compartmentalization of groundwater flow. This information was used to interpolate the generalized groundwater elevations for each of the basalt hydrogeologic units and to provide information on regional flow. Water-level change maps were constructed for the three basalt hydrogeologic units and the Overburden (unconsolidated) unit. Groundwater levels measured in spring 1984 and 2009 in 470 wells were compared. Small to moderate groundwater-level declines were measured in most wells, although declines greater than 100 ft and as great as 300 ft were measured in many wells. Essentially unchanged groundwater levels were measured in other wells. Of the wells measured in 1984 and 2009, water levels declined in 83 percent of the wells, and declines greater than 25 ft were measured in 29 percent of all wells. The groundwater-level changes were greatest in the deeper hydrogeologic units. Mean groundwater-level changes ranged from a 7 ft decline for the Overburden unit to a 51 ft decline for the Grande Ronde unit. The average annual rates of groundwater-level change for the 25-year period ranged from a 0.3 ft/yr decline for the Overburden unit to a 2.0 ft/yr decline for the Grande Ronde unit. Groundwater level declines were identified throughout the Columbia Plateau, but areas with large and widespread declines were located in the central northern part of the study area, in parts of the Yakima River basin in Washington, in the Pullman-Moscow area in Washington and Idaho, and in parts of the Umatilla River basin in Oregon. These declines are in areas known to rely heavily on groundwater for irrigation and other uses.

Idaho, Oregon, Washington↗
USGS1981

1980 Water resources program in Oregon

The Water Resources Division investigates and reports on the occurrence, quantity, quality, distribution, and movement of surface and underground water. Work of the Division is described in detail later in this report.

Oregon↗
USGS2015

Sources and transport of phosphorus to rivers in California and adjacent states, U.S., as determined by SPARROW modeling

The SPARROW (SPAtially Referenced Regression on Watershed attributes) model was used to simulate annual phosphorus loads and concentrations in unmonitored stream reaches in California, U.S., and portions of Nevada and Oregon. The model was calibrated using de-trended streamflow and phosphorus concentration data at 80 locations. The model explained 91% of the variability in loads and 51% of the variability in yields for a base year of 2002. Point sources, geological background, and cultivated land were significant sources. Variables used to explain delivery of phosphorus from land to water were precipitation and soil clay content. Aquatic loss of phosphorus was significant in streams of all sizes, with the greatest decay predicted in small- and intermediate-sized streams. Geological sources, including volcanic rocks and shales, were the principal control on concentrations and loads in many regions. Some localized formations such as the Monterey shale of southern California are important sources of phosphorus and may contribute to elevated stream concentrations. Many of the larger point source facilities were located in downstream areas, near the ocean, and do not affect inland streams except for a few locations. Large areas of cultivated land result in phosphorus load increases, but do not necessarily increase the loads above those of geological background in some cases because of local hydrology, which limits the potential of phosphorus transport from land to streams.

Journal of the American Water Resources Associatio↗
USGS2020

Evaluation of restoration alternatives using water-budget tools for the Wapato Lake National Wildlife Refuge, northwestern Oregon

The lakebed in Wapato Lake National Wildlife Refuge (NWR) in northwestern Oregon was farmed for decades prior to the establishment of the refuge in 2013. Planning for restoration of these lands required extensive data collection and construction of a water budget and tools to design and evaluate potential restoration strategies. The U.S. Geological Survey (USGS) and U.S. Fish and Wildlife Service worked together to monitor streamflow and water levels in and around Wapato Lake NWR, apply the USGS Shoreline Management Tool (SMT), then construct and apply a water-budget-based Water Management Scenario Tool (WMST). The SMT was used to determine the spatial availability of different water depths (as potential habitat for different species) as a function of water level and other factors, based on topographic data. The WMST uses a water-budget approach to predict daily water levels, inflows, outflows, and areas of specific categories of water depth in the refuge over the course of a water year in response to a range of hydrologic and meteorological conditions and potential water-management strategies. In this study, two hypothetical water-management strategies were simulated to predict their effect on water levels and areas with specific water depths as an indicator of potential habitat. In the first scenario, several tributaries that had been diverted around the lakebed since the 1930s were reconnected to the lake, and an outflow weir was used to control lake level and to create a lake and seasonal wetlands of specific depths. In the second scenario, an outflow weir was combined with pumps to help meet target lake levels. Results showed that reconnecting the largest three tributaries to Wapato Lake would provide sufficient water to create a range of aquatic conditions in most years. For a median water year, rainfall and tributary flows in these scenarios provided 99 percent of total inputs to the lake, whereas pumping, weir outflows, and open-water evaporation accounted for 95–97 percent of losses. Management of lake levels could be accomplished with a variable-elevation outflow weir or a combination of a weir and pumps. The lake would take longer to fill to a higher seasonal target level during a dry year. Without an outflow weir or other means of allowing water to flow out of the lake, the largest of two existing pumps would need to be used during late spring or early summer to attain a lower seasonal target water level in summer. High-water conditions downstream of Wapato Lake may prevent the use of a simple outflow weir, as historical downstream water levels in winter and spring sometimes were higher than the target water levels used in these scenarios. Water-budget-based methods applied in this study have proven to be valuable for the design and evaluation of potential restoration strategies at Wapato Lake NWR.

Wapato Lake National Wildlife Refuge↗