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• 661. [Article] Potential for dispersal of the non-native parasite Myxobolus cerebralis : qualitative risk assessments for the state of Alaska and the Willamette River Basin, Oregon

  First introduced to the USA in 1958, Myxobolus cerebralis, the parasite responsible for whirling disease in salmonids, has since spread across the country causing severe declines in wild trout populations ...

  Citation × Citation Citation Abstract Copy Title: Potential for dispersal of the non-native parasite Myxobolus cerebralis : qualitative risk assessments for the state of Alaska and the Willamette River Basin, Oregon Author: Arsan, E. Leyla First introduced to the USA in 1958, Myxobolus cerebralis, the parasite responsible for whirling disease in salmonids, has since spread across the country causing severe declines in wild trout populations in the intermountain west. Recent development of risk assessment models used to assess the likelihood and consequences of exotic parasite introduction, have strengthened the process of science-based decision-making in aquatic animal health. In the case of M. cerebralis, it is necessary to use a risk assessment model with two unique segments that clearly address the distinct life stages and respective hosts of the parasite separately. The studies described examine the probability of M. cerebralis introduction and establishment for two regions: the state of Alaska, and the Willamette River basin, Oregon. The Alaska risk assessment was based on the assumption that the parasite did not already occur in the state. However, in the process of validating this assumption, we documented the first polymerase chain reaction (PCR) detection of the parasite in the state. The pathogen was identified in hatchery rainbow trout (Oncorhynchus mykiss) from the Anchorage area. Although this is the first detection of the parasite in Alaska, clinical whirling disease has never been documented in the state. To qualitatively assess the risk of further spread of M. cerebralis in Alaska, four potential routes of dissemination were examined: movement of fish by humans, natural dispersal (via migratory birds and stray anadromous salmon), recreational activities, and commercial seafood processing. This research indicates the most likely pathway for M. cerebralis transport in Alaska is human movement of fish. In the Willamette River basin, Oregon, introduction of M. cerebralis has already occurred, though establishment appears limited to a single private hatchery. Introduction in this region was considered the most likely to occur as a result of human movements of fish. Straying anadromous salmonids were also assessed and were present in higher numbers than predicted. However, they were not infected with the parasite, and thus the probability for introduction by this route is low. The probability of introduction of the parasite varies throughout the Willamette River basin. Areas with the highest probability for M. cerebralis introduction were identified as the Clackamas and Santiam River subbasins. The Clackamas River has already experienced an introduction of the parasite, has the largest concentration of hatcheries (state, federal, and private), has a popular sport fishery, and is the closest major tributary to the enormous piscivorous bird-populations in the Columbia River estuary. The Santiam subbasin has a popular sport fishery, received the highest number of stray fish in the Willamette River basin, and has the second largest concentration of hatcheries in the Willamette River basin. Unique from introduction, establishment of the parasite is dependent upon several environmental and biological factors including: water temperatures, spatial/temporal overlap of hosts, and the distribution and genetic composition of the parasite’s invertebrate host, Tubifex tubifex. The distribution, genetic composition and susceptibility of T. tubifex, were considered the most important factor in the ability of M. cerebralis to establish in both systems. Surveys of oligochaete populations were conducted in both study regions. In Alaska, T. tubifex was not detected from the southeast region and the apparent lack of appropriate tubificid hosts may prevent establishment in that part of the state. However, 4 lineages (I, III, IV, and VI) of the species were identified from southcentral Alaska. Lineage IV has not been previously been described in North America and its susceptibility to M. cerebralis was unknown. When lineage IV T. tubifex and 3 mixed-lineage (I, III, IV and VI) groups were exposed to M. cerebralis, only lineage III became infected under our experimental conditions. Thus, if the parasite were dispersed, conditions are appropriate for establishment and propagation of the parasite life cycle in southcentral Alaska, although detrimental effects on fish populations may be reduced as a result of the presence of non-susceptible lineages of T. tubifex. The probability of further establishment in this area is greatest in Ship Creek, where the abundance of susceptible T. tubifex, the presence of susceptible rainbow trout (Oncorhynchus mykiss), and the proximity to the known area of infection make conditions particularly appropriate. Similar to findings in Alaska, the Willamette River basin, Oregon also supports populations of susceptible T. tubifex. If the pathogen were introduced, probability of establishment is high in certain areas of the basin as all conditions are appropriate for propagation of the parasite life cycle. Tributaries to the mainstem Willamette River have the highest probability of establishment as these areas have the greatest numbers of susceptible T. tubifex. However, the abundance of resistant strains of T. tubifex could mitigate the effects of M. cerebralis if introduced. Management recommendations to reduce the likelihood of parasite dissemination are similar for Oregon and Alaska since human movement of fish and angler activities were considered the most likely routes of introduction for both regions. Based on this research, steps should also be taken to limit human movement of fish, whether by restricting carcass planting for stream enrichment in Oregon, or by prohibiting use of fish heads as bait in southcentral Alaska. The states should also allot resources to angler education and awareness of the effects of angler activity and recreation on dispersal of M. cerebralis. This could be done using a combination of brochures and signage at boat ramps describing how to prevent spread of aquatic nuisance species. Title: Potential for dispersal of the non-native parasite Myxobolus cerebralis : qualitative risk assessments for the state of Alaska and the Willamette River Basin, Oregon Author: Arsan, E. Leyla First introduced to the USA in 1958, Myxobolus cerebralis, the parasite responsible for whirling disease in salmonids, has since spread across the country causing severe declines in wild trout populations in the intermountain west. Recent development of risk assessment models used to assess the likelihood and consequences of exotic parasite introduction, have strengthened the process of science-based decision-making in aquatic animal health. In the case of M. cerebralis, it is necessary to use a risk assessment model with two unique segments that clearly address the distinct life stages and respective hosts of the parasite separately. The studies described examine the probability of M. cerebralis introduction and establishment for two regions: the state of Alaska, and the Willamette River basin, Oregon. The Alaska risk assessment was based on the assumption that the parasite did not already occur in the state. However, in the process of validating this assumption, we documented the first polymerase chain reaction (PCR) detection of the parasite in the state. The pathogen was identified in hatchery rainbow trout (Oncorhynchus mykiss) from the Anchorage area. Although this is the first detection of the parasite in Alaska, clinical whirling disease has never been documented in the state. To qualitatively assess the risk of further spread of M. cerebralis in Alaska, four potential routes of dissemination were examined: movement of fish by humans, natural dispersal (via migratory birds and stray anadromous salmon), recreational activities, and commercial seafood processing. This research indicates the most likely pathway for M. cerebralis transport in Alaska is human movement of fish. In the Willamette River basin, Oregon, introduction of M. cerebralis has already occurred, though establishment appears limited to a single private hatchery. Introduction in this region was considered the most likely to occur as a result of human movements of fish. Straying anadromous salmonids were also assessed and were present in higher numbers than predicted. However, they were not infected with the parasite, and thus the probability for introduction by this route is low. The probability of introduction of the parasite varies throughout the Willamette River basin. Areas with the highest probability for M. cerebralis introduction were identified as the Clackamas and Santiam River subbasins. The Clackamas River has already experienced an introduction of the parasite, has the largest concentration of hatcheries (state, federal, and private), has a popular sport fishery, and is the closest major tributary to the enormous piscivorous bird-populations in the Columbia River estuary. The Santiam subbasin has a popular sport fishery, received the highest number of stray fish in the Willamette River basin, and has the second largest concentration of hatcheries in the Willamette River basin. Unique from introduction, establishment of the parasite is dependent upon several environmental and biological factors including: water temperatures, spatial/temporal overlap of hosts, and the distribution and genetic composition of the parasite’s invertebrate host, Tubifex tubifex. The distribution, genetic composition and susceptibility of T. tubifex, were considered the most important factor in the ability of M. cerebralis to establish in both systems. Surveys of oligochaete populations were conducted in both study regions. In Alaska, T. tubifex was not detected from the southeast region and the apparent lack of appropriate tubificid hosts may prevent establishment in that part of the state. However, 4 lineages (I, III, IV, and VI) of the species were identified from southcentral Alaska. Lineage IV has not been previously been described in North America and its susceptibility to M. cerebralis was unknown. When lineage IV T. tubifex and 3 mixed-lineage (I, III, IV and VI) groups were exposed to M. cerebralis, only lineage III became infected under our experimental conditions. Thus, if the parasite were dispersed, conditions are appropriate for establishment and propagation of the parasite life cycle in southcentral Alaska, although detrimental effects on fish populations may be reduced as a result of the presence of non-susceptible lineages of T. tubifex. The probability of further establishment in this area is greatest in Ship Creek, where the abundance of susceptible T. tubifex, the presence of susceptible rainbow trout (Oncorhynchus mykiss), and the proximity to the known area of infection make conditions particularly appropriate. Similar to findings in Alaska, the Willamette River basin, Oregon also supports populations of susceptible T. tubifex. If the pathogen were introduced, probability of establishment is high in certain areas of the basin as all conditions are appropriate for propagation of the parasite life cycle. Tributaries to the mainstem Willamette River have the highest probability of establishment as these areas have the greatest numbers of susceptible T. tubifex. However, the abundance of resistant strains of T. tubifex could mitigate the effects of M. cerebralis if introduced. Management recommendations to reduce the likelihood of parasite dissemination are similar for Oregon and Alaska since human movement of fish and angler activities were considered the most likely routes of introduction for both regions. Based on this research, steps should also be taken to limit human movement of fish, whether by restricting carcass planting for stream enrichment in Oregon, or by prohibiting use of fish heads as bait in southcentral Alaska. The states should also allot resources to angler education and awareness of the effects of angler activity and recreation on dispersal of M. cerebralis. This could be done using a combination of brochures and signage at boat ramps describing how to prevent spread of aquatic nuisance species. Close

• 662. [Image] A review of the taxonomic status of pines including true firs within the pinus ponderosa forest in the southern portion of Crater Lake National Park, Oregon

  	ill.; Report title; "A report to the Superintendent, Crater Lake National Park, March 1982." - T.p.; Includes bibliographical references (p. 11-16)
  	Citation × Citation Citation Abstract Copy Title: A review of the taxonomic status of pines including true firs within the pinus ponderosa forest in the southern portion of Crater Lake National Park, Oregon Author: Mastrogiuseppe, R. J. Year: 1982, 2009 ill.; Report title; "A report to the Superintendent, Crater Lake National Park, March 1982." - T.p.; Includes bibliographical references (p. 11-16) Title: A review of the taxonomic status of pines including true firs within the pinus ponderosa forest in the southern portion of Crater Lake National Park, Oregon Author: Mastrogiuseppe, R. J. Year: 1982, 2009 ill.; Report title; "A report to the Superintendent, Crater Lake National Park, March 1982." - T.p.; Includes bibliographical references (p. 11-16) Close

• 663. [Article] Beyond the Angle of Repose: A Review and Synthesis of Landslide Processes in Response to Rapid Uplift, Eel River, Northern Eel River, Northern California

  In mountainous settings, increases in rock uplift are often followed by a commensurate uptick in denudation as rivers incise and steepen hillslopes, making them increasingly prone to landsliding as slope ...

  Citation × Citation Citation Abstract Copy Title: Beyond the Angle of Repose: A Review and Synthesis of Landslide Processes in Response to Rapid Uplift, Eel River, Northern Eel River, Northern California Author: Roering, Joshua J., Mackey, Benjamin H., Handwerger, Alexander L., Booth, Adam M., Schmidt, David A., Bennett, Georgina L., Cerovski-Darriau, Corina Year: 2015 In mountainous settings, increases in rock uplift are often followed by a commensurate uptick in denudation as rivers incise and steepen hillslopes, making them increasingly prone to landsliding as slope angles approach a limiting value. For decades, the threshold slope model has been invoked to account for landslide-driven increases in sediment flux that limit topographic relief, but the manner by which slope failures organize themselves spatially and temporally in order for erosion to keep pace with rock uplift has not been well documented. Here, we review past work and present new findings from remote sensing, cosmogenic adionuclides, suspended sediment records, and airborne lidar data, to decipher patterns of landslide activity and geomorphic processes related to rapid uplift along the northward-migrating Mendocino Triple Junction in Northern California. From historical air photos and airborne lidar, we estimated the velocity and sediment flux associated with active, slow-moving landslides (or earthflows) in the mélange- and argillite-dominated Eel River watershed using the downslope displacement of surface markers such as trees and shrubs. Although active landslides that directly convey sediment into the channel network account for only 7% of the landscape surface, their sediment flux amounts to more than 50% of the suspended load recorded at downstream sediment gauging stations. These active slides tend to exhibit seasonal variations in velocity as satellite-based interferometry has demonstrated that rapid acceleration commences within 1 to 2 months of the onset of autumn rainfall events before slower deceleration ensues in the spring and summer months. Curiously, this seasonal velocity pattern does not appear to vary with landslide size, suggesting that complex hydrologic-mechanical feedbacks (rather than 1-D pore pressure diffusion) may govern slide dynamics. A new analysis of 14 years of discharge and sediment concentration data for the Eel River indicates that the characteristic mid-winter timing of earthflow acceleration corresponds with increased suspended concentration values, suggesting that the seasonal onset of landslide motion each year may be reflected in the export of sediments to the continental margin. The vast majority of active slides exhibit gullied surfaces and the gully networks, which are also seasonally active, may facilitate sediment export although the proportion of material produced by this pathway is poorly known. Along Kekawaka Creek, a prominent tributary to the Eel River, new analyses of catchment-averaged erosion rates derived from cosmogenic radionuclides reveal rapid erosion (0.76 mm/yr) below a prominent knickpoint and slower erosion (0.29 mm/yr) upstream. Such knickpoints are frequently observed in Eel tributaries and are usually comprised of massive (>10m) interlocking resistant boulders that likely persist in the landscape for long time periods (>105yr). Upstream of these knickpoints, active landslides tend to be less frequent and average slope angles are slightly gentler than in downstream areas, which indicates that landslide density and average slope angle appear to increase with erosion rate. Lastly, we synthesize evidence for the role of large, catastrophic landslides in regulating sediment flux and landscape form. The emergence of resistant blocks within the mélange bedrock has promoted large catastrophic slides that have dammed the Eel River and perhaps generated outburst events in the past. The frequency and impact of these landslide dams likely depend on the spatial and size distributions of resistant blocks relative to the width and drainage area of adjacent valley networks. Overall, our findings demonstrate that landslides within the Eel River catchment do not occur randomly, but instead exhibit spatial and temporal patterns related to baselevel lowering, climate forcing, and lithologic variations. Combined with recent landscape evolution models that incorporate landslides, these results provide predictive capability for estimating erosion rates and managing hazards in mountainous regions. Title: Beyond the Angle of Repose: A Review and Synthesis of Landslide Processes in Response to Rapid Uplift, Eel River, Northern Eel River, Northern California Author: Roering, Joshua J., Mackey, Benjamin H., Handwerger, Alexander L., Booth, Adam M., Schmidt, David A., Bennett, Georgina L., Cerovski-Darriau, Corina Year: 2015 In mountainous settings, increases in rock uplift are often followed by a commensurate uptick in denudation as rivers incise and steepen hillslopes, making them increasingly prone to landsliding as slope angles approach a limiting value. For decades, the threshold slope model has been invoked to account for landslide-driven increases in sediment flux that limit topographic relief, but the manner by which slope failures organize themselves spatially and temporally in order for erosion to keep pace with rock uplift has not been well documented. Here, we review past work and present new findings from remote sensing, cosmogenic adionuclides, suspended sediment records, and airborne lidar data, to decipher patterns of landslide activity and geomorphic processes related to rapid uplift along the northward-migrating Mendocino Triple Junction in Northern California. From historical air photos and airborne lidar, we estimated the velocity and sediment flux associated with active, slow-moving landslides (or earthflows) in the mélange- and argillite-dominated Eel River watershed using the downslope displacement of surface markers such as trees and shrubs. Although active landslides that directly convey sediment into the channel network account for only 7% of the landscape surface, their sediment flux amounts to more than 50% of the suspended load recorded at downstream sediment gauging stations. These active slides tend to exhibit seasonal variations in velocity as satellite-based interferometry has demonstrated that rapid acceleration commences within 1 to 2 months of the onset of autumn rainfall events before slower deceleration ensues in the spring and summer months. Curiously, this seasonal velocity pattern does not appear to vary with landslide size, suggesting that complex hydrologic-mechanical feedbacks (rather than 1-D pore pressure diffusion) may govern slide dynamics. A new analysis of 14 years of discharge and sediment concentration data for the Eel River indicates that the characteristic mid-winter timing of earthflow acceleration corresponds with increased suspended concentration values, suggesting that the seasonal onset of landslide motion each year may be reflected in the export of sediments to the continental margin. The vast majority of active slides exhibit gullied surfaces and the gully networks, which are also seasonally active, may facilitate sediment export although the proportion of material produced by this pathway is poorly known. Along Kekawaka Creek, a prominent tributary to the Eel River, new analyses of catchment-averaged erosion rates derived from cosmogenic radionuclides reveal rapid erosion (0.76 mm/yr) below a prominent knickpoint and slower erosion (0.29 mm/yr) upstream. Such knickpoints are frequently observed in Eel tributaries and are usually comprised of massive (>10m) interlocking resistant boulders that likely persist in the landscape for long time periods (>105yr). Upstream of these knickpoints, active landslides tend to be less frequent and average slope angles are slightly gentler than in downstream areas, which indicates that landslide density and average slope angle appear to increase with erosion rate. Lastly, we synthesize evidence for the role of large, catastrophic landslides in regulating sediment flux and landscape form. The emergence of resistant blocks within the mélange bedrock has promoted large catastrophic slides that have dammed the Eel River and perhaps generated outburst events in the past. The frequency and impact of these landslide dams likely depend on the spatial and size distributions of resistant blocks relative to the width and drainage area of adjacent valley networks. Overall, our findings demonstrate that landslides within the Eel River catchment do not occur randomly, but instead exhibit spatial and temporal patterns related to baselevel lowering, climate forcing, and lithologic variations. Combined with recent landscape evolution models that incorporate landslides, these results provide predictive capability for estimating erosion rates and managing hazards in mountainous regions. Close

• 664. [Image] Lakeview proposed resource management plan and final environmental impact statement [volume 3]

  	4 v.; maps (some col.); "August 2002"; "January 2003" -- cover
  	Citation × Citation Citation Abstract Copy Title: Lakeview proposed resource management plan and final environmental impact statement [volume 3] Author: U.S. Department of the Interior. Bureau of Land Management; Lakeview Resource Area Office. Lakeview District Year: 2002, 2008, 2006 4 v.; maps (some col.); "August 2002"; "January 2003" -- cover Title: Lakeview proposed resource management plan and final environmental impact statement [volume 3] Author: U.S. Department of the Interior. Bureau of Land Management; Lakeview Resource Area Office. Lakeview District Year: 2002, 2008, 2006 4 v.; maps (some col.); "August 2002"; "January 2003" -- cover Close

• 665. [Image] Final biological assessment: the effects of proposed actions related to Klamath Project operation (April 1, 2002-March 31, 2012) on federally-listed threatened and endangered species

  	"Partially incorporating January 22, 2001 Biological assessment submitted to the National Marine Fisheries Service and February 13, 2001 Biological Assessment submitted to the U.S. Fish and Wildlife Service" ...
  	Citation × Citation Citation Abstract Copy Title: Final biological assessment: the effects of proposed actions related to Klamath Project operation (April 1, 2002-March 31, 2012) on federally-listed threatened and endangered species Author: United States. Bureau of Reclamation. Klamath Basin Area Office Year: 2002, 2004 "Partially incorporating January 22, 2001 Biological assessment submitted to the National Marine Fisheries Service and February 13, 2001 Biological Assessment submitted to the U.S. Fish and Wildlife Service" ; Includes bibliographical references ; "February 25, 2002" Title: Final biological assessment: the effects of proposed actions related to Klamath Project operation (April 1, 2002-March 31, 2012) on federally-listed threatened and endangered species Author: United States. Bureau of Reclamation. Klamath Basin Area Office Year: 2002, 2004 "Partially incorporating January 22, 2001 Biological assessment submitted to the National Marine Fisheries Service and February 13, 2001 Biological Assessment submitted to the U.S. Fish and Wildlife Service" ; Includes bibliographical references ; "February 25, 2002" Close

• 666. [Image] Klamath Falls Resource Area resource management plan and environmental impact statement : final : Volume 1

  	Proposed resource management plan/final environmental impact statement for the Klamath Falls Resource Area
  	Citation × Citation Citation Abstract Copy Title: Klamath Falls Resource Area resource management plan and environmental impact statement : final : Volume 1 Author: United States. Bureau of Land Management. Klamath Falls Resource Area Office Year: 1994, 2005, 2004 Proposed resource management plan/final environmental impact statement for the Klamath Falls Resource Area Title: Klamath Falls Resource Area resource management plan and environmental impact statement : final : Volume 1 Author: United States. Bureau of Land Management. Klamath Falls Resource Area Office Year: 1994, 2005, 2004 Proposed resource management plan/final environmental impact statement for the Klamath Falls Resource Area Close

• 667. [Image] Review of the hatchery measures in the Oregon plan for salmon and watersheds. Part I, Consistency of the Oregon plan with recommendations from recent scientific review panels

  	"December 10, 1998."
  	Citation × Citation Citation Abstract Copy Title: Review of the hatchery measures in the Oregon plan for salmon and watersheds. Part I, Consistency of the Oregon plan with recommendations from recent scientific review panels Author: Independent Multidisciplinary Science Team (Or.) Year: 1998, 2005 "December 10, 1998." Title: Review of the hatchery measures in the Oregon plan for salmon and watersheds. Part I, Consistency of the Oregon plan with recommendations from recent scientific review panels Author: Independent Multidisciplinary Science Team (Or.) Year: 1998, 2005 "December 10, 1998." Close

• 668. [Image] Water availability for Oregon's rivers and streams: Volume 2; Technical guide and appendixes

  	Title from cover; "May 1991"
  	Citation × Citation Citation Abstract Copy Title: Water availability for Oregon's rivers and streams: Volume 2; Technical guide and appendixes Author: Robison, E. George Year: 1991, 2004 Title from cover; "May 1991" Title: Water availability for Oregon's rivers and streams: Volume 2; Technical guide and appendixes Author: Robison, E. George Year: 1991, 2004 Title from cover; "May 1991" Close

• 669. [Image] Draft upper Klamath River management plan environmental impact statement and resource management plan amendments. Volume 2 - Appendices

  	"BLM/OR/WA/PL-02/038+1792"--P. [2] of cover; Cover title; Includes bibliographical references (v. 2, p. 219-228) and index
  	Citation × Citation Citation Abstract Copy Title: Draft upper Klamath River management plan environmental impact statement and resource management plan amendments. Volume 2 - Appendices Author: United States. Bureau of Land Management. Klamath Falls Resource Area Office Year: 2003, 2004 "BLM/OR/WA/PL-02/038+1792"--P. [2] of cover; Cover title; Includes bibliographical references (v. 2, p. 219-228) and index Title: Draft upper Klamath River management plan environmental impact statement and resource management plan amendments. Volume 2 - Appendices Author: United States. Bureau of Land Management. Klamath Falls Resource Area Office Year: 2003, 2004 "BLM/OR/WA/PL-02/038+1792"--P. [2] of cover; Cover title; Includes bibliographical references (v. 2, p. 219-228) and index Close

• 670. [Image] Preliminary report on the ground-water resources of the Klamath River Basin, Oregon

  	The Klamath River basin, including the adjacent Lost River basin, includes about ?,5>OO square miles of plateaus, mountain-slopes and valley plains in south-central Oregon* The valley plains range in altitude ...
  	Citation × Citation Citation Abstract Copy Title: Preliminary report on the ground-water resources of the Klamath River Basin, Oregon Author: Newcomb, Reuben Clair Year: 1958, 2005 The Klamath River basin, including the adjacent Lost River basin, includes about ?,5>OO square miles of plateaus, mountain-slopes and valley plains in south-central Oregon* The valley plains range in altitude from about U,100 feet in the south to more than li,500 feet at the northern end; the mountain and plateau lands rise to an average altitude of 6,000 feet at the drainage divide, some peaks rising above 9*000 feet. The western quarter of the ba3in is on the eastern slope of the Cascade Range and the remainder consists of plateaus, mountains, and valleys of the basin-and-range type* The rocks of the Klamath River basin range in age from Recent to Mesozoic* At the southwest side of the basin in Oregon, pre~Tertiary metamorphic, igneous, and sedimentary rocks, which form extensive areas farther west, are overlain by sedimentary rocks of Eocene age and volcanic rocks of Eocene and Oligocene age* These early Tertiary rocks dip east toward the central part of the Klamath River basin. The complex "volcanic rocks of high Cascades" include three units: The lowest unit consists of a sequence of basaltic lava flows about 800 feet thick5 the medial unit is composed of volcanic-sedimentary and sedimentary rocks?the Tonna formation-200 to 2,000 feet thick; the uppermost unit is a sequence of basaltic lava flows commonly about 200 feet thick. These rocks dip east from the Cascade Unpublished records subject to revision 2 Range and are the main bedrock formations beneath most of the basin. Extensive pumice deposits, which emanated ^?^ ancestral Mount Mazaraa, cover large areas in the northwestern part of the basin* The basin has an overall synclinal structure open to the south at the California boundary where it continues as the Klamath Lake basin in California* The older rocks dip into the basin in monoclinal fashion from the adjoining drainage basins* The rocks are broken along rudely rectangular nets of closely spaced normal faults* the most prominent set of which trends northwest* The network of fault displacements includes two main grabens, the Klamath and the Langell, which were downthrown approximately ?00 and 1,000 fast, respectively* The average annual precipitation varies with the altitude, the higher parts of the Cascade Range getting more than 60 inches, and the semierid valley plains receive as little as 13 inches in some places* Most precipitation occurs in the winter. \ The principal tributaries, Williamson and Sprague Rivers, rise near the higher parts of the eastern rim of the basin, flow through narrow valley plains to the western part, and discharge into Upper Klamath Lake* Wood River and associated creeks also empty into Upper Klamath Lake after draining southward along the eastern foot of the Cascade Range* The Klamath River receives the outflow from Upper Klamath Lake, via Lifak River and Lake Ewauna, and flows southwestward through Keno Gap and hence through a youthful canyon, to its lower valley in California* The ground water occurs largely in an unconfined, or water-table, condition, though areas of local confinement are present* The regional Unpublished records subject to revis&oa is graded to water table / a base level about equal to that of the major drainage* where water is confined, on the valley plains. The slope of the water tafele, ~ of/the piezomstric surface is downstream at about the same grade as that "of the surface drainage in each of the larger valleys, attd groufid*water divides occur between the upper parts of adjacent major valleys* The principal water-bearipg units are.the'lower lava rocks and upper lava rocks of the "volcanic rocks of high Cascades,* the pumice of Quaternaryage, and the allusriTuju In places layers of coarse flagmental material in the Tonna formation (Newcorub, 1958) also transmit water* The water-bearing units, especially the breccia layers of the lava rocks and the pumice, yield large amounts of water to wells and provide natural discharge outlets for the ground water. The spring outflows to the Williamson and Wood Rivers-Crooked Creek drainage, measured in September and October 1955, were at a rate equivalent to about 700,000 acre-feet per year. The spring outflows into the Sprague River were at a rate equal to 2l;5>000 apre-feet per year* Large springs occur along the edges of Upper Klamath Lake but their discharges could not be measured, and the known spring discharge from the lower lava rocks in the river canyon below Keno was not measured. The spring discharge into Lost River in the reach ?rom Bonanza to Harpold Bridge was at a rate equivalent to 75,000 acre-feet per year. Much of the water discharged from springs is used for irrigation during the growing season, but ground water has not been extensively Unpublished records subject to revision developed by means of wells except in the'Yonna Valley and other local areas. The total withdrawal of ground water from wells in 1951? was only about 30,000 acre-feet, of which 27,000 was used for irrigation* The ground water is of excellent quality in general, but sodium sulfate water occurs in the belts of warm rock along some faults and alkali bicarbonate water is present in the main evapotranspiration basins. Unpublished records subject to revision Title: Preliminary report on the ground-water resources of the Klamath River Basin, Oregon Author: Newcomb, Reuben Clair Year: 1958, 2005 The Klamath River basin, including the adjacent Lost River basin, includes about ?,5>OO square miles of plateaus, mountain-slopes and valley plains in south-central Oregon* The valley plains range in altitude from about U,100 feet in the south to more than li,500 feet at the northern end; the mountain and plateau lands rise to an average altitude of 6,000 feet at the drainage divide, some peaks rising above 9*000 feet. The western quarter of the ba3in is on the eastern slope of the Cascade Range and the remainder consists of plateaus, mountains, and valleys of the basin-and-range type* The rocks of the Klamath River basin range in age from Recent to Mesozoic* At the southwest side of the basin in Oregon, pre~Tertiary metamorphic, igneous, and sedimentary rocks, which form extensive areas farther west, are overlain by sedimentary rocks of Eocene age and volcanic rocks of Eocene and Oligocene age* These early Tertiary rocks dip east toward the central part of the Klamath River basin. The complex "volcanic rocks of high Cascades" include three units: The lowest unit consists of a sequence of basaltic lava flows about 800 feet thick5 the medial unit is composed of volcanic-sedimentary and sedimentary rocks?the Tonna formation-200 to 2,000 feet thick; the uppermost unit is a sequence of basaltic lava flows commonly about 200 feet thick. These rocks dip east from the Cascade Unpublished records subject to revision 2 Range and are the main bedrock formations beneath most of the basin. Extensive pumice deposits, which emanated ^?^ ancestral Mount Mazaraa, cover large areas in the northwestern part of the basin* The basin has an overall synclinal structure open to the south at the California boundary where it continues as the Klamath Lake basin in California* The older rocks dip into the basin in monoclinal fashion from the adjoining drainage basins* The rocks are broken along rudely rectangular nets of closely spaced normal faults* the most prominent set of which trends northwest* The network of fault displacements includes two main grabens, the Klamath and the Langell, which were downthrown approximately ?00 and 1,000 fast, respectively* The average annual precipitation varies with the altitude, the higher parts of the Cascade Range getting more than 60 inches, and the semierid valley plains receive as little as 13 inches in some places* Most precipitation occurs in the winter. \ The principal tributaries, Williamson and Sprague Rivers, rise near the higher parts of the eastern rim of the basin, flow through narrow valley plains to the western part, and discharge into Upper Klamath Lake* Wood River and associated creeks also empty into Upper Klamath Lake after draining southward along the eastern foot of the Cascade Range* The Klamath River receives the outflow from Upper Klamath Lake, via Lifak River and Lake Ewauna, and flows southwestward through Keno Gap and hence through a youthful canyon, to its lower valley in California* The ground water occurs largely in an unconfined, or water-table, condition, though areas of local confinement are present* The regional Unpublished records subject to revis&oa is graded to water table / a base level about equal to that of the major drainage* where water is confined, on the valley plains. The slope of the water tafele, ~ of/the piezomstric surface is downstream at about the same grade as that "of the surface drainage in each of the larger valleys, attd groufid*water divides occur between the upper parts of adjacent major valleys* The principal water-bearipg units are.the'lower lava rocks and upper lava rocks of the "volcanic rocks of high Cascades,* the pumice of Quaternaryage, and the allusriTuju In places layers of coarse flagmental material in the Tonna formation (Newcorub, 1958) also transmit water* The water-bearing units, especially the breccia layers of the lava rocks and the pumice, yield large amounts of water to wells and provide natural discharge outlets for the ground water. The spring outflows to the Williamson and Wood Rivers-Crooked Creek drainage, measured in September and October 1955, were at a rate equivalent to about 700,000 acre-feet per year. The spring outflows into the Sprague River were at a rate equal to 2l;5>000 apre-feet per year* Large springs occur along the edges of Upper Klamath Lake but their discharges could not be measured, and the known spring discharge from the lower lava rocks in the river canyon below Keno was not measured. The spring discharge into Lost River in the reach ?rom Bonanza to Harpold Bridge was at a rate equivalent to 75,000 acre-feet per year. Much of the water discharged from springs is used for irrigation during the growing season, but ground water has not been extensively Unpublished records subject to revision developed by means of wells except in the'Yonna Valley and other local areas. The total withdrawal of ground water from wells in 1951? was only about 30,000 acre-feet, of which 27,000 was used for irrigation* The ground water is of excellent quality in general, but sodium sulfate water occurs in the belts of warm rock along some faults and alkali bicarbonate water is present in the main evapotranspiration basins. Unpublished records subject to revision Close