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211. [Image] Upper Klamath Lake Basin nutrient-loading study: assessment of historic flows in the Williamson and Sprague Rivers


	"The goal of the project is to quantitatively describe the nature and extent of the ground-water flow systems in the basin."
	Citation Citation Citation Abstract Copy Title: Upper Klamath Lake Basin nutrient-loading study: assessment of historic flows in the Williamson and Sprague Rivers Author: Risley, John C. Year: 1999, 2005, 2004 "The goal of the project is to quantitatively describe the nature and extent of the ground-water flow systems in the basin." Title: Upper Klamath Lake Basin nutrient-loading study: assessment of historic flows in the Williamson and Sprague Rivers Author: Risley, John C. Year: 1999, 2005, 2004 "The goal of the project is to quantitatively describe the nature and extent of the ground-water flow systems in the basin."

212. [Image] School-based Klamath River restoration project, phases V, VI & VII, 319h Clean Water Act


	ABSTRACT Phase VI of the School-Based Klamath Restoration Project (319h) is a collaborative effort between seven Siskiyou County schools, the Siskiyou County Office of Education (SCOE), and the United ...
	Citation Citation Citation Abstract Copy Title: School-based Klamath River restoration project, phases V, VI & VII, 319h Clean Water Act Author: Rilling, Trudy S. Year: 2000, 2005 ABSTRACT Phase VI of the School-Based Klamath Restoration Project (319h) is a collaborative effort between seven Siskiyou County schools, the Siskiyou County Office of Education (SCOE), and the United States Fish and Wildlife Service (USFWS). The objectives of the project include: ? Expanding hands-on field science watershed education. ? Encouraging a sense of resource stewardship among students at all grade levels. ? Collecting quality data for inclusion in the 319h data base. ? Teaching applications of the scientific method. ? Providing on-going inservice training for teachers to increase the effectiveness of the project. Project tasks that were completed include acquisition and analysis of Klamath River Watershed Data, including river water temperatures, river cross sectional profiles and spawning ground surveys. Descriptions of methodology are included in the report. Many other watershed-related projects were undertaken by schools. In some cases the field data was collected and compiled by agency personnel. The spawning ground survey data collected by student volunteers was part of a project conducted by the California Department of Fish and Game and the U.S. Forest Service. Although a substantial amount of excellent work has been accomplished by the schools, the opportunity exists to improve the program at all levels. Increased field and technical support is needed to successfully integrate the goals of the project. Computer training for teachers and students is an essential component of the project, which would allow analysis of data and creation of web sites within classrooms. Data analysis and reporting is the critical component of the project that would provide students with a complete understanding of scientific research methodology. Providing a forum for communication between the 319h participants is another important area of the project that needs to be expanded. Travel time, mountainous topography, and intense winter storms can be barriers to travel in Siskiyou County. Communication helps to increase the level of standardization of data collection and transfer and gives teachers a chance to share successful ideas. Communication also sustains the positive momentum of the project, reinforcing the idea of working as a team towards establishing common goals for watershed education. Title: School-based Klamath River restoration project, phases V, VI & VII, 319h Clean Water Act Author: Rilling, Trudy S. Year: 2000, 2005 ABSTRACT Phase VI of the School-Based Klamath Restoration Project (319h) is a collaborative effort between seven Siskiyou County schools, the Siskiyou County Office of Education (SCOE), and the United States Fish and Wildlife Service (USFWS). The objectives of the project include: ? Expanding hands-on field science watershed education. ? Encouraging a sense of resource stewardship among students at all grade levels. ? Collecting quality data for inclusion in the 319h data base. ? Teaching applications of the scientific method. ? Providing on-going inservice training for teachers to increase the effectiveness of the project. Project tasks that were completed include acquisition and analysis of Klamath River Watershed Data, including river water temperatures, river cross sectional profiles and spawning ground surveys. Descriptions of methodology are included in the report. Many other watershed-related projects were undertaken by schools. In some cases the field data was collected and compiled by agency personnel. The spawning ground survey data collected by student volunteers was part of a project conducted by the California Department of Fish and Game and the U.S. Forest Service. Although a substantial amount of excellent work has been accomplished by the schools, the opportunity exists to improve the program at all levels. Increased field and technical support is needed to successfully integrate the goals of the project. Computer training for teachers and students is an essential component of the project, which would allow analysis of data and creation of web sites within classrooms. Data analysis and reporting is the critical component of the project that would provide students with a complete understanding of scientific research methodology. Providing a forum for communication between the 319h participants is another important area of the project that needs to be expanded. Travel time, mountainous topography, and intense winter storms can be barriers to travel in Siskiyou County. Communication helps to increase the level of standardization of data collection and transfer and gives teachers a chance to share successful ideas. Communication also sustains the positive momentum of the project, reinforcing the idea of working as a team towards establishing common goals for watershed education.

213. [Image] Final progress report for fisheries investigations on Blue Creek, tributary to Klamath River, northern California, FY 1993


	FINAL PROGRESS REPORT FOR FISHERIES INVESTIGATIONS ON BLUE CREEK, TRIBUTARY TO K1AMATH RIVER, NORTHERN CALIFORNIA FY 1993 (October 1992 - September 1993) ABSTRACT The U.S. Fish and Wildlife Service, ...
	Citation Citation Citation Abstract Copy Title: Final progress report for fisheries investigations on Blue Creek, tributary to Klamath River, northern California, FY 1993 Author: Longenbaugh, Matthew H.; Chan, Jeffrey R. Year: 1994, 2008, 2005 FINAL PROGRESS REPORT FOR FISHERIES INVESTIGATIONS ON BLUE CREEK, TRIBUTARY TO K1AMATH RIVER, NORTHERN CALIFORNIA FY 1993 (October 1992 - September 1993) ABSTRACT The U.S. Fish and Wildlife Service, Coastal California Fishery Resource Office (CCFRO) in Arcata, CA, was funded to investigate chinook salmon spawning use, juvenile salmonid emigration and characterize habitats in Blue Creek, Klamath Basin, CA. Investigations that began in October, 1988, have continued to date, with this reporting period covering Fiscal Year 1993 (FY 1993, October, 1992, through September, 1993). In addition, some information already presented in previous progress reports, FY 1989 - FY 1992, is summarized. In 1993, adult chinook spawner escapements were addressed by snorkel surveys of redds and carcasses. Spawner numbers were very low, with only 17 redds observed in fall/winter 1992-93. The peak count of adult chinook was 136 fish in early November. Emigrating juvenile s&lmonids were trapped at river kilometer (rkm) 3.35 with a screw trap and panel weir. The screw trapping period extended from April through July for a total of 91 trapping nights. Screw trap catches totaled 14,526 chinook, 912 steelhead and 69 coho. Chinook emigration was spread over the entire trapping period, with increases during mid-May, and from mid-June throughout July. A juvenile weir was operated 60 nights, and caught a total of 6,334 chinook, 992 steelhead, 49 coho salmon, and 0 juvenile cutthroat. The total index of production for emigrating chinook during the 1993 juvenile trapping period was 101,819. Chinook that were marked with coded-wire tags (n-12,299) were released, with other juvenile fish, into Blue Creek at rkm 3.3. Mean temperatures varied from 6.3 to 18.6 ?C and flows ranged from 0.91 cubic m/s (32 cubic feet/s) to 202.6 cubic m/s (7,160 cubic feet/s) during FY 1993. Extreme flows for FY 1993 were the lowest and highest observed by CCFRO since the project began in 1989, and lower than the previous low of the 13 years of record. Title: Final progress report for fisheries investigations on Blue Creek, tributary to Klamath River, northern California, FY 1993 Author: Longenbaugh, Matthew H.; Chan, Jeffrey R. Year: 1994, 2008, 2005 FINAL PROGRESS REPORT FOR FISHERIES INVESTIGATIONS ON BLUE CREEK, TRIBUTARY TO K1AMATH RIVER, NORTHERN CALIFORNIA FY 1993 (October 1992 - September 1993) ABSTRACT The U.S. Fish and Wildlife Service, Coastal California Fishery Resource Office (CCFRO) in Arcata, CA, was funded to investigate chinook salmon spawning use, juvenile salmonid emigration and characterize habitats in Blue Creek, Klamath Basin, CA. Investigations that began in October, 1988, have continued to date, with this reporting period covering Fiscal Year 1993 (FY 1993, October, 1992, through September, 1993). In addition, some information already presented in previous progress reports, FY 1989 - FY 1992, is summarized. In 1993, adult chinook spawner escapements were addressed by snorkel surveys of redds and carcasses. Spawner numbers were very low, with only 17 redds observed in fall/winter 1992-93. The peak count of adult chinook was 136 fish in early November. Emigrating juvenile s&lmonids were trapped at river kilometer (rkm) 3.35 with a screw trap and panel weir. The screw trapping period extended from April through July for a total of 91 trapping nights. Screw trap catches totaled 14,526 chinook, 912 steelhead and 69 coho. Chinook emigration was spread over the entire trapping period, with increases during mid-May, and from mid-June throughout July. A juvenile weir was operated 60 nights, and caught a total of 6,334 chinook, 992 steelhead, 49 coho salmon, and 0 juvenile cutthroat. The total index of production for emigrating chinook during the 1993 juvenile trapping period was 101,819. Chinook that were marked with coded-wire tags (n-12,299) were released, with other juvenile fish, into Blue Creek at rkm 3.3. Mean temperatures varied from 6.3 to 18.6 ?C and flows ranged from 0.91 cubic m/s (32 cubic feet/s) to 202.6 cubic m/s (7,160 cubic feet/s) during FY 1993. Extreme flows for FY 1993 were the lowest and highest observed by CCFRO since the project began in 1989, and lower than the previous low of the 13 years of record.

214. [Image] Reports of explorations and surveys to ascertain the most practicable and economical route for a railroad from the Missisippi River to the Pacific Ocean / made under the direction of the Secretary of War, in 1853-4, according to acts of Congress of March 3, 1853, May 31, 1854, and August 5, 1854.


	Following is a digital file of the Report of Lieut. Henry L. Abbot, Corps of Topographical Engineers upon Explorations for a Railroad Route from the Sacramento Valley to the Columbia River, made by Lieut. ...
	Citation Citation Citation Abstract Copy Title: Reports of explorations and surveys to ascertain the most practicable and economical route for a railroad from the Missisippi River to the Pacific Ocean / made under the direction of the Secretary of War, in 1853-4, according to acts of Congress of March 3, 1853, May 31, 1854, and August 5, 1854. Author: United States. War Department Year: 1857, 2006, 2005 Following is a digital file of the Report of Lieut. Henry L. Abbot, Corps of Topographical Engineers upon Explorations for a Railroad Route from the Sacramento Valley to the Columbia River, made by Lieut. R. S. Williamson, Corps of Topographical Engineers, Assisted by Lieut. Henry L. Abbot, Corps of Topographical Engineers. This book was printed in 1855 and is volume six in the serial titled Reports of Explorations and Surveys, to Ascertain the Most Practicable and Economical Route for a Railroad from the Mississippi River to the Pacific Ocean. ; ill.; maps (some col.); Also known as: Pacific railroad surveys; Due to the delicate nature of this antique book and the physical stress created by scanning, only the portions relevant to the Klamath Basin were selected for scanning. Title: Reports of explorations and surveys to ascertain the most practicable and economical route for a railroad from the Missisippi River to the Pacific Ocean / made under the direction of the Secretary of War, in 1853-4, according to acts of Congress of March 3, 1853, May 31, 1854, and August 5, 1854. Author: United States. War Department Year: 1857, 2006, 2005 Following is a digital file of the Report of Lieut. Henry L. Abbot, Corps of Topographical Engineers upon Explorations for a Railroad Route from the Sacramento Valley to the Columbia River, made by Lieut. R. S. Williamson, Corps of Topographical Engineers, Assisted by Lieut. Henry L. Abbot, Corps of Topographical Engineers. This book was printed in 1855 and is volume six in the serial titled Reports of Explorations and Surveys, to Ascertain the Most Practicable and Economical Route for a Railroad from the Mississippi River to the Pacific Ocean. ; ill.; maps (some col.); Also known as: Pacific railroad surveys; Due to the delicate nature of this antique book and the physical stress created by scanning, only the portions relevant to the Klamath Basin were selected for scanning.

215. [Image] Water availability for Oregon's rivers and streams: Volume 1; Overview


	Title from cover; "May 1991."; Includes bibliographical references (p. 19)
	Citation Citation Citation Abstract Copy Title: Water availability for Oregon's rivers and streams: Volume 1; Overview Author: Robison, E. George Year: 1991, 2004 Title from cover; "May 1991."; Includes bibliographical references (p. 19) Title: Water availability for Oregon's rivers and streams: Volume 1; Overview Author: Robison, E. George Year: 1991, 2004 Title from cover; "May 1991."; Includes bibliographical references (p. 19)

216. [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"

217. [Image] Geology and ground-water resources of the Swan Lake-Yonna Valleys area, Klamath County, Oregon


	Abstract The Swan Lake-Yonna Valleys area consists of two intermountain valleys with their subordinate side valleys adjoining slopes, and mountainous boundary ridges, In all the area covered is about 256 ...
	Citation Citation Citation Abstract Copy Title: Geology and ground-water resources of the Swan Lake-Yonna Valleys area, Klamath County, Oregon Author: Meyers, Joseph D. Year: 1952, 2007, 2005 Abstract The Swan Lake-Yonna Valleys area consists of two intermountain valleys with their subordinate side valleys adjoining slopes, and mountainous boundary ridges, In all the area covered is about 256 square miles but the essential agricultural sections are restricted to the floors of Swan Lake and Yonna valleys with their respective subsidiary extensions of Pine Flats and Alkali Lake flats, a valley-floor area totaling about 90 square miles The floors of Swan Lake Valley and Yonna Valley lie at an altitude of about U52OO feet but the mountainous boundary ridges rise generally to 6000 feeto Yonna Valley is largely drained to Lost River by Buck Creek but also in part to Alkali Lakeo Swan Lake Valley and Pine Flats have only internal drainage. The Swan Lake Valley floor is the top of a deep alluvial fill, while Yonna Valley floor is mainly an erosional surface sloping to lines of through drainage Precipitation is about lit inches annually on the valley floors 9 but must be much more, possibly 18 to 24 inches, on the higher parts of the drainage basins. The growing season is short and killing frosts do occur in late spring and early fall. The rock units forming the bedrock structure of the area are consolidated or semiconsolidated rocks of Tertiary age and are largely of volcanic-flow and volcanic-sedimentary originc They consist of three main elements, a lower lava-rock unit, a sedimentary and volcanic-sedimentary unit, and an upper lava-rock unito The unconsolidated deposits are the older alluvium of Quaternary (and in part of late-Tertiary) age and the younger alluvium of Quaternary age0 The bedrock is faulted and deformed particularly so along a northwest-southeast set of fault lines that have given a remarkable linearity to the topography. Unpublished records subject to revision Ground water occurs below a regional water table that slopes south-ward to the level of the Lost Rivero The upper lava rocks and the lower lava rocks contain the principal permeable zones that occur beneath the areao Breccia and other porous zones in those rocks in places yield water to wells at a rate as large as 35OOO gallons per minute with but 1 or 2 feet of drawdowno The economical construction of irrigation wells requires the determination of the best possible location at which those rocks may be tapped at shallow depth below the level of the water tableo The ground water in general relatively low in dissolved mineral matter and is but slightly to moderately hard and would be considered chemically satisfactory for most uaeso Irrigation is the principal use of the ground water in the area north of the Horsefly Irrigation Districto There 3? wells supplied about 6,000 acre-feet of water to about 3800 acres of land in 1950. Water-level records obtained since 19U8 and approximations of the probable annual recharge from precipitation indicate that the present withdrawals are considerably less than the annual increment of the ground-water recharge, Rough estimates indicate that an increase in withdrawals of as much as 100 percent or more can take place before ground-water levels, by a persistent lowering, will begin to indicate that the annual replenishment is being exceeded. Title: Geology and ground-water resources of the Swan Lake-Yonna Valleys area, Klamath County, Oregon Author: Meyers, Joseph D. Year: 1952, 2007, 2005 Abstract The Swan Lake-Yonna Valleys area consists of two intermountain valleys with their subordinate side valleys adjoining slopes, and mountainous boundary ridges, In all the area covered is about 256 square miles but the essential agricultural sections are restricted to the floors of Swan Lake and Yonna valleys with their respective subsidiary extensions of Pine Flats and Alkali Lake flats, a valley-floor area totaling about 90 square miles The floors of Swan Lake Valley and Yonna Valley lie at an altitude of about U52OO feet but the mountainous boundary ridges rise generally to 6000 feeto Yonna Valley is largely drained to Lost River by Buck Creek but also in part to Alkali Lakeo Swan Lake Valley and Pine Flats have only internal drainage. The Swan Lake Valley floor is the top of a deep alluvial fill, while Yonna Valley floor is mainly an erosional surface sloping to lines of through drainage Precipitation is about lit inches annually on the valley floors 9 but must be much more, possibly 18 to 24 inches, on the higher parts of the drainage basins. The growing season is short and killing frosts do occur in late spring and early fall. The rock units forming the bedrock structure of the area are consolidated or semiconsolidated rocks of Tertiary age and are largely of volcanic-flow and volcanic-sedimentary originc They consist of three main elements, a lower lava-rock unit, a sedimentary and volcanic-sedimentary unit, and an upper lava-rock unito The unconsolidated deposits are the older alluvium of Quaternary (and in part of late-Tertiary) age and the younger alluvium of Quaternary age0 The bedrock is faulted and deformed particularly so along a northwest-southeast set of fault lines that have given a remarkable linearity to the topography. Unpublished records subject to revision Ground water occurs below a regional water table that slopes south-ward to the level of the Lost Rivero The upper lava rocks and the lower lava rocks contain the principal permeable zones that occur beneath the areao Breccia and other porous zones in those rocks in places yield water to wells at a rate as large as 35OOO gallons per minute with but 1 or 2 feet of drawdowno The economical construction of irrigation wells requires the determination of the best possible location at which those rocks may be tapped at shallow depth below the level of the water tableo The ground water in general relatively low in dissolved mineral matter and is but slightly to moderately hard and would be considered chemically satisfactory for most uaeso Irrigation is the principal use of the ground water in the area north of the Horsefly Irrigation Districto There 3? wells supplied about 6,000 acre-feet of water to about 3800 acres of land in 1950. Water-level records obtained since 19U8 and approximations of the probable annual recharge from precipitation indicate that the present withdrawals are considerably less than the annual increment of the ground-water recharge, Rough estimates indicate that an increase in withdrawals of as much as 100 percent or more can take place before ground-water levels, by a persistent lowering, will begin to indicate that the annual replenishment is being exceeded.

218. [Image] Soils of the Klamath Indian Reservation; interim report, June 11, 1958


	TABLE OF CONTENTS PART I INTRODUCTION 18 - 11 History and ethnology 18 Irrigated area table 19 Cultural geography 19 General physiographic features 262e . .3 Physiographic areas and farming 1d CLIMATE ...
	Citation Citation Citation Abstract Copy Title: Soils of the Klamath Indian Reservation; interim report, June 11, 1958 Author: United States. Bureau of Indian Affairs Year: 1958, 2005, 2004 TABLE OF CONTENTS PART I INTRODUCTION 18 - 11 History and ethnology 18 Irrigated area table 19 Cultural geography 19 General physiographic features 262e . .3 Physiographic areas and farming 1d CLIMATE 182 - 18 Climatic table, Sprague River, Oregon 185 Precipitation table , Chiloquin, Oregon 186 Temperature table, Chiloquin, Oregon 187 Climatic table, Fort Klamath, Oregon 188 VEGETATION 189 - 25 GEOLOGY 196 - 51 Hydrography: rivers, lakes, marshes, ground water 196 Relief and geological formations. 262e .32 Diatomite - tuff formation 262e . 1c4 Pliocene sediments of the Modoc Point area 262e.. 37 Faulted tuff formation 1c9 Pumice tuff formation.. 1d0 Pumice mantle and pumice flows ........ 262e.... .........40 Table of chemical analyses of pumice and scoria 1d5 Geology Map 262e . 262e 221 BIBLIOGRAPHY 262e 262e...52 PART II DESCRIPTIONS OF SOILS 223 - 60 Classification and survey 262e 262e.. 262e... 53 Soil profile and nomenclature. .... 262e...53 Chestnut Soils 262e 224 "Western" Brown Forest Soils 225 Regosol Soils . . 262e. 262e......56 Solonetz Soils 262e.....57 Halomorphic Soils 262e 228 Hydromorphic Soils 262e... 229 Soil Association Map 262e 229 KEY TO SOIL SERIES 262e61 - 63 SOIL SERIES AND MAPPING UNIT DESCRIPTIONS 134 ~ 254 APPENDIX 1955 - 297 Soil Series and mapping unit index. 2620. . . . 255 Glossary of terms 263f 262e. . . . 272 Table of soil analyses (Oregon State College)... 1989 Table of irrigation water quality (Oregon State College) 1990 Table of conductivity and reaction. . . . 1991 Table of resistance of saturated paste 262e296 Title: Soils of the Klamath Indian Reservation; interim report, June 11, 1958 Author: United States. Bureau of Indian Affairs Year: 1958, 2005, 2004 TABLE OF CONTENTS PART I INTRODUCTION 18 - 11 History and ethnology 18 Irrigated area table 19 Cultural geography 19 General physiographic features 262e . .3 Physiographic areas and farming 1d CLIMATE 182 - 18 Climatic table, Sprague River, Oregon 185 Precipitation table , Chiloquin, Oregon 186 Temperature table, Chiloquin, Oregon 187 Climatic table, Fort Klamath, Oregon 188 VEGETATION 189 - 25 GEOLOGY 196 - 51 Hydrography: rivers, lakes, marshes, ground water 196 Relief and geological formations. 262e .32 Diatomite - tuff formation 262e . 1c4 Pliocene sediments of the Modoc Point area 262e.. 37 Faulted tuff formation 1c9 Pumice tuff formation.. 1d0 Pumice mantle and pumice flows ........ 262e.... .........40 Table of chemical analyses of pumice and scoria 1d5 Geology Map 262e . 262e 221 BIBLIOGRAPHY 262e 262e...52 PART II DESCRIPTIONS OF SOILS 223 - 60 Classification and survey 262e 262e.. 262e... 53 Soil profile and nomenclature. .... 262e...53 Chestnut Soils 262e 224 "Western" Brown Forest Soils 225 Regosol Soils . . 262e. 262e......56 Solonetz Soils 262e.....57 Halomorphic Soils 262e 228 Hydromorphic Soils 262e... 229 Soil Association Map 262e 229 KEY TO SOIL SERIES 262e61 - 63 SOIL SERIES AND MAPPING UNIT DESCRIPTIONS 134 ~ 254 APPENDIX 1955 - 297 Soil Series and mapping unit index. 2620. . . . 255 Glossary of terms 263f 262e. . . . 272 Table of soil analyses (Oregon State College)... 1989 Table of irrigation water quality (Oregon State College) 1990 Table of conductivity and reaction. . . . 1991 Table of resistance of saturated paste 262e296

219. [Image] Effect of water-column pH on sediment-phosphorus release rates in Upper Klamath Lake, Oregon, 2001


	Abstract Sediment-phosphorus release rates as a function of pH were determined in laboratory experiments for sediment and water samples collected from Shoalwater Bay in Upper Klamath Lake, Oregon, in 2001. ...
	Citation Citation Citation Abstract Copy Title: Effect of water-column pH on sediment-phosphorus release rates in Upper Klamath Lake, Oregon, 2001 Author: Fisher, Lawrence H. Year: 2004, 2005 Abstract Sediment-phosphorus release rates as a function of pH were determined in laboratory experiments for sediment and water samples collected from Shoalwater Bay in Upper Klamath Lake, Oregon, in 2001. Areal release rates for a stable sediment/water interface that is representative of the sediment surface area to water column volume ratio (1:3) observed in the lake and volumetric release rates for resuspended sediment events were determined at three different pH values (8.1, 9.2, 10.2). Ambient water column pH (8.1) was maintained by sparging study columns with atmospheric air. Elevation of the water column pH to 9.2 was achieved through the removal of dissolved carbon dioxide by sparging with carbon dioxide-reduced air, partially simulating water chemistry changes that occur during algal photosynthesis. Further elevation of the pH to 10.2 was achieved by the addition of sodium hydroxide, which doubled average alkalinities in the study columns from about 1 to 2 milliequivalents per liter. Upper Klamath Lake sediments collected from the lake bottom and then placed in contact with lake water, either at a stable sediment/water interface or by resus-pension, exhibited an initial capacity to take up soluble reactive phosphorus (SRP) from the water column rather than release phosphorus to the water column. At a higher pH this initial uptake of phosphorus was slowed, but not stopped. This initial phase was followed by a reversal in which the sediments began to release SRP back into the water column. The release rate of phosphorus 30 to 40 days after suspension of sediments in the columns was 0.5 \|ig/L/day (micrograms per liter per day) at pH 8, and 0.9 \|ug/L/day at pH 10, indicating that the higher pH increased the rate of phosphorus release by a factor of about two. The highest determined rate of release was approximately 10% (percent) of the rate required to explain the annual internal loading to Upper Klamath Lake from the sediments as calculated from a lake-wide mass balance and observed in total phosphorus data collected at individual locations. Title: Effect of water-column pH on sediment-phosphorus release rates in Upper Klamath Lake, Oregon, 2001 Author: Fisher, Lawrence H. Year: 2004, 2005 Abstract Sediment-phosphorus release rates as a function of pH were determined in laboratory experiments for sediment and water samples collected from Shoalwater Bay in Upper Klamath Lake, Oregon, in 2001. Areal release rates for a stable sediment/water interface that is representative of the sediment surface area to water column volume ratio (1:3) observed in the lake and volumetric release rates for resuspended sediment events were determined at three different pH values (8.1, 9.2, 10.2). Ambient water column pH (8.1) was maintained by sparging study columns with atmospheric air. Elevation of the water column pH to 9.2 was achieved through the removal of dissolved carbon dioxide by sparging with carbon dioxide-reduced air, partially simulating water chemistry changes that occur during algal photosynthesis. Further elevation of the pH to 10.2 was achieved by the addition of sodium hydroxide, which doubled average alkalinities in the study columns from about 1 to 2 milliequivalents per liter. Upper Klamath Lake sediments collected from the lake bottom and then placed in contact with lake water, either at a stable sediment/water interface or by resus-pension, exhibited an initial capacity to take up soluble reactive phosphorus (SRP) from the water column rather than release phosphorus to the water column. At a higher pH this initial uptake of phosphorus was slowed, but not stopped. This initial phase was followed by a reversal in which the sediments began to release SRP back into the water column. The release rate of phosphorus 30 to 40 days after suspension of sediments in the columns was 0.5 \|ig/L/day (micrograms per liter per day) at pH 8, and 0.9 \|ug/L/day at pH 10, indicating that the higher pH increased the rate of phosphorus release by a factor of about two. The highest determined rate of release was approximately 10% (percent) of the rate required to explain the annual internal loading to Upper Klamath Lake from the sediments as calculated from a lake-wide mass balance and observed in total phosphorus data collected at individual locations.