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• 4311. [Image] Report on payment capacity for Tule Lake irrigation district, Klamath Project

  	SUMMARY To provide a basis for negotiations of a repayment contract with an irrigation district representing the water users of the Tule Lake Division of the Klamath Project, this report has been prepared. ...
  	Citation × Citation Citation Abstract Copy Title: Report on payment capacity for Tule Lake irrigation district, Klamath Project Author: Best, R.R. Year: 1948, 2004 SUMMARY To provide a basis for negotiations of a repayment contract with an irrigation district representing the water users of the Tule Lake Division of the Klamath Project, this report has been prepared. It covers past, present, and anticipated future agricultural and economic conditions and substantiates the proposed district's capacity to repay construction costs for irrigation water as well as to meet operation and maintenance charges It has been prepared according to procedures and policies established pursuant to the Federal Reclamation laws (Act of June 17, 1902, 32 Stat. 388, and acts amendatory thereof and supplementary thereto.) In general, a representative farm budget method of analysis was employed to determine the payment capacity* Gross income of the land was based upon average per acre yields in the area and 1939-44 prices received. Prices of certain crops were adjusted further in accordance with long term outlook for these crops. From the gross income, all farm operating and retention expenses, including cultural and harvesting costs, taxes, insurance, depreciation and replacement, interest on investment, and a reasonable allowance for family living predicated upon the same base period (1939-44) have been subtracted to arrive at payment capacity. Individual consideration has been given to the block of land entered prior to 1948 (the major portion of the area), the lands of the Coppock Bay Area which are principally Class 2, and the undeveloped lands of the area just south of Malin, Oregon, Area C, Plate 1. The annual payment capacity of the irrigable lands entered prior to 1914-8, is determined to be approximately $50 per acre. The Class 2 lands of the Coppock Bay Area are shown to have a payment capacity of $21 per acre, as a result of slightly higher operating costs and probable lower yield or quality of certain crops. For the undeveloped area just south of Malin, Area C of Plate 1, the payment capacity is determined at $18 per acre after development to the extent expected under settlement and development plans currently being formulated The weighted average payment capacity for these areas is calculated to be $26.25 per acre. There is no need for a development period for the lands of the Tule Lake Division, except for the latter area as indicated above. Furthermore, after liberal allowance for farming costs and a reasonable family living, the resulting payment capacities appear to be well in excess of any annual installments likely to be considered necessary for repayment of the District's construction obligation and operation and maintenance charges. Title: Report on payment capacity for Tule Lake irrigation district, Klamath Project Author: Best, R.R. Year: 1948, 2004 SUMMARY To provide a basis for negotiations of a repayment contract with an irrigation district representing the water users of the Tule Lake Division of the Klamath Project, this report has been prepared. It covers past, present, and anticipated future agricultural and economic conditions and substantiates the proposed district's capacity to repay construction costs for irrigation water as well as to meet operation and maintenance charges It has been prepared according to procedures and policies established pursuant to the Federal Reclamation laws (Act of June 17, 1902, 32 Stat. 388, and acts amendatory thereof and supplementary thereto.) In general, a representative farm budget method of analysis was employed to determine the payment capacity* Gross income of the land was based upon average per acre yields in the area and 1939-44 prices received. Prices of certain crops were adjusted further in accordance with long term outlook for these crops. From the gross income, all farm operating and retention expenses, including cultural and harvesting costs, taxes, insurance, depreciation and replacement, interest on investment, and a reasonable allowance for family living predicated upon the same base period (1939-44) have been subtracted to arrive at payment capacity. Individual consideration has been given to the block of land entered prior to 1948 (the major portion of the area), the lands of the Coppock Bay Area which are principally Class 2, and the undeveloped lands of the area just south of Malin, Oregon, Area C, Plate 1. The annual payment capacity of the irrigable lands entered prior to 1914-8, is determined to be approximately $50 per acre. The Class 2 lands of the Coppock Bay Area are shown to have a payment capacity of $21 per acre, as a result of slightly higher operating costs and probable lower yield or quality of certain crops. For the undeveloped area just south of Malin, Area C of Plate 1, the payment capacity is determined at $18 per acre after development to the extent expected under settlement and development plans currently being formulated The weighted average payment capacity for these areas is calculated to be $26.25 per acre. There is no need for a development period for the lands of the Tule Lake Division, except for the latter area as indicated above. Furthermore, after liberal allowance for farming costs and a reasonable family living, the resulting payment capacities appear to be well in excess of any annual installments likely to be considered necessary for repayment of the District's construction obligation and operation and maintenance charges. Close

• 4312. [Image] The Third Klamath Basin Watershed Restoration and Research Conference

  	Cover title; "March 1999."
  	Citation × Citation Citation Abstract Copy Title: The Third Klamath Basin Watershed Restoration and Research Conference Year: 1999, 2004 Cover title; "March 1999." Title: The Third Klamath Basin Watershed Restoration and Research Conference Year: 1999, 2004 Cover title; "March 1999." Close

• 4313. [Image] Evaluation of interim instream flow needs in the Klamath River : Phase I, final report

  	"August 5, 1999"
  	Citation × Citation Citation Abstract Copy Title: Evaluation of interim instream flow needs in the Klamath River : Phase I, final report Author: United States. Dept. of the Interior Year: 1999, 2005 "August 5, 1999" Title: Evaluation of interim instream flow needs in the Klamath River : Phase I, final report Author: United States. Dept. of the Interior Year: 1999, 2005 "August 5, 1999" Close

• 4314. [Image] Salmon of the Klamath river, California : 1. The salmon and the fishery of Klamath river. 2. A report on the 1930 catch of king salmon in Klamath river

  	CONTENTS PAGE I. THE SALMON AND THE FISHERY OF KLAMATH RIVER 2695 Introduction 2697 General Characteristics of Klamath River Salmon 2699 Species Other Than King Salmon 26916 The Spring Migration (Immigration) ...
  	Citation × Citation Citation Abstract Copy Title: Salmon of the Klamath river, California : 1. The salmon and the fishery of Klamath river. 2. A report on the 1930 catch of king salmon in Klamath river Author: Snyder, John Otterbein Year: 1931, 2005 CONTENTS PAGE I. THE SALMON AND THE FISHERY OF KLAMATH RIVER 2695 Introduction 2697 General Characteristics of Klamath River Salmon 2699 Species Other Than King Salmon 26916 The Spring Migration (Immigration) 26918 The Summer Migration (Immigration) 26923 Sex Representation in the Migration 26933 Fish Increase in Average Weight and Size as the Season Advances 26939 Angling for Salmon 26943 Seaward Migration (Emigration) 26944 Obstructions in the River 26950 The Age at Maturity of Klamath King Salmon 26952 Marking Experiments 26967 Experiment in 1916 26968 Experiment in 1918 26968 Experiment in 1919 26968 Experiment in 1920 26968 Experiment in 1922 (Sacramento River) 26971 Experiment in 1922 (Klamath River) 26972 Experiment in 1923-1924 269 143 Ocean Tagging 26980 Depletion 26981 Notes Relating to the Salmon Catch of Klamath River 26988 The Ocean Catch 26992 Age Characteristics of the Ocean Catch 269108 Artificial Propagation in Klamath River 269111 Summary 18 269119 II. A REPORT ON THE 1930 CATCH OF KING SALMON IN KLAMATH RIVER 1823 Title: Salmon of the Klamath river, California : 1. The salmon and the fishery of Klamath river. 2. A report on the 1930 catch of king salmon in Klamath river Author: Snyder, John Otterbein Year: 1931, 2005 CONTENTS PAGE I. THE SALMON AND THE FISHERY OF KLAMATH RIVER 2695 Introduction 2697 General Characteristics of Klamath River Salmon 2699 Species Other Than King Salmon 26916 The Spring Migration (Immigration) 26918 The Summer Migration (Immigration) 26923 Sex Representation in the Migration 26933 Fish Increase in Average Weight and Size as the Season Advances 26939 Angling for Salmon 26943 Seaward Migration (Emigration) 26944 Obstructions in the River 26950 The Age at Maturity of Klamath King Salmon 26952 Marking Experiments 26967 Experiment in 1916 26968 Experiment in 1918 26968 Experiment in 1919 26968 Experiment in 1920 26968 Experiment in 1922 (Sacramento River) 26971 Experiment in 1922 (Klamath River) 26972 Experiment in 1923-1924 269 143 Ocean Tagging 26980 Depletion 26981 Notes Relating to the Salmon Catch of Klamath River 26988 The Ocean Catch 26992 Age Characteristics of the Ocean Catch 269108 Artificial Propagation in Klamath River 269111 Summary 18 269119 II. A REPORT ON THE 1930 CATCH OF KING SALMON IN KLAMATH RIVER 1823 Close

• 4315. [Image] Oregon lampreys : natural history, status, and analysis of management issues

  	Executive Summary The jawless lampreys are remnants of the oldest vertebrates in the world. Oregon has somewhere between eight and a dozen species of these primitive fishes. Their taxonomy is obscure ...
  	Citation × Citation Citation Abstract Copy Title: Oregon lampreys : natural history, status, and analysis of management issues Author: Kostow, Kathryn Year: 2002, 2008, 2005 Executive Summary The jawless lampreys are remnants of the oldest vertebrates in the world. Oregon has somewhere between eight and a dozen species of these primitive fishes. Their taxonomy is obscure because different species tend to look very similar through most of their life cycle, and they have not been well-studied in Oregon. Lampreys occur in the Columbia Basin, including the lower Snake River, along the Oregon coast, in the upper Klamath Basin, and in Goose Lake Basin in southeastern Oregon. They all begin life in fresh water where juveniles burrow into silt and filter feed on algae. As some species approach adulthood they migrate to the ocean or to lakes where they briefly become ecto-parasites, feeding on other live fishes by attaching to them with sucker disc mouths. Other species remain non-parasitic. In addition to some enigmatic species identities, we generally have very little information about the detailed distributions, life histories and basic biology of lampreys. Lampreys became a conservation concern in the early 1990s when tribal co-managers and some Oregon Department of Fish and Wildlife (ODFW) staff noted that populations of Pacific Lampreys, Lampetra tridentata, were apparently declining to perilously low numbers. Pacific Lampreys were listed as an Oregon State sensitive species in 1993 and were given further legal protected status by the state in 1997 (OAR 635-044-0130). Lamprey status is difficult to assess for several reasons: 1) Most observations of lampreys in fresh water are of juveniles and it is difficult to tell the various species apart, even to the extent that the various species are currently clearly designated; 2) Data on lamprey is only collected incidental to monitoring of salmonids. The design and efficiency of the data collection effort is not always adequate for lampreys; and 3) We have very few historic data sets for lampreys. Therefore we often cannot determine how the abundances and distributions we see now compare with those in the past. The limited data that we have suggests that lampreys have declined through many parts of their ranges. The most precipitous declines appear to be in the upper Columbia and Snake basins where we have some historic data from mainstem dam counts. Pacific Lampreys have declined to only about 200 adults annually passing the Snake River dams. We also have evidence of declines of Pacific Lampreys in the lower Columbia and on the Oregon coast, although our data is quite limited. We have little to no information about any of the other species of lampreys. We are not even sure whether some of the recognized species, like the River Lamprey (L. ayresi), is still present in Oregon. This paper concludes with a Problem Analysis for Oregon lampreys. Our biggest problem is poor information, ranging from not knowing basic species identity to having inefficient or no systematic monitoring of lamprey abundance and distribution. ODFW continued an annual harvest on Pacific Lamprey in the Willamette Basin in 2001, but we lack the necessary information to assess the affects of the harvest on the population. Major habitat problems that affect lampreys include upstream passage over artificial barriers, a need for lamprey-friendly screening of water diversions, and urban and agricultural development of low-gradient flood plain habitats. Title: Oregon lampreys : natural history, status, and analysis of management issues Author: Kostow, Kathryn Year: 2002, 2008, 2005 Executive Summary The jawless lampreys are remnants of the oldest vertebrates in the world. Oregon has somewhere between eight and a dozen species of these primitive fishes. Their taxonomy is obscure because different species tend to look very similar through most of their life cycle, and they have not been well-studied in Oregon. Lampreys occur in the Columbia Basin, including the lower Snake River, along the Oregon coast, in the upper Klamath Basin, and in Goose Lake Basin in southeastern Oregon. They all begin life in fresh water where juveniles burrow into silt and filter feed on algae. As some species approach adulthood they migrate to the ocean or to lakes where they briefly become ecto-parasites, feeding on other live fishes by attaching to them with sucker disc mouths. Other species remain non-parasitic. In addition to some enigmatic species identities, we generally have very little information about the detailed distributions, life histories and basic biology of lampreys. Lampreys became a conservation concern in the early 1990s when tribal co-managers and some Oregon Department of Fish and Wildlife (ODFW) staff noted that populations of Pacific Lampreys, Lampetra tridentata, were apparently declining to perilously low numbers. Pacific Lampreys were listed as an Oregon State sensitive species in 1993 and were given further legal protected status by the state in 1997 (OAR 635-044-0130). Lamprey status is difficult to assess for several reasons: 1) Most observations of lampreys in fresh water are of juveniles and it is difficult to tell the various species apart, even to the extent that the various species are currently clearly designated; 2) Data on lamprey is only collected incidental to monitoring of salmonids. The design and efficiency of the data collection effort is not always adequate for lampreys; and 3) We have very few historic data sets for lampreys. Therefore we often cannot determine how the abundances and distributions we see now compare with those in the past. The limited data that we have suggests that lampreys have declined through many parts of their ranges. The most precipitous declines appear to be in the upper Columbia and Snake basins where we have some historic data from mainstem dam counts. Pacific Lampreys have declined to only about 200 adults annually passing the Snake River dams. We also have evidence of declines of Pacific Lampreys in the lower Columbia and on the Oregon coast, although our data is quite limited. We have little to no information about any of the other species of lampreys. We are not even sure whether some of the recognized species, like the River Lamprey (L. ayresi), is still present in Oregon. This paper concludes with a Problem Analysis for Oregon lampreys. Our biggest problem is poor information, ranging from not knowing basic species identity to having inefficient or no systematic monitoring of lamprey abundance and distribution. ODFW continued an annual harvest on Pacific Lamprey in the Willamette Basin in 2001, but we lack the necessary information to assess the affects of the harvest on the population. Major habitat problems that affect lampreys include upstream passage over artificial barriers, a need for lamprey-friendly screening of water diversions, and urban and agricultural development of low-gradient flood plain habitats. Close

• 4316. [Image] Gerber-Willow Valley Watershed Analysis

  	x, 386 p., ill., maps (some col.); Cover title; "July 2003"
  	Citation × Citation Citation Abstract Copy Title: Gerber-Willow Valley Watershed Analysis Author: U.S. Department of the Interior. Bureau of Land Management; Klamath Falls Resource Area Office; U.S. Department of Agriculture. Forest Service; Fremont-Winema National Forests; Modoc National Forest Year: 2003, 2006, 2005 x, 386 p., ill., maps (some col.); Cover title; "July 2003" Title: Gerber-Willow Valley Watershed Analysis Author: U.S. Department of the Interior. Bureau of Land Management; Klamath Falls Resource Area Office; U.S. Department of Agriculture. Forest Service; Fremont-Winema National Forests; Modoc National Forest Year: 2003, 2006, 2005 x, 386 p., ill., maps (some col.); Cover title; "July 2003" Close

• 4317. [Image] Agreement with Indians of Klamath Reservation, Oregon

  	"Mr. Moody, of Oregon, from the Committee on Indian Affairs, submitted the following report, to accompany H.R. 8760"
  	Citation × Citation Citation Abstract Copy Title: Agreement with Indians of Klamath Reservation, Oregon Author: United States. Congress. House. Committee on Indian Affairs Year: 1902, 2004 "Mr. Moody, of Oregon, from the Committee on Indian Affairs, submitted the following report, to accompany H.R. 8760" Title: Agreement with Indians of Klamath Reservation, Oregon Author: United States. Congress. House. Committee on Indian Affairs Year: 1902, 2004 "Mr. Moody, of Oregon, from the Committee on Indian Affairs, submitted the following report, to accompany H.R. 8760" Close

• 4318. [Image] Water allocation in the Klamath Reclamation Project, 2001 : an assessment of natural resource, economic, social, and institutional issues with a focus on the Upper Klamath Basin

  	"Reprinted May 2003."; Includes bibliographical references; Also available at http://eesc.oregonstate.edu/agcomwebfile/edmat/html/sr/sr1037/sr1037.html
  	Citation × Citation Citation Abstract Copy Title: Water allocation in the Klamath Reclamation Project, 2001 : an assessment of natural resource, economic, social, and institutional issues with a focus on the Upper Klamath Basin Author: Braunworth, William S. Year: 2003, 2004 "Reprinted May 2003."; Includes bibliographical references; Also available at http://eesc.oregonstate.edu/agcomwebfile/edmat/html/sr/sr1037/sr1037.html Title: Water allocation in the Klamath Reclamation Project, 2001 : an assessment of natural resource, economic, social, and institutional issues with a focus on the Upper Klamath Basin Author: Braunworth, William S. Year: 2003, 2004 "Reprinted May 2003."; Includes bibliographical references; Also available at http://eesc.oregonstate.edu/agcomwebfile/edmat/html/sr/sr1037/sr1037.html Close

• 4319. [Image] Nitrogen and phosphorus loading from drained wetlands adjacent to Upper Klamath and Agency Lakes, Oregon

  	Two maps digitized separately; Includes bibliographical references (p. 44-49)
  	Citation × Citation Citation Abstract Copy Title: Nitrogen and phosphorus loading from drained wetlands adjacent to Upper Klamath and Agency Lakes, Oregon Author: Snyder, Daniel T. Year: 1997, 2005, 2004 Two maps digitized separately; Includes bibliographical references (p. 44-49) Title: Nitrogen and phosphorus loading from drained wetlands adjacent to Upper Klamath and Agency Lakes, Oregon Author: Snyder, Daniel T. Year: 1997, 2005, 2004 Two maps digitized separately; Includes bibliographical references (p. 44-49) Close

• 4320. [Image] Relation between selected water-quality variables and lake level in Upper Klamath and Agency Lakes, Oregon

  	Relation Between Selected Water-Quality Constituents and Lake Stage in Upper Klamath and Agency Lakes, Oregon By Tamara M. Wood, Gregory J. Fuhrer, and Jennifer L. Morace SUMMARY Upper Klamath Lake is ...
  	Citation × Citation Citation Abstract Copy Title: Relation between selected water-quality variables and lake level in Upper Klamath and Agency Lakes, Oregon Author: Wood, Tamara M. Year: 1996, 2005, 2004 Relation Between Selected Water-Quality Constituents and Lake Stage in Upper Klamath and Agency Lakes, Oregon By Tamara M. Wood, Gregory J. Fuhrer, and Jennifer L. Morace SUMMARY Upper Klamath Lake is a large (140 square-mile), shallow (mean depth about 8 ft) lake in south-central Oregon that the historical record indicates has been eutrophic since its discovery by non-Native Americans. In recent decades, however, the lake has had annual occurrences of near-monoculture blooms of the blue-green alga Aphanizomenon flos-aquae. In 1988 two sucker species endemic to the lake, the Lost River sucker (Deltistes luxatus) and the shortnose sucker (Chasmistes brevirostris), were listed as endangered by the U.S. Fish and Wildlife Service, and it has been proposed that the poor water quality conditions associated with extremely long and productive blooms are contributing to the decline of those species. It has also been proposed that the low lake levels made possible by the construction of a dam at the outlet from the lake in 1921 have contributed to worsening water quality through a variety of possible mechanisms (Jacob Kann, Klamath Tribes, written com-mun., 1995). One such mechanism would be an increase in internal phosphorus loading from resuspended sediments (Jacoby and others, 1982), resulting from an increase in bottom shear stresses at lower lake levels (Laenen and LeTourneau, 1996), leading in turn to more intense algal blooms. Another possible mechanism is an earlier triggering of algal blooms. When early spring lake levels are low, greater light intensity at the sediment surface might speed recruitment of algal cells from the sediments. Sediment recruitment has been shown to be an important contributor to water column biomass increases in A. flos aquae (Barbiero and Kann, 1994) and Gloeotrichia echinulata (Barbiero, 1993). An earlier bloom could result in poor water quality conditions occurring earlier in the year, when young-of-the-year fish may be more susceptible to those conditions. Lake level can also influence water quality directly. An increased frequency of sediment resuspension at lower lake levels could increase chemical and biological oxygen demand, resulting in decreased dissolved oxygen concentrations. Sediment oxygen demand also may be enhanced at lower lake levels because it is concentrated over a smaller volume of water. Some compensation for increased oxygen demand at lower lake levels might be provided by increased reaeration, if the water column mixes from top to bottom more frequently. Based on the analysis of data that they have been collecting for several years, the Klamath Tribes recently recommended that the Bureau of Reclamation (Reclamation) modify the operating plan for the dam to make the minimum lake levels for the June-August period more closely resemble pre-dam conditions (Jacob Kann, written commun., 1995). The U.S. Geological Survey (USGS) was asked to analyze the available data for the lake and to assess whether the evidence exists to conclude that year-to-year differences in certain lake water-quality variables are related to year-to-year differences in lake level. The results of the analysis will be used as scientific input in the process of developing an operating plan for the Link River Dam. Datasets Two water-quality datasets were analyzed. The first was a series of hourly records of pH, dissolved oxygen, and water temperature, each of approximately a week's duration. The records were collected at 3 sites over 3 years, 1992 through 1994, with enough consistency to define the seasonal patterns. This dataset provided information about the diel extremes in dissolved oxygen and pH and the seasonal pattern in the diel cycle, but measurements were limited to a depth of 1 m(3.28 ft). The second dataset was a set of depth profiles of pH and dissolved oxygen and concurrent depth-integrated samples for nutrients and chlo-rophyll-a. The profiles were collected at approximately biweekly intervals at nine sites (seven in Upper Klamath and two in Agency Lake) over the 5 years 1990 through 1994. These depth profiles provided information on the depth-dependence of dissolved oxygen and pH, and allowed more extensive year-to-year comparisons than did the hourly records. Because measurements were made at each site only once during the sampling day, however, they did not capture the daily extremes in water quality. Lake level is measured daily by the USGS at three sites around the lake: Rocky Point, Rattlesnake Point, and near the city of Klamath Falls. These daily measurements are then used to compute a spatially weighted average of the lake level that is reported in the USGS annual Water-Data Report for Oregon. The average lake levels were used in this report. Two climatic datasets were used in this report; both were collected at the Klamath Falls airport. Air temperature was recorded as a daily maximum and daily minimum value. Cloud cover was quantized on a daily basis into one of seven levels. Because the focus of this study was primarily to examine possible relations between water quality and lake level, the lake level data provide an important context for the discussions that follow. Title: Relation between selected water-quality variables and lake level in Upper Klamath and Agency Lakes, Oregon Author: Wood, Tamara M. Year: 1996, 2005, 2004 Relation Between Selected Water-Quality Constituents and Lake Stage in Upper Klamath and Agency Lakes, Oregon By Tamara M. Wood, Gregory J. Fuhrer, and Jennifer L. Morace SUMMARY Upper Klamath Lake is a large (140 square-mile), shallow (mean depth about 8 ft) lake in south-central Oregon that the historical record indicates has been eutrophic since its discovery by non-Native Americans. In recent decades, however, the lake has had annual occurrences of near-monoculture blooms of the blue-green alga Aphanizomenon flos-aquae. In 1988 two sucker species endemic to the lake, the Lost River sucker (Deltistes luxatus) and the shortnose sucker (Chasmistes brevirostris), were listed as endangered by the U.S. Fish and Wildlife Service, and it has been proposed that the poor water quality conditions associated with extremely long and productive blooms are contributing to the decline of those species. It has also been proposed that the low lake levels made possible by the construction of a dam at the outlet from the lake in 1921 have contributed to worsening water quality through a variety of possible mechanisms (Jacob Kann, Klamath Tribes, written com-mun., 1995). One such mechanism would be an increase in internal phosphorus loading from resuspended sediments (Jacoby and others, 1982), resulting from an increase in bottom shear stresses at lower lake levels (Laenen and LeTourneau, 1996), leading in turn to more intense algal blooms. Another possible mechanism is an earlier triggering of algal blooms. When early spring lake levels are low, greater light intensity at the sediment surface might speed recruitment of algal cells from the sediments. Sediment recruitment has been shown to be an important contributor to water column biomass increases in A. flos aquae (Barbiero and Kann, 1994) and Gloeotrichia echinulata (Barbiero, 1993). An earlier bloom could result in poor water quality conditions occurring earlier in the year, when young-of-the-year fish may be more susceptible to those conditions. Lake level can also influence water quality directly. An increased frequency of sediment resuspension at lower lake levels could increase chemical and biological oxygen demand, resulting in decreased dissolved oxygen concentrations. Sediment oxygen demand also may be enhanced at lower lake levels because it is concentrated over a smaller volume of water. Some compensation for increased oxygen demand at lower lake levels might be provided by increased reaeration, if the water column mixes from top to bottom more frequently. Based on the analysis of data that they have been collecting for several years, the Klamath Tribes recently recommended that the Bureau of Reclamation (Reclamation) modify the operating plan for the dam to make the minimum lake levels for the June-August period more closely resemble pre-dam conditions (Jacob Kann, written commun., 1995). The U.S. Geological Survey (USGS) was asked to analyze the available data for the lake and to assess whether the evidence exists to conclude that year-to-year differences in certain lake water-quality variables are related to year-to-year differences in lake level. The results of the analysis will be used as scientific input in the process of developing an operating plan for the Link River Dam. Datasets Two water-quality datasets were analyzed. The first was a series of hourly records of pH, dissolved oxygen, and water temperature, each of approximately a week's duration. The records were collected at 3 sites over 3 years, 1992 through 1994, with enough consistency to define the seasonal patterns. This dataset provided information about the diel extremes in dissolved oxygen and pH and the seasonal pattern in the diel cycle, but measurements were limited to a depth of 1 m(3.28 ft). The second dataset was a set of depth profiles of pH and dissolved oxygen and concurrent depth-integrated samples for nutrients and chlo-rophyll-a. The profiles were collected at approximately biweekly intervals at nine sites (seven in Upper Klamath and two in Agency Lake) over the 5 years 1990 through 1994. These depth profiles provided information on the depth-dependence of dissolved oxygen and pH, and allowed more extensive year-to-year comparisons than did the hourly records. Because measurements were made at each site only once during the sampling day, however, they did not capture the daily extremes in water quality. Lake level is measured daily by the USGS at three sites around the lake: Rocky Point, Rattlesnake Point, and near the city of Klamath Falls. These daily measurements are then used to compute a spatially weighted average of the lake level that is reported in the USGS annual Water-Data Report for Oregon. The average lake levels were used in this report. Two climatic datasets were used in this report; both were collected at the Klamath Falls airport. Air temperature was recorded as a daily maximum and daily minimum value. Cloud cover was quantized on a daily basis into one of seven levels. Because the focus of this study was primarily to examine possible relations between water quality and lake level, the lake level data provide an important context for the discussions that follow. Close