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U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2007–5117

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

Prepared in cooperation with the Bureau of Reclamation

By Jennifer L. Morace

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Table of Contents

Conversion Factors, Datums, and Abbreviations and Acronyms

Abstract

Introduction

Description of Datasets and Methods

Characterization of Years

Temporal and Spatial Variability of Poor Water-Quality Conditions

Hypotheses Relating Water Quality to Lake Level and Climate

Information-Theoretic Approach to Multivariable Analysis of Water-Quality Conditions

Data Caveats and Future Directions

Summary

Acknowledgments

References Cited

Figures

Figure 1. Sites on Upper Klamath and Agency Lakes, Oregon, with 10 or more years of water-quality data, 1990–2006.

Figure 2. Daily lake level of Upper Klamath Lake, Oregon, 1990–2006.

Figure 3. Comparison of May through August end-of-month lake level for 1990–2006 with the frequency distribution of the historical, post-dam, end-of-month values for 1922–2006, Upper Klamath Lake, Oregon.

Figure 4. Median lakewide chlorophyll-a concentrations, Upper Klamath Lake, Oregon, 1997.

Figure 5. Depth-profile pH data, Upper Klamath and Agency Lakes, Oregon, June–October 2000.

Figure 6. Water-quality conditions in 2000, Upper Klamath and Agency Lakes, Oregon.

Figure 7. Median chlorophyll-a concentrations, May–October 1990–2006, Upper Klamath Lake, Oregon.

Figure 8. Frequency distributions of lakewide chlorophyll-a data, by month, Upper Klamath and Agency Lakes, Oregon, June–September 1990–2006.

Figure 9. Relation of median June chlorophyll-a concentration to median June lake level and cumulative degree-days from April 1 to May 15, Upper Klamath and Agency Lakes, Oregon, 1990–2006

Figure 10. Relation of the timing of the onset of the bloom to the median June lake level and cumulative degree-days between April 1 and May 15, Upper Klamath Lake, Oregon, 1990–2006.

Figure 11. Daily maximum pH values measured at Wocus Bay, May–October 1990–2006, Upper Klamath Lake, Oregon.

Figure 12. Frequency distribution of lakewide pH data, by month, Upper Klamath and Agency Lakes, Oregon, June–September 1990–2006.

Figure 13. Daily maximum observed pH values at each site for June–September 1990–2006, Upper Klamath Lake and Agency Lakes, Oregon.

Figure 14. Frequency distribution of June lakewide pH data displayed by lake level, cumulative degree-days, and timing of the bloom onset, Upper Klamath and Agency Lakes, Oregon, 1990–2006.

Figure 15. Frequency distribution of lakewide dissolved-oxygen data, by month, Upper Klamath and Agency Lakes, Oregon, June–September 1990–2006.

Figure 16. Daily minimum observed dissolved-oxygen concentrations at each site for June–September, Upper Klamath Lake and Agency Lakes, Oregon, 1990–2006.

Figure 17. Frequency distribution of July lakewide dissolved-oxygen data displayed by lake level, cumulative degree-days, and timing of the bloom onset, Upper Klamath and Agency Lakes, Oregon, 1990–2006.

Figure 18. Depth-profile dissolved-oxygen data at Eagle Ridge for 4 years, Upper Klamath Lake, Oregon.

Figure 19. Frequency distribution of lakewide total-phosphorus data, by month, Upper Klamath and Agency Lakes, Oregon, June–October 1990–2006.

Figure 20. Relation of lakewide median chlorophyll-a concentration to lakewide median total-phosphorus concentration, Upper Klamath Lake, Oregon, June 1990–2006.

Figure 21. Relation of lakewide median chlorophyll-a concentration to lakewide median total phosphorus concentration, by area, Upper Klamath and Agency Lakes, Oregon, June 1990–2006.

Figure 22. Lakewide median surface water temperature, Upper Klamath Lake, Oregon, May–October 1990–2006.

Figure 23. Lakewide median surface water temperatures for 2000, 2001, and 2006, Upper Klamath Lake, Oregon.

Tables

Table 1. Numbers of sampling dates that depth-profile measurements were recorded and composite samples were collected, Upper Klamath and Agency Lakes, Oregon , May–October 1990–2006.

Table 2. Ranking of percentiles of lake level by month for May–August 1990–2006 based on post-dam 1922–2006 end-of-month lake level and overall ranking of years, Upper Klamath Lake, Oregon.

Table 3. Ranking of years from warmest to coolest spring based on cumulative degree-days from April 1 to May 15, Upper Klamath Lake, Oregon, 1990–2006.

Table 4. Ranking of years based on the timing of the onset of the Aphanizomenon flos-aquae bloom, Upper Klamath Lake, Oregon, 1990–2006.

Table 5. Comparison of ranking of years based on wind-speed data measured at the Klamath Falls airport and at the Agrimet site adjacent to Agency Lake, Oregon, July–August 2000–2006.

Table 6. Ranking of 1990–2006 by lake level, degree-days, and timing of bloom onset, Upper Klamath Lake, Oregon.

Table 7. Summary of dissolved-oxygen concentrations in the depth-profile dataset, Upper Klamath and Agency Lakes, Oregon, May–October 1990–2006.

Table 8. Percentage of dissolved-oxygen concentrations in the depth-profile dataset less than 4 milligrams per liter by year and site, Upper Klamath and Agency Lakes, Oregon, May–October 1990–2006.

Table 9. Summary of pH values in the depth-profile dataset, Upper Klamath and Agency Lakes, Oregon, May–October 1990–2006.

Table 10. Percentage of pH values in the depth-profile dataset greater than 9.7 by year and site, Upper Klamath and Agency Lakes, Oregon, May–October 1990–2006.

Table 11. Number of samples exceeding the acute and chronic total-ammonia guidelines by year and site, Upper Klamath and Agency Lakes, Oregon, 1990–2006.

Table 12. Number of un-ionized ammonia concentrations exceeding 530 micrograms per liter by year and site, Upper Klamath and Agency Lakes, Oregon, 1990–2006.

Table 13. Ranking of years 1990–2006 by lake level, degree-days, and timing of bloom onset shaded to illustrate the relation between water temperature and lake level, Upper Klamath Lake, Oregon.

Table 14. Akaike weights and supporting variables for evaluating the percentage of dissolved-oxygen concentrations less than 4 milligrams per liter, Upper Klamath and Agency Lakes, Oregon, 1990–2006.

Table 15. Akaike weights and supporting variables for evaluating the percentage of pH values greater than 9.7, Upper Klamath and Agency Lakes, Oregon, 1990–2006.

Table 16. Akaike weights and supporting variables for evaluating the minimum July–August dissolved-oxygen concentration at Midnorth, Upper Klamath Lake, Oregon, 1990–2006.

Table 17. Akaike weights and supporting variables for evaluating models of water temperature and a second physical variable in relation to minimum July–August dissolved-oxygen concentration at Midnorth, Upper Klamath Lake, Oregon, 1990–2006.

Table 18. Akaike weights and supporting variables for evaluating models of lake level in relation to minimum July–August dissolved-oxygen concentration at Midnorth, Upper Klamath Lake, Oregon, 1990–2006.

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Send questions or comments about this report to the author, J.L. Morace, (503) 251-3229.

For more information about USGS activities in Oregon, visit the USGS USGS Oregon Water Science Center home page.