Prepared in cooperation with Douglas County and the U.S. Forest Service Water Quality and Algal Conditions in the North Umpqua River, Oregon, 1995–2007, and their Response to Diamond Lake Restoration This Open-File Report 2014-1098 U.S. Department of the Interior U.S. Geological Survey Cover: Clockwise from upper left — (1) Upper North Umpqua River at Inlet Campground, (2) Diamond Lake with Mt. Thielsen in the background, (3) Wild and Scenic River reach downstream from Copeland Creek, (4) middle North Umpqua River downstream of Lemolo Lake. (Photographs 1, 3, and 4 by Kurt Carpenter, U.S. Geological Survey; photograph 2 by Mikeal Jones, U.S. Forest Service, ret.) Water Quality and Algal Conditions in the North Umpqua River, Oregon, 1995–2007, and their Response to Diamond Lake Restoration By Kurt D. Carpenter, Chauncey W. Anderson, and Mikeal E. Jones Prepared in cooperation with Douglas County and the U.S. Forest Service Open-File Report 2014–1098 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior SALLY JEWELL, Secretary U.S. Geological Survey Suzette M. Kimball, Acting Director U.S. Geological Survey, Reston, Virginia 2014 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod To order this and other USGS information products, visit http://store.usgs.gov Suggested citation: Carpenter, K.D., Anderson, C.W., and Jones, M.E., 2014, Water quality and algal conditions in the North Umpqua River, Oregon, 1995–2007, and their response to Diamond Lake restoration: U.S. Geological Survey Open-File Report 2014-1098, 89 p. http://dx.doi.org/10.3133/ofr20141098. ISSN 2331-1258 (online) Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted material contained within this report. Contents Summary ....................................................................................................................................................................... 1 Introduction .................................................................................................................................................................... 4 Study Background ...................................................................................................................................................... 4 Study Objectives, Approach, and Report Scope ........................................................................................................ 8 Study Area ................................................................................................................................................................. 9 Wild and Scenic River Reach ................................................................................................................................11 Hydroelectric Project .............................................................................................................................................12 Diamond and Lemolo Lakes ..................................................................................................................................13 Methods ........................................................................................................................................................................14 Data Collection ..........................................................................................................................................................14 Water-Quality Samples and Field Measurements .................................................................................................16 Continuous Water-Quality Monitors .......................................................................................................................20 Streamflow ............................................................................................................................................................20 Algal Samples and Laboratory Analysis ................................................................................................................20 Data Analysis ............................................................................................................................................................21 Water Chemistry ....................................................................................................................................................21 Algae .....................................................................................................................................................................24 Quality-Assurance Data ............................................................................................................................................26 Nutrients ................................................................................................................................................................26 Algae .....................................................................................................................................................................26 Hydrologic, Water-Quality, and Benthic-Algae Conditions, 1995–2007 ........................................................................27 Hydrologic Conditions ...............................................................................................................................................27 Patterns in Hydrology in 1995–2007 and Changes Associated with the New Hydroelectric License ....................27 Changes in Hydrology Associated with the Diamond Lake Restoration Project ....................................................32 Water-Quality Conditions ..........................................................................................................................................33 Field Parameters—Water Temperature, Dissolved Oxygen, pH, and Turbidity .....................................................33 Lake Creek and the Diamond Lake Drawdown .....................................................................................................41 Nutrients and Organic Carbon ...............................................................................................................................44 Diamond Lake, 2006–07 .......................................................................................................................................44 Monthly Sampling in Lake Creek and the North Umpqua River, 2006–07 .............................................................44 Comparison of Nutrient Concentrations and Algal Biomass to Suggested Criteria................................................50 Changes in Water-Quality Conditions between 1995 and 2005–07 ......................................................................50 Benthic Algal Conditions ...........................................................................................................................................56 Periphyton Biomass ..............................................................................................................................................56 Periphyton Species Composition ...........................................................................................................................58 Periphyton Guilds ..................................................................................................................................................61 Changes in Algal Species Composition between 1995 and 2005 .........................................................................64 Changes in Algal Species Composition between 2005 and 2007 .........................................................................66 Algal Conditions at Selected Sites from 1995 to 2005–07 .....................................................................................68 Factors Shaping Periphyton Assemblages: Results of Multivariate BEST Analyses .............................................70 Discussion ....................................................................................................................................................................72 Effects of the Diamond Lake Restoration Project on Lake Creek and the North Umpqua River ...............................72 Streamflow, Water Quality, and Algal Conditions between Synoptic Surveys ...........................................................73 Potential Effects of Resource Management on Water Quality and Algal Conditions .................................................76 Suggestions for Future Monitoring and Studies ........................................................................................................77 iii Conclusions ..................................................................................................................................................................80 Acknowledgements.......................................................................................................................................................82 References Cited ..........................................................................................................................................................82