Front cover: Top: The Santiam River at river mile 9.5, taken on August 7, 2002. Lower: The North Santiam River at river mile 57.3, taken on June 4, 2002. Both photographs by Ian Wigger (U.S. Geological Survey). Modeling Streamflow and Water Temperature in the North Santiam and Santiam Rivers, Oregon, 2001–02 By Annett B. Sullivan and Stewart A. Rounds Prepared in cooperation with the Oregon Association of Clean Water Agencies Scientific Investigations Report 2004–5001 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior Gale A. Norton, Secretary U.S. Geological Survey Charles G. Groat, Director U.S. Geological Survey, Portland, Oregon: 2004 For sale by U.S. Geological Survey, Information Services Box 25286, Denver Federal Center Denver, CO 80225 For more information about the USGS and its products: Telephone: 1-888-ASK-USGS World Wide Web: http://www.usgs.gov/ Any use of trade, product, or firm names in this publication 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 materials contained within this report. The calibrated models of the North Santiam and Santiam Rivers, as used in this investigation, are available for download from the Internet at http://oregon.usgs.gov/projs_dir/will_tmdl/model.html Suggested citation: Sullivan, A.B., and Rounds, S.A., 2004, Modeling streamflow and water temperature in the North Santiam and Santiam Rivers, Oregon, 2001–02: U.S. Geological Survey Scientific Investigations Report 2004–5001, 35 p. iii CONTENTS Abstract . .1 Significant Findings . .1 Introduction . .2 Site Description, Basin Characteristics, and Hydrology . .2 Purpose and Scope. .4 Methods . .4 Model Description. .4 Bathymetric Data and the Model Grid. .5 Temporal Inputs and Shading . .5 Meteorology . .6 Precipitation . .6 Streamflow and Stream Temperature. .6 Withdrawals . .8 Riparian Shading . .8 Ground Water and Ungaged Tributaries. .10 Calibration Data. .10 Model Calibration . .11 Water Balance. .11 Flow. .11 Channel Width. .12 Travel Times . .12 Water Temperature. .14 Sensitivity Analysis . .22 Point Sources. .23 Dam Release Temperature . .23 Air Temperature. .24 Riparian Vegetation. .24 Dam Release Flow. .26 Simulation of System Potential Conditions. .27 System-Potential Vegetation with Proposed NOAA Fisheries Target Flows . .27 System-Potential Vegetation with Proposed NOAA Fisheries Target Flows and a More Natural Seasonal Temperature Regime in Dam Releases . .27 Summary. .29 Acknowledgments . .30 References Cited. .30 Appendix 1. Revised Water Temperature Standards . .35 iv Figures 1. Map of the North Santiam and Santiam rivers, Oregon, showing the locations of data-collection stations . 3 2. Schematic diagram of the model grid, with branch boundaries and river miles from the mouth of the Santiam River . .6 3. Schematic diagram showing locations of point-source and tributary inflows, withdrawals, and USGS streamflow gages . ..