Assessment of Water Quality, Road Runoff, and Bulk Atmospheric Deposition, Guanella Pass Area, Clear Creek and Park Counties, Colorado, Water Years 1995–97 By Michael R. Stevens U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 00–4186 Prepared in cooperation with the FEDERAL HIGHWAY ADMINISTRATION and CLEAR CREEK COUNTY Denver, Colorado 2001 U.S. DEPARTMENT OF THE INTERIOR GALE A. NORTON, Secretary U.S. GEOLOGICAL SURVEY Charles G. Groat, Director The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey. For additional information write to: Copies of this report can be purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Information Services Box 25046, Mail Stop 415 Box 25286 Denver Federal Center Federal Center Denver, CO 80225–0046 Denver, CO 80225 CONTENTS Abstract.................................................................................................................................................................................. 1 Introduction............................................................................................................................................................................ 3 Purpose and Scope....................................................................................................................................................... 3 Acknowledgments ....................................................................................................................................................... 3 Description of Study Area ..................................................................................................................................................... 3 Monitoring Network and Quality Assurance......................................................................................................................... 5 Characterization of Water Resources..................................................................................................................................... 12 Precipitation................................................................................................................................................................. 12 Streams ........................................................................................................................................................................ 13 Hydrology .......................................................................................................................................................... 13 Water-Quality Characteristics............................................................................................................................ 15 Onsite Measurements............................................................................................................................... 16 Dissolved-Solids Loads ........................................................................................................................... 22 Major Ions................................................................................................................................................ 23 Possible Effects of Magnesium Chloride Applications on Major-Ion Chemistry in Streams ................. 26 Nutrients .................................................................................................................................................. 36 Trace Elements ........................................................................................................................................ 41 Suspended Sediment, Turbidity, and Streambed-Particle Size................................................................ 46 Basin Characteristics of Suspended-Sediment Sites...................................................................... 46 Suspended-Sediment Concentrations and Loads........................................................................... 48 Comparison-Site Suspended-Sediment Yields .............................................................................. 50 Sediment Discharge by Hydrograph Period .................................................................................. 51 Turbidity ........................................................................................................................................ 52 Peak Suspended Sediment and Turbidity During Storms.............................................................. 53 Bed-Material Particle Size............................................................................................................. 54 Storm-Runoff Effects on Stream-Water Quality...................................................................................... 55 Lakes and Reservoirs ................................................................................................................................................... 64 Vertical Profiles and Onsite Measurements....................................................................................................... 64 Transparency and Chlorophyll........................................................................................................................... 67 Water-Column Major Ions, Nutrients, and Trace Elements............................................................................... 67 Nutrient Limitation and Trophic Status ............................................................................................................. 69 Bottom-Sediment Chemistry ............................................................................................................................. 69 Ground Water............................................................................................................................................................... 71 Onsite Measurements and Major Ions ............................................................................................................... 71 Nutrients ............................................................................................................................................................ 74 Trace Elements .................................................................................................................................................. 74 Comparisons with Water-Quality Standards................................................................................................................ 74 Streams .............................................................................................................................................................. 74 Colorado Water-Quality Standards.......................................................................................................... 74 Other Guidelines...................................................................................................................................... 79 Ground Water..................................................................................................................................................... 80 Characterization of Guanella Pass Road Runoff ................................................................................................................... 81 Background Information on Forest Road Hydrology.................................................................................................. 81 Hydrology .................................................................................................................................................................... 83 Water-Quality Characteristics...................................................................................................................................... 84 Onsite Measurements and Major Ions ............................................................................................................... 84 Nutrients ............................................................................................................................................................ 86 Trace Elements .................................................................................................................................................. 87 Organic Carbon and Trace-Organic Constituents.............................................................................................. 87 Suspended Sediment and Particle Size .............................................................................................................. 87 Sources and Transport of Sediment in Road Runoff ................................................................................................... 87 CONTENTS III Sources and Deposits of Sediment .................................................................................................................... 87 Road Drainage and Stream Linkage.................................................................................................................. 93 Seasonal Characteristics of Sediment and Dissolved Solids in Road Runoff ................................................... 102 Sediment.................................................................................................................................................. 104 Dissolved Solids ...................................................................................................................................... 106 Potential Effects of Road