Lake Powell Pipeline Draft Study Report 17 Surface Water Quality March 2010 Lake Powell Pipeline 3/10/11 Draft Surface Water Quality Study Report Utah Board of Water Resources Table of Contents Page Executive Summary ES-1 Introduction ...................................................................................................................... ES-1 ES-2 Methodology .................................................................................................................... ES-1 ES-3 Key Results of the Wetlands and Riparian Resources Impact Analyses ......................... ES-1 ES-3.1 LPP Project Alternative ................................................................................... ES-1 ES-3.2 No Lake Powell Water Alternative .................................................................. ES-2 ES-3.3 No Action Alternative ...................................................................................... ES-2 Section 1 Introduction 1.1 Introduction ......................................................................................................................... 1-1 1.2 Summary Description of Alignment Alternatives ............................................................... 1-1 1.2.1 South Alternative ................................................................................................ 1-1 1.2.2 Existing Highway Alternative ............................................................................ 1-8 1.2.3 Southeast Corner Alternative .............................................................................. 1-8 1.2.4 Transmission Line Alternatives ........................................................................ 1-10 1.3 Summary Description of No Lake Powell Water Alternatives ......................................... 1-17 1.3.1 WCWCD No Lake Powell Water Alternative .................................................. 1-17 1.3.2 CICWCD No Lake Powell Water Alternative .................................................. 1-18 1.3.3 KCWCD No Lake Powell Water Alternative ................................................... 1-18 1.4 Summary Description of the No Action Alternative ......................................................... 1-18 1.4.1 WCWCD No Action Alternative ...................................................................... 1-19 1.4.2 CICWCD No Action Alternative ...................................................................... 1-19 1.4.3 KCWCD No Action Alternative ....................................................................... 1-19 1.5 Objectives of the Study ..................................................................................................... 1-20 Section 2 – Methodology 2.2 Data Sources ....................................................................................................................... 2-1 2.2 Evaluation Methodology ..................................................................................................... 2-1 2.2.1 Beneficial uses and Water Quality Criteria ........................................................ 2-1 2.2.2 Historical Water Quality Data ............................................................................ 2-1 2.2.3 Significant Criteria .............................................................................................. 2-2 2.2.4 Impact Assessment ............................................................................................. 2-2 2.2.5 Mitigation Measures ........................................................................................... 2-2 Section 3 – Affected Environment (Baseline Conditions) 3.1 Beneficial Use Designations – Utah ................................................................................... 3-1 3.2 Historical Water Quality Conditions – Utah ....................................................................... 3-2 3.2.1 Kanab Creek ....................................................................................................... 3-3 3.2.2 Ash Creek ........................................................................................................... 3-4 3.2.3 Mill Creek ........................................................................................................... 3-5 3.2.4 LaVerkin Creek................................................................................................. 3-11 3.2.5 Paria River ........................................................................................................ 3-11 3.2.6 Virgin River ...................................................................................................... 3-18 3.3 Beneficial Use Designations – Arizona ............................................................................ 3-29 3.4 Historical Water Quality Conditions – Arizona ................................................................ 3-29 3.4.1 Kanab Creek ..................................................................................................... 3-30 Lake Powell Pipeline TOC-i 3/10/11 Draft Surface Water Quality Resources Study Report Utah Board of Water Resources Table of Contents (continued) 3.4.2 Paria River ........................................................................................................ 3-30 3.5 Lake Powell ....................................................................................................................... 3-37 3.6 Sand Hollow Reservoir ..................................................................................................... 3-38 Section 4 – Environmental Consequences (Impacts) 4.1 Significance Criteria............................................................................................................ 4-1 4.2 Alignment Alternatives ....................................................................................................... 4-1 4.2.1 Construction Phase ............................................................................................. 4-2 4.2.1.1 Clearing and Grading ......................................................................... 4-2 4.2.1.2 Open-Cut Crossings ............................................................................ 4-2 4.2.1.3 Trenchless Construction Techniques .................................................. 4-3 4.2.1.4 Summary of Construction Impacts ..................................................... 4-4 4.2.2 Operations Phase................................................................................................. 4-4 4.2.2.1 Maintenance Pipeline Discharges ....................................................... 4-5 4.2.2.1.1 Pipeline Flushing ................................................................ 4-6 4.2.2.1.2 Drain Valves ....................................................................... 4-6 4.2.2.1.3 Pigging ............................................................................... 4-6 4.2.2.2 Pipeline Rupture ................................................................................. 4-6 4.2.2.3 Quagga Mussel Control Program ....................................................... 4-7 4.2.3 Water Quality Impacts on Sand Hollow Reservoir ............................................. 4-7 4.2.3.1 Inflows ................................................................................................ 4-7 4.2.3.2 Outflows ............................................................................................. 4-9 4.2.3.3 Model Results ..................................................................................... 4-9 4.2.4 Water Quality Impacts on Lake Powell and the Lower Colorado River .......... 4-10 4.2.4.1 Lake Powell ...................................................................................... 4-11 4.2.4.2 Glen Canyon Dam Release ............................................................... 4-11 4.2.4.3 Lower Colorado River – Salinity ...................................................... 4-12 4.2.4.4 Summary of Operations Phase Impacts ............................................ 4-12 4.2.5 Water Quality Impacts on the Virgin River ...................................................... 4-13 4.3 No Lake Powell Water Alternative ................................................................................... 4-14 4.4 No Action Alternative ....................................................................................................... 4-14 Section 5 – Mitigation Monitoring 5.1 Compliance With NPDES Permitting ................................................................................. 5-1 5.1.1 Erosion Control ................................................................................................... 5-1 5.1.1.1 Preservation of Existing Vegetation ................................................... 5-2 5.1.1.2 Soil Binders ........................................................................................ 5-2 5.1.1.4 Runoff Interception and Diversion ..................................................... 5-2 5.1.1.5 Dust Control ....................................................................................... 5-3 5.1.2 Sediment Control ................................................................................................ 5-3 5.1.2.1 Silt Fence and Sandbag Barriers ......................................................... 5-3 5.1.2.2 Sediment Basin ................................................................................... 5-3 5.1.3 Hazardous Material Control ...............................................................................