Lake Powell Pipeline Project Final Study Report 17 Surface Water Quality April 2016 Table of Contents Executive Summary .................................................................................................................................... 1 Chapter 1 Introduction ............................................................................................................................ 1-1 1.1 Introduction ...................................................................................................................................... 1-1 1.2 Summary Description of LPP Project 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 Alignments ............................................................................................... 1-10 1.2.5 Natural Gas Pipeline and Generators Alternative ................................................................... 1-13 1.3 Summary Description of No Lake Powell Water Alternative ....................................................... 1-18 1.3.1 WCWCD No Lake Powell Water Alternative ........................................................................ 1-19 1.3.2 KCWCD No Lake Powell Water Alternative ......................................................................... 1-23 1.4 Summary Description of the No Action Alternative ...................................................................... 1-23 1.4.1 WCWCD No Action Alternative ............................................................................................ 1-23 1.4.2 KCWCD No Action Alternative ............................................................................................. 1-24 1.5 Study Objectives ............................................................................................................................ 1-24 Chapter 2 Methodology ........................................................................................................................... 2-1 2.1 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 ................................................................................................... 2-2 2.2.3 Significance Criteria ................................................................................................................. 2-2 2.2.4 Impact Assessment .................................................................................................................... 2-2 2.2.5 Mitigation Measures ................................................................................................................. 2-2 Chapter 3 Affected Environment (Baseline Conditions) ...................................................................... 3-1 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 Paria River ................................................................................................................................ 3-8 3.2.3 Virgin River ............................................................................................................................ 3-13 3.3 Beneficial Use Designations - Arizona .......................................................................................... 3-28 3.4 Historical Water Quality Conditions - Arizona ............................................................................. 3-29 3.4.1 Kanab Creek ............................................................................................................................ 3-29 3.4.2 Paria River .............................................................................................................................. 3-29 3.5 Lake Powell ................................................................................................................................... 3-37 3.6 Sand Hollow Reservoir .................................................................................................................. 3-38 Chapter 4 Environmental Consequences (Impacts) ............................................................................. 4-1 4.1 Significance Criteria ........................................................................................................................ 4-1 4.2 LPP Project Alternatives .................................................................................................................. 4-2 4.2.1 Construction Phase .................................................................................................................... 4-2 4.2.2 Operations Phase ....................................................................................................................... 4-5 4.2.3 Water Quality Impacts on Sand Hollow Reservoir ................................................................... 4-7 4.2.4 Water Quality Impacts on Lake Powell and the Lower Colorado River ................................ 4-10 4.2.5 Water Quality Impacts on the Virgin River ............................................................................ 4-14 4.3 No Lake Powell Water Alternative ................................................................................................ 4-14 Lake Powell Pipeline Project i 4/30/16 Final Surface Water Quality Study Report Utah Board of Water Resources 4.4 No Action Alternative .................................................................................................................... 4-15 Chapter 5 Mitigation and Monitoring ................................................................................................... 5-1 5.1 Compliance With NPDES Permitting .............................................................................................. 5-1 5.1.1 Erosion Control ......................................................................................................................... 5-1 5.1.2 Sediment Control ...................................................................................................................... 5-3 5.1.3 Hazardous Material Control ...................................................................................................... 5-4 5.1.4 Final Site Stabilization .............................................................................................................. 5-4 5.2 Compliance Monitoring ................................................................................................................... 5-4 Chapter 6 Unavoidable Adverse Impacts .............................................................................................. 6-1 6.1 Highway Alternative ........................................................................................................................ 6-1 6.2 Existing Highway Alternative .......................................................................................................... 6-1 6.3 Southeast Corner Alternative ........................................................................................................... 6-1 6.4 Transmission Line Alignments ........................................................................................................ 6-1 6.5 Natural Gas Pipeline and Generators Alternative ............................................................................ 6-1 6.6 No Lake Powell Water Alternative .................................................................................................. 6-2 6.7 No Action Alternative ...................................................................................................................... 6-2 Chapter 7 Cumulative Impacts ............................................................................................................... 7-1 7.1 South Alternative ............................................................................................................................. 7-1 7.2 Existing Highway Alternative .......................................................................................................... 7-2 7.3 Southeast Corner Alternative ........................................................................................................... 7-2 7.4 Transmission Line Alignments ........................................................................................................ 7-2 7.5 Natural Gas Pipeline and Generators Alternative ...........................................................................