NUTRIENT MANAGEMENT PLAN LIVERMORE VALLEY GROUNDWATER BASIN July 2015 PREPARED BY: ZONE 7 WATER AGENCY 100 North Canyons Parkway Livermore, CA 94551 (925) 454-5000 PREPARED BY: ZONE 7 WATER AGENCY STAFF Matt Katen, P.G. – Principal Geologist Tom Rooze, P.G. – Associate Geologist Contributors: Jill Duerig, P.E. – General Manager Kurt Arends, P.E. – Assistant General Manager Jarnail Chahal, P.E. – Engineering Manager Colleen Winey, P.G. – Assistant Geologist Table of Contents Page ES Executive Summary ...................................................................................................................................i ES 1 Background ..................................................................................................................................................i ES 2 Groundwater Basin Characteristics and Nitrate Concentrations .............................................................. ii ES 3 Nutrient Loading Evaluation...................................................................................................................... ii ES 4 Antidegradation Analysis ........................................................................................................................... iv ES 5 Nutrient Management Goals and Strategies ............................................................................................... v ES 6 Plan Implementation ................................................................................................................................. vii 1 Background ............................................................................................................................................... 1 1.1 Introduction ................................................................................................................................................. 1 1.2 Purpose and Management Objectives ......................................................................................................... 2 1.3 Regulatory Framework ............................................................................................................................... 3 1.3.1 Master Water Recycling Permit and Salt Management Plan ...................................................... 3 1.3.2 State Recycled Water Policy ...................................................................................................... 3 1.3.3 Onsite Wastewater Treatment Systems (OWTS) ....................................................................... 4 1.3.4 Zone 7 Wastewater Management Plan ....................................................................................... 4 1.3.5 Groundwater Management Plan and Annual Reports ................................................................ 5 1.4 Stakeholder Involvement ............................................................................................................................. 5 1.5 CEQA Considerations ................................................................................................................................. 6 2 Basin Characteristics and Nitrate Concentrations ................................................................................. 9 2.1 Groundwater Basin Overview ..................................................................................................................... 9 2.1.1 Geology .................................................................................................................................... 10 2.1.2 Main and Fringe Basins ............................................................................................................ 11 2.1.3 Aquifer Zones ........................................................................................................................... 11 2.1.4 Land Use .................................................................................................................................. 15 2.2 Groundwater Inventory ............................................................................................................................. 16 2.2.1 Conjunctive Use ....................................................................................................................... 16 2.2.2 Groundwater Storage ................................................................................................................ 16 2.2.3 Groundwater Production .......................................................................................................... 16 2.2.4 Groundwater Sustainability ...................................................................................................... 17 Nutrient Management Plan July 2015 I 2.3 Basin Water Quality (Nutrients) ............................................................................................................... 19 2.3.1 Overview .................................................................................................................................. 19 2.3.2 Nitrate Concentrations .............................................................................................................. 20 2.3.3 Assimilative Capacity ............................................................................................................... 26 2.4 Areas of Concern ...................................................................................................................................... 26 3 Nutrient Loading Evaluation ................................................................................................................. 35 3.1 Historical Sources of Nitrate .................................................................................................................... 35 3.2 Conceptual Model ..................................................................................................................................... 36 3.2.1 Fate and Transport of Nitrate .................................................................................................... 36 3.2.2 Methodology ............................................................................................................................ 37 3.3 Nitrogen Loading Calculations ................................................................................................................. 41 3.3.1 Current Nitrogen Loading ........................................................................................................ 41 3.3.2 Future Nitrate Loading ............................................................................................................. 46 3.4 Projected Nitrate Concentrations ............................................................................................................. 51 4 Proposed Projects and Antidegradation Analysis ................................................................................ 55 4.1 Recycled Water Projects ........................................................................................................................... 55 4.2 Stormwater Capture Projects .................................................................................................................... 56 4.3 State Water Board Recycled Water Policy Criteria .................................................................................. 56 4.4 Antidegradation Assessment ..................................................................................................................... 57 5 Nutrient Management Goals and Strategies ......................................................................................... 59 5.1 Introduction ............................................................................................................................................... 59 5.2 Investigate Areas of Concern .................................................................................................................... 59 5.3 Minimize Nitrogen Loading ...................................................................................................................... 59 5.3.1 Introduction .............................................................................................................................. 59 5.3.2 Fertilizer Application................................................................................................................ 60 5.3.3 Recycled Water Irrigation ........................................................................................................ 60 5.3.4 Livestock Manure Management ............................................................................................... 60 5.3.5 Onsite Wastewater Treatment Systems .................................................................................... 61 5.4 Enhanced Attenuation ............................................................................................................................... 62 6 Plan Implementation ............................................................................................................................... 63 6.1 Investigate Boundaries of Areas of Concern ............................................................................................. 63 6.2 Implementation Measures to Minimize Nitrogen Loading ........................................................................ 63 6.2.1 Introduction .............................................................................................................................. 63 6.2.2 Fertilizer