Aquatic Vegetation Assessment of Putah Creek, Lake Solano, the Putah South Canal, and the Terminal Reservoir July 2011-June 2013 Prepared for: Solano County Water Agency Prepared by: Emily Peffer University of California, Davis Graduate Group in Ecology Department of Plant Sciences One Shields Avenue, Davis, CA 95616 1 Table of Contents Table of Contents ................................................................................................................................... 2 Executive Summary ................................................................................................................................ 6 1 Introduction ......................................................................................................................................... 9 1.1 Overview ....................................................................................................................................... 9 1.2 The Solano Project ........................................................................................................................ 9 1.3 Problem Statement ...................................................................................................................... 9 1.3.1 Study Goals .......................................................................................................................... 10 1.3.2 Objectives ............................................................................................................................ 11 2 Methods ............................................................................................................................................ 13 2.1 Putah South Canal ...................................................................................................................... 13 2.1.1 Macrophyte and algae sampling ......................................................................................... 13 2.1.2 Sediment and water sampling ............................................................................................. 14 2.1.3 Physical/chemical parameters ............................................................................................ 15 2.2 Terminal Reservoir ..................................................................................................................... 16 2.2.2 Macrophyte and algae sampling ......................................................................................... 16 2.2.3 Sediment and water sampling ............................................................................................. 17 2.2.4 Physical/chemical parameters ............................................................................................ 17 2.3 Lake Solano ................................................................................................................................. 18 2.3.2 Macrophyte and algae sampling ......................................................................................... 19 2.3.3 Sediment and water sampling ............................................................................................. 19 2.3.4 Physical/chemical parameters ............................................................................................ 19 2.4 Putah Creek ................................................................................................................................ 22 2.4.2 Macrophyte sampling .......................................................................................................... 22 2.4.3 Sediment and water sampling ............................................................................................. 22 2 2.4.4 Physical/chemical parameters ............................................................................................ 23 3 Results and Discussion ....................................................................................................................... 24 3.1 Putah South Canal ...................................................................................................................... 24 3.1.1 Algae .................................................................................................................................... 24 3.1.2 Macrophytes ........................................................................................................................ 27 3.1.3 Comparison of 2011 PSC vegetation survey with 2007 survey ........................................... 33 3.1.1 Water samples ..................................................................................................................... 33 3.1.2 Sediment samples ............................................................................................................... 33 3.1.3 Physical/chemical parameters ............................................................................................ 34 3.2 Terminal Reservoir ..................................................................................................................... 37 3.2.1 Plants and Algae .................................................................................................................. 37 3.2.2 Sediment samples ............................................................................................................... 38 3.2.3 Water samples ..................................................................................................................... 39 3.2.4 Physical/chemical parameters ............................................................................................ 39 3.3 Lake Solano ................................................................................................................................. 42 3.3.1 Algae .................................................................................................................................... 42 3.3.2 Macrophytes ........................................................................................................................ 42 3.3.3 Sediment .............................................................................................................................. 48 3.3.4 Water samples ..................................................................................................................... 55 3.3.5 Physical/chemical parameters ............................................................................................ 56 3.3.6 Year-long temperature data ................................................................................................ 68 3.3.1 Light ..................................................................................................................................... 70 3.4 Putah Creek (IDR) ....................................................................................................................... 72 3.4.1 Macrophytes ........................................................................................................................ 72 3.4.2 Sediment .............................................................................................................................. 75 3.4.3 Water samples ..................................................................................................................... 78 3 3.4.4 Physical/chemical parameters ............................................................................................ 78 4 Data Modeling ................................................................................................................................... 81 4.1 Modeling approach .................................................................................................................... 81 4.2 Modeling results ......................................................................................................................... 84 4.3 Model performance.................................................................................................................... 94 5 Recommendations for Management ................................................................................................ 97 5.1 Interdam Reach .......................................................................................................................... 97 5.1.1 Direct removal or reduction of macrophytes in the IDR ..................................................... 97 5.1.2 Scouring flows ..................................................................................................................... 98 5.1.3 Increasing the depth of Lake Solano ................................................................................... 99 5.1.4 Shading macrophytes with benthic barriers ..................................................................... 100 5.1.5 Converting wide, shallow areas of Lake Solano to marsh or floodplain ........................... 100 5.2 Putah South Canal and Terminal Reservoir .............................................................................. 102 5.2.1 Scouring flows ................................................................................................................... 102 5.2.2 Physical dislodging of macrophytes .................................................................................. 102 5.2.3 Repairing, sealing, or covering cracks and seams in the PSC ............................................ 102 5.2.4 Reducing sediment input from upstream sources ............................................................ 102 5.2.5 Improving canal