Suisun Creek Watershed Enhancement Program Summary of Monitoring Results 2002-2010

SUISUN CREEK WATERSHED ENHANCEMENT PROGRAM SUMMARY OF MONITORING RESULTS 2002-2010 Ca. Land Stewardship Institute Laurel Marcus and Associates Dennis Jackson, Hydrologist Hydrologic Systems Inc. Napa County Resource Conservation Service Alison H. Purcell PhD & Matthew R. Cover PhD Aquatic Ecologists California Sportfishing Protection Alliance SUISUN CREEK WATERSHED ENHANCEMENT PROGRAM SUMMARY OF MONITORING RESULTS 2002‐2010 Table of Contents Introduction 1 Background 1 Monitoring Objectives 3 Water Temperature and Water Quality 4 Quality Assurance/Quality Control (QA/QC) 5 Water Quality and Water Temperature Stations 5 Rainfall 8 When is Water too Warm for Steelhead Trout? 10 Sonde Data 11 Suisun Creek Water Temperature and Water Quality Monitoring, Lake Curry Study 14 Suisun Creek 15 Water Temperature Monitoring 15 Water Quality Monitoring 32 Lake Curry 37 Introduction 37 Background 38 Lake Curry Analysis 38 Conclusions 43 Lake Curry Release Experiment 44 Conditions During the Release Experiement 44 Statistical Analysis 58 Does Increasing the Dam Release Make a Difference? 63 Why Isn’t Increasing the Dam Release More Effective? 66 Summary of Suisun Creek Monitoring Data 68 Suisun Creek Fish Survey 70 Fish Survey 71 Methods 71 Results and Discussion 74 Conclusions 85 Suisun Creek Riparian Canopy 86 Introduction 87 Assessment Using Aerial Imagery 87 Water Temperature Station Canopy Surveys 87 Field Survey 93 Wooden Valley Creek Water Temperatures and Water Quality Monitoring 98 Water Temperature Monitoring 98 Water Quality Monitoring 113 Summary of Wooden Valley Creek Monitoring Data 117 White Creek Water Temperature and Water Quality Monitoring 119 Water Temperature Monitoring 120 Water Quality Monitoring 131 Summary of White Creek Monitoring Data 137 Fine Sediment and Streambed Conditions 142 Monitoring Methods and Quality Assurance/Quality Control QA/QC 143 Topographic Surveys 150 Bed Composition 157 Permeability 163 Benthic Macroinvertebrates 167 Introduction 168 Background 168 Methods 171 Results and Discussion 173 Conclusions 178 Attachment 1 180 Attachment 2 184 References 189 Persons Preparing the Report 195 SUISUN CREEK WATERSHED ENHANCEMENT PROGRAM SUMMARY OF MONITORING RESULTS 2002-2010 INTRODUCTION The Suisun Creek watershed encompasses 53 square miles in Napa and Solano counties. The watershed has no urban areas. Three major creeks—White Creek, Wooden Valley Creek, and Suisun Creek—drain a watershed of steep, mountainous terrain and several large valleys into the Suisun Marsh and Suisun Bay (Figure 1). Steelhead trout (Oncorhynchus mykiss), a federally listed threatened species, have been found in the three main creeks of the watershed. The City of Vallejo owns and operates Lake Curry located on the northern end of Suisun Creek. Land use in the watershed is almost entirely rural: cattle grazing and irrigated agriculture consisting of winegrapes, fruit and nut orchards and row crops. A small amount of urban development occurs along Suisun Creek from Rockville Road to Interstate 80. Major roads in the drainage include Suisun Valley Road, Wooden Valley Road, Gordon Valley Road, Highway 121 and Interstate 80. The main creeks in the drainage are primarily open undeveloped channels lined with native vegetation. Table 1 describes the features of each creek. Table 1: Features of Primary Creeks in the Suisun Creek Watershed Creek Length Watershed Area Additional Features White Creek 4.0 miles 6.6 square miles Leona Lakes at headwaters Wooden Valley Creek 6.8 miles 15.2 square miles Drains alluvial Wooden (including White Creek Valley with 3 channels, watershed) then becomes 1 channel through rock gorge Suisun Creek 14 miles (downstream 53 square miles Lake Curry in northern of Lake Curry) area, creek drains wide alluvial Suisun Valley BACKGROUND In 2001 the California Sportfishing Protection Alliance (CSPA) working with Laurel Marcus & Associates (LMA) received a grant from the Ca. State Coastal Conservancy to prepare a watershed assessment and enhancement plan for the Suisun Creek watershed. Water temperature, water quality, and geomorphic monitoring were carried out for the watershed plan between 2001 and 2003. Extensive mapping of riparian forest and field studies of aquatic habitats was also completed. From this assessment the Enhancement Plan identified a number of actions and projects including: Summary of Monitoring Program 2002-2010 – Suisun Creek Watershed Program 1 Figure 1: Suisun Creek Watershed Summary of Monitoring Program 2002-2010 – Suisun Creek Watershed Program 2 • Restoring riparian forest on denuded channel areas to reduce water temperatures • Eradication of invasive species in the riparian corridor to enhance the corridor and reduce water temperatures o Giant Reed (Arundo donax) mapping, eradication strategy and implementation of removal projects o Native riparian revegetation and invasive plant removal projects • Reducing fine sediment in creeks and improving land management measures using: o Farm Conservation Planning program o Community workshops for rural residential landowners • Evaluation of Lake Curry releases to create cold water habitat in Suisun Creek • Continued monitoring to identify additional needed projects In 2004 CSPA, working with LMA, received a grant from the CALFED Watershed Program for implementation of the recommendations of the watershed plan. This grant included a monitoring task for water quality, water temperature, fine sediment, and channel form and project effectiveness monitoring. The grant also funded: • Arundo removal and revegetation on Suisun Creek; • Removal of other invasive plants on all three creeks; • Revegetation in the riparian corridor on all three creeks; • Implementation of the Fish Friendly Farming (FFF) Environmental Certification Program and implementation of FFF projects; • Workshops for rural residents to reduce pollutants; • Development of re-operation alternatives for Lake Curry. This report summarizes the monitoring completed, QA/QC procedures, conclusions drawn from the monitoring and recommendations for additional monitoring and enhancement actions. MONITORING OBJECTIVES The Suisun Creek Watershed Enhancement Program is focused on the improvement of conditions for steelhead trout. For the anadromous life cycle of the steelhead trout to be fulfilled successfully, the freshwater environment must support all steps in this lifecycle - in-migration and spawning of adults, egg incubation and emergence of young, juvenile rearing over the hot summer months and out- migration by juveniles. The freshwater environment, particularly aquatic and riparian (streamside) habitats are created and sustained by watershed and creek processes. For example, spawning habitat requires deposits of gravel within the creek. Gravel is deposited, moved and sifted by both flood events and changes in the natural form of the creek. The gravel needs to be relatively free of fine silt, often a product of excessive erosion in the watershed. If the creek receives few flood events due to reservoirs, or has been straightened and managed as an urban creek, spawning habitat is compromised. Similarly, if erosion from roads and gullies is too great, spawning may occur, but the eggs can be smothered with silt. Similarly, rearing habitat requires adequate cold water to support the small fish. The shade of dense riparian tree cover, deep pools, and cold groundwater help to keep the water below 68 °F when summer air temperatures exceed 100°F. Groundwater availability is a function of the watershed’s ability Summary of Monitoring Program 2002-2010 – Suisun Creek Watershed Program 3 to infiltrate and store rainfall, the geology of the drainage, the condition of the creek, and the extent and timing of water storage and diversions. The ability of the Suisun Creek watershed to support aquatic life results from natural and man-made watershed conditions and processes, as well as whatever direct management is practiced on the creek, its vegetation and floodplain. WATER TEMPERATURE AND WATER QUALITY Continuous water temperature monitoring was carried out from 2002-2010 except for 2004 and 2008 at a series of stations on White, Wooden Valley, and Suisun Creeks. Figure 2 depicts all of the locations used for water temperature and water quality monitoring. The following questions were the focus of the water temperature and water quality monitoring: • How do summer water temperatures change over the length of Suisun Creek as reservoir releases from Lake Curry are varied between 6 cfs and 2 cfs? • How do summer water temperatures vary over the length of Wooden Valley and White Creeks, particularly in relationship to rainfall levels in various years? • How do summer water temperatures vary in Suisun, Wooden Valley and White Creeks according to levels of canopy closure, upstream thermal inputs, width and depth of flow, and other features? • How do dissolved oxygen levels vary in White and Wooden Valley Creeks in summer months and when creeks become intermittent? • How do dissolved oxygen levels compare between Suisun Creek and Wooden Valley Creek over the same time period? • How does dissolved oxygen vary between the upstream portion of Suisun Creek close to the reservoir outlet and downstream 2-3 miles and downstream 5-6 miles? • What is the pH and specific conductance level in each of the tributaries over the summer months and how do levels change with temperature, water depth, and location in the watershed? Two types of monitoring instruments were used: Hobotemp dataloggers for water temperature and

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