COORDINATED MONITORING PROGRAM FOR GUADALUPE RIVER WATERSHED MERCURY TMDL AGREEMENT NO. A4123A MONITORING PLAN (2018 TO 2023) Prepared for Santa Clara Valley Water District 5750 Almaden Expressway San Jose, CA 95118-3614 Prepared by 3746 Mt. Diablo Blvd., Suite 300 Lafayette, CA 94549 August 3, 2018 TABLE OF CONTENTS 1 Introduction .......................................................................................................................... 1-1 1.1 Project Organization .................................................................................................... 1-2 1.2 Project Definition and Background ............................................................................. 1-2 1.3 Project Objectives and Key Questions ......................................................................... 1-4 1.3.1 Storm Flow Monitoring ........................................................................................... 1-4 1.3.2 Fish Tissue Monitoring in Streams and Lake Almaden........................................... 1-4 2 Storm Threshold Evaluation ................................................................................................ 2-1 2.1 Mobilization Criteria .................................................................................................... 2-7 3 Quality Assurance Project Plan (QAPP) and Sampling and Analysis Plan (SAP).............. 3-1 3.1 Project Tasks ................................................................................................................ 3-1 3.1.1 Storm Flow Monitoring ........................................................................................... 3-1 3.1.2 Permit Acquisition ................................................................................................... 3-1 3.1.3 Fish Tissue Monitoring in Streams and Lake Almaden........................................... 3-2 3.1.4 Reporting and Data Management ............................................................................ 3-2 3.2 QA Measures and Criteria ........................................................................................... 3-2 3.2.1 Quality Objectives and Criteria for Measurement Data .......................................... 3-2 3.3 Sampling Methods ....................................................................................................... 3-4 3.3.1 Survey Locations ..................................................................................................... 3-4 3.3.2 Storm Flow Sampling .............................................................................................. 3-5 3.3.3 Fish Tissue Collection............................................................................................ 3-11 3.4 Sample Documentation and Shipment Procedures .................................................... 3-23 3.4.1 Sample Handling and Custody Requirements ....................................................... 3-24 3.4.2 Packaging Procedures ............................................................................................ 3-24 3.5 Analytical Methods and QA Requirements ............................................................... 3-25 3.5.1 Analytical Methods ................................................................................................ 3-25 3.5.2 Quality Control Requirements ............................................................................... 3-27 3.5.3 Instrument/Equipment Testing, Inspection, and Maintenance Requirements ....... 3-28 3.5.4 Laboratory Quality Control Procedures ................................................................. 3-29 3.5.5 Data Validation and Usability ................................................................................ 3-29 3.6 Training Requirements............................................................................................... 3-30 3.7 Data Acquisition and Management ............................................................................ 3-30 3.7.1 Data Management .................................................................................................. 3-30 Agreement #A4123A QAPP/SAP 3.7.2 Assessments and Response Actions....................................................................... 3-31 3.8 Data Analysis and Reporting ..................................................................................... 3-31 3.8.1 Mercury Loading ................................................................................................... 3-31 3.8.2 Fish Tissue ............................................................................................................. 3-32 4 Project Schedule................................................................................................................... 4-1 5 References ............................................................................................................................ 5-1 Appendix A Field Data Sheets Appendix B Guadalupe Watershed Mercury TMDL Fish Monitoring Plan (SCVWD 2017) Tetra Tech, Inc. Page ii Agreement #A4123A QAPP/SAP LIST OF FIGURES Figure 1-1 Sampling locations within the Guadalupe River watershed. ............................... 1-3 Figure 2-1 Historical instantaneous flows at USGS gage 11169025 above Highway 101. .. 2-3 Figure 2-2 Distribution of peak instantaneous storm flows occurring between 2002 and 2018. .............................................................................................................................. 2-4 Figure 2-3 Distribution of instantaneous base flows during the months of May through September between 2002 and 2018.. ................................................................... 2-6 Figure 2-4 Flow chart for application of mobilization criteria. ........................................... 2-10 Figure 3-1 Duration of rising and falling legs of selected storms relative to peak flow. ...... 3-7 Figure 3-2 Minimum detectable difference, as percent of the mean, relative to sample size between 5 stations for three levels of CV. ......................................................... 3-16 Figure 3-3 Minimum detectable difference, as percent of the mean, relative to sample size between 2 stations (or years) for three CVs. ...................................................... 3-17 Tetra Tech, Inc. Page iii Agreement #A4123A QAPP/SAP LIST OF TABLES Table 2-1 Modeled Instantaneous (15-minute) Peak Flow in Guadalupe River 2-2 Table 2-2 Rainfall Gages in Guadalupe River Watershed 2-7 Table 2-3 Reservoirs in Guadalupe River Watershed 2-8 Table 2-4 Mobilization Criteria 2-9 Table 3-1 Proposed Sampling Locations 3-5 Table 3-2 Results of Regressions of Hydrograph Durations on Peak Flow. 3-8 Table 3-3 Power Analysis for Simulated Annual Sampling1 3-19 Table 3-4 Power Analysis for Simulated Biennial Sampling 3-20 Table 3-5 Planned Analytical Methods for Aqueous and Fish Tissue Samples 3-26 Table 3-6 Quality Control Criteria for Analysis of Parameters in Water 3-27 Tetra Tech, Inc. Page iv 1 INTRODUCTION In 2008, the San Francisco Bay Regional Water Quality Control Board (SFRWQCB) amended the Water Quality Control Plan for the San Francisco Bay Basin (Basin Plan) to establish new water quality objectives, Total Maximum Daily Loads (TMDLs), and an implementation plan to address mercury pollution in the Guadalupe River Watershed1. That amendment imposed surface water, sediment, and fish tissue objectives to restore and protect beneficial uses in waters of the Guadalupe River Watershed and required development of a monitoring program to assess the effectiveness of management actions. The first cycle of monitoring for this TMDL was conducted between 2011 and 2016, and is reported in the Guadalupe River Coordinated Monitoring Program 5-Year Report (AECOM 2017). Sampling was conducted at the USGS gage above Highway 101 to assess mercury loads during the 2014-2015 season. Four storms were sampled: one in December, two in February, and one in April. Depth-integrated, flow weighted suspended samples were collected during each of these storms and were analyzed for total and dissolved mercury, and total and dissolved methylmercury. Age 1 fish were collected from five streams and three reservoirs during 2011, 2012, and 2016. Fish tissue sampling in 2016 was conducted early in the season (May) to correspond with the avian breeding season, whereas fish sampling in 2011 and 2012 was conducted in June in streams and August-September in the reservoirs. The SFRWQCB’s California Water Code Section 13267 letter of 29 June 2017 specifies the required monitoring for the second cycle of monitoring in the Guadalupe river watershed. The required monitoring focuses on collection of fish tissue mercury concentrations to determine spatial and temporal patterns, and on large storm monitoring of suspended sediment and mercury to assess loading to San Francisco Bay. The letter specifies the questions to be resolved, locations to be sampled, and frequency of sampling. The specific monitoring objectives are presented in Section 1.3 of this plan. Sampling methods and procedures are provided in Section 3.3; analytical methods are provided in Section 3.5; and data analysis and reporting are described in Section 3.8. 1 https://www.waterboards.ca.gov/rwqcb2/water_issues/programs/TMDLs/guadaluperivermercurytmdl.html Tetra Tech, Inc. Page 1-1 Agreement #A4123A Monitoring Plan 1.1 PROJECT ORGANIZATION The Santa Clara Valley Water District (District), the County of Santa Clara, Guadalupe Rubbish Disposal Company, and the