OCTOBER 2016 MARIN COUNTY STORMWATER POLLUTION PREVENTION PROGRAM AND CITY OF PETALUMA Year 1 Monitoring Report Diazinon and Pesticide-Related Toxicity TMDL Monitoring Program in Urban Creeks submitted to SAN FRANCISCO BAY REGIONAL WATER QUALITY CONTROL BOARD prepared by LARRY WALKER ASSOCIATES ~ This Page Intentionally Left Blank ~ Table of Contents 1. Introduction ........................................................................................................................... 1 2. Monitoring Methods, Stations, and Parameters ................................................................ 2 2.1. Monitoring Stations ........................................................................................................ 2 2.2. Monitoring Events .......................................................................................................... 2 2.3. Monitoring Constituents ................................................................................................. 4 2.4. Stream Flow Analysis ..................................................................................................... 4 2.5. Analytical Methods ......................................................................................................... 5 3. Event Summaries .................................................................................................................. 7 3.1. Event 1: January 5, 2016 ................................................................................................. 7 3.2. Event 2: March 5, 2016 ................................................................................................... 9 3.3. Event 3: June 9, 2016 .................................................................................................... 12 4. Data Summary and Recommendations ............................................................................ 15 4.1. Water Quality Measurements ....................................................................................... 15 4.2. Stage Height and Surface Water Velocity .................................................................... 15 4.3. Conventional Parameters .............................................................................................. 16 4.4. Pesticides....................................................................................................................... 16 4.5. Recommendations for 2016-2017 ................................................................................. 19 Attachments: Attachment A: Applied Marine Sciences Event 1 Field Report, Field Data Sheets, and Chain of Custody Forms Attachment B: Applied Marine Sciences Event 2 Field Report, Field Data Sheets, and Chain of Custody Forms Attachment C: Applied Marine Sciences Event 3 Field Report, Field Data Sheets, and Chain of Custody Forms MCSTOPPP and City of Petaluma i October2016 2015-2016 Urban Creek Monitoring Report List of Tables Table 1. Proposed Pesticide Monitoring Locations ........................................................................ 2 Table 2. Monitoring Constituents .................................................................................................. 4 Table 3. Stream Flow Data Sources ................................................................................................ 5 Table 4. Parameters Monitored in 2015-2016 ................................................................................ 6 Table 5. Event 1 Quality Control Samples ..................................................................................... 7 Table 6. Event 1 Results – January 5, 2016 .................................................................................... 8 Table 7. Event 1 Flow at Marin County Urban Creek Sites – January 5, 2016 .............................. 9 Table 8. Event 2 Quality Control Samples ..................................................................................... 9 Table 9. Event 2 Results – March 5, 2016 .................................................................................... 11 Table 10. Event 2 Flow at Marin County Urban Creek Sites – March 5, 2016 ............................ 12 Table 11. Event 3 Quality Control Samples ................................................................................. 12 Table 12. Event 3 Results – June 9, 2016 ..................................................................................... 13 Table 13. Event 3 Flow at Marin County Urban Creek Sites – June 9th, 2016 ............................. 14 Table 14. General Water Quality Parameters ............................................................................... 15 Table 15. Stage Height and Surface Water Velocity .................................................................... 16 Table 16. Summary Statistics for Pesticide Results in East Marin Creeks and Petaluma River (ng/L) ......................................................................................................................... 17 Table 17. Pesticide Water Quality Thresholds and Comparison with Year 1 Results ................. 18 List of Figures Figure 1. Monitoring Stations and Surrounding Watersheds.......................................................... 3 MCSTOPPP and City of Petaluma ii October2016 2015-2016 Urban Creek Monitoring Report 1. Introduction The Marin County Stormwater Pollution Prevention Program (MCSTOPPP) agencies as well as the City of Petaluma (Petaluma) are subject to the Municipal Separate Stormwater Sewer System (MS4) Phase II General Permit (Phase II Permit).1 MCSTOPPP and Petaluma are conducting regional monitoring efforts to satisfy Phase II Permit monitoring requirements for all MCSTOPPP member agencies and Petaluma. MCSTOPPP consists of the individual cities within Marin County and the unincorporated County areas. MCSTOPPP and Petaluma must comply with the 2005 Diazinon and Pesticide-Related Toxicity in Urban Creeks Total Maximum Daily Load (TMDL) monitoring requirements as described in Attachment G of the Phase II Permit: Monitor water and sediment for pesticides and associated toxicity in urban creeks via an individual or regional program designed to answer the following questions: 1) Are the TMDL toxicity targets being met? Is toxicity observed in urban creeks caused by a pesticide? 2) Is urban runoff the source of any observed toxicity in urban creeks? 3) How does observed pesticide-related toxicity in urban creeks (or pesticide concentrations contributing to such toxicity) vary in time and magnitude across urban creek watersheds, and what types of pest control practices contribute to such toxicity? 4) Are actions already being taken to reduce pesticide discharges sufficient to meet the targets, and if not, what should be done differently? All monitoring activities are conducted in accordance with the August 2015 MCSTOPPP and City of Petaluma Monitoring Plan and Quality Assurance Project Plan: Diazinon and Pesticide- Related Toxicity TMDL Monitoring Program in Urban Creeks (QAPP), unless otherwise noted in this report. The QAPP outlines the management aspects of the monitoring program, the design of the sampling process, the sample collection and handling processes, the analytical methods, the quality control, and the data management, validation, and review. The program aims to characterize pesticide concentrations and other water quality parameters during wet and dry season conditions in East Marin County creeks and the Petaluma River. This report describes the monitoring stations, methods used for sample collection and analysis, field activities conducted during the monitoring events, and the results of field and laboratory measurements produced during sampling season 2015-2016, the first year of a minimum two- year monitoring effort. The report relies on findings gathered by Applied Marine Sciences (AMS), the MCSTOPPP and Petaluma contractor for the sampling project. AMS produced field reports for each monitoring event (see Attachment A through C). 1www.waterboards.ca.gov/water_issues/programs/stormwater/docs/phsii2012_5th/order_final.pdf MCSTOPPP and City of Petaluma 1 October 2016 2015-2016 Urban Creek Monitoring Report 2. Monitoring Methods, Stations, and Parameters Monitoring stations and methods used during the 2015-2016 monitoring program are summarized in this section. Field services in 2015-2016 were provided by AMS for MCSTOPPP while Petaluma used in-house staff. 2.1. MONITORING STATIONS Water quality samples were collected at locations in Novato Creek, San Rafael Creek, Ross Valley, Arroyo Corte Madera del Presidio, and Petaluma River watersheds. The stations are located downstream of urban areas at locations that can be safely accessed during storm runoff events. Along the Petaluma River, samples were also collected at a site upstream of most urban development in the area (PET310). Table 1 shows the monitoring stations and naming conventions. A map of the stations is provided in Figure 1. Characteristics of the tributary watersheds have been previously detailed in the QAPP. Table 1. Proposed Pesticide Monitoring Locations Creek Station Name Location ID Latitude Longitude Novato Creek Lee Gerner Park 206NOV160 38.1070 -122.5786 Arroyo Corte Madera Del Presidio La Goma Bridge 203ACM070 37.8976 -122.5350 Corte Madera Creek Lagunitas Road Bridge 203COR060 37.9632 -122.5571 San Rafael Creek D Street Overcrossing 203SNR180 37.9706 -122.5325 Petaluma River, Upstream Outlet Mall PET310 38.2558 -122.6515 Petaluma River, Downstream 500ft upstream of Ellis Creek