Bon Tempe Photo credit: Barb Stenson 2015 Watershed Sanitary Survey Update Marin Municipal Water District April 2016 K/J 1568032 Prepared by Kennedy/Jenks Consultants 2350 Mission College Blvd., Suite 525 Santa Clara, CA 95054 650-852-2800 FAX: 650-852-2899 Watershed Sanitary Survey Update 2015 Final April 2016 Prepared for Marin Municipal Water District 220 Nellen Avenue Corte Madera, CA 94925 K/J Project No. 1568032 THIS PAGE INTENTIONALLY LEFT BLANK Table of Contents List of Figures ............................................................................................................................... v List of Appendices ........................................................................................................................ vi Section 1: Status of 2010 Watershed Sanitary Survey Recommendations ........................................................................ 1 1.1 Background ............................................................................................ 1 1.2 Status of Recommendations from 2010 WSS ........................................ 1 1.2.1 Sanitary Survey Action Plan (SSAP) .......................................... 2 1.2.1.1 Overall Watershed Recommendations (beneficial to both watersheds): ................................ 2 1.2.1.2 Mount Tamalpais Watershed Recommendations: ................................................... 3 1.2.1.3 Soulajule/Nicasio Watershed Recommendations: ................................................... 3 1.2.2 Watershed Management Practice Investigation ......................... 6 Section 2: Watershed and Supply System .................................................... 9 2.1 MMWD Project Watershed ..................................................................... 9 2.2 Water Supply System ........................................................................... 10 2.2.1 Bon Tempe WTP ...................................................................... 10 2.2.2 San Geronimo WTP ................................................................. 10 2.2.3 Common to both Bon Tempe and San Geronimo WTPs ......... 10 Section 3: Changes to Potential Contaminant Sources ............................. 17 3.1 Update Methods ................................................................................... 17 3.2 Potential Contaminant Sources ............................................................ 17 3.2.1 Septic Tanks ............................................................................. 17 3.2.2 Bon Tempe WTP Sludge Drying .............................................. 18 3.2.3 Reclaimed Water ...................................................................... 18 3.2.4 Urban/Industrial Runoff ............................................................ 19 3.2.4.1 Meadow Club Golf Course ...................................... 19 3.2.4.2 Road/Trail Runoff in Mount Tamalpais Watershed .............................................................. 19 3.2.4.3 Marin County Stormwater Pollution Prevention Program ................................................ 20 3.2.4.4 SWRCB Construction and Industrial Permit Notifications ............................................................ 21 3.2.4.5 Walker Creek TMDL for Mercury ............................ 22 3.2.5 Agricultural Crop Land Use ...................................................... 23 3.2.6 Grazing Animals ....................................................................... 24 2015 Watershed Sanitary Survey Update-FINAL April 2016 Marin Municipal Water District i \\scl\Project\15\1568032.00_ MarinMunicipalWD-2015_Wtrshed_Sanitary_Survey_Update\09-Reports\9.09_Report\Final\2015_MMWD_WSS_combined 040216_clean.docx Table of Contents (cont'd) 3.2.6.1 Tomales Bay Pathogen Total Mass Daily Loading ................................................................... 24 3.2.7 Concentrated Animal Facilities ................................................. 29 3.2.7.1 Dairies ..................................................................... 29 3.2.7.2 Horse Stables ......................................................... 33 3.2.7.3 Conclusions ............................................................ 33 3.2.8 Pesticide/Herbicide Use ........................................................... 33 3.2.8.1 Mount Tamalpais Watershed .................................. 34 3.2.8.2 Soulajule and Nicasio Watersheds ......................... 37 3.2.8.3 Conclusion .............................................................. 37 3.2.9 Wild Animals ............................................................................. 37 3.2.10 Mine Runoff .............................................................................. 38 3.2.11 Solid Waste Management Disposal/Unauthorized Activity ....... 38 3.2.12 Hazardous Materials/Underground Storage Tanks .................. 39 3.2.13 Traffic Accidents/Spills ............................................................. 40 3.2.14 Recreational Use ...................................................................... 40 3.2.15 Logging ..................................................................................... 40 3.2.16 Groundwater Which Influences Surface Water Quality ............ 41 3.2.17 Fires .......................................................................................... 41 3.2.18 Geologic Hazards ..................................................................... 42 3.3 Significance of Potential Contaminant Sources ................................... 42 3.4 Anticipated Growth and Changes within the Study Area ..................... 47 Section 4: Update to Watershed Control And Watershed Management Practices .............................................................. 48 4.1 Watershed Management Practices ...................................................... 48 4.1.1 MMWD Watershed Policies and Program ................................ 48 4.1.2 Land Use Planning and Control ............................................... 49 4.1.2.1 Development Controls in Nicasio Reservoir Watershed. ............................................................. 50 4.1.2.2 Private Landowner Watershed Protection Agreements. ........................................................... 50 4.1.2.3 Agricultural Land Trusts. ......................................... 50 4.1.2.4 On-Site Wastewater Disposal Systems. ................. 50 4.1.3 Land Ownership and Rights-of-Way ........................................ 50 4.1.4 Access Control ......................................................................... 50 4.1.5 Grazing Practices and Wildlife Management ........................... 51 4.1.5.1 Cattle Grazing. ........................................................ 51 4.1.5.2 Wildlife. ................................................................... 52 2015 Watershed Sanitary Survey Update-FINAL April 2016 Marin Municipal Water District ii \\scl\Project\15\1568032.00_ MarinMunicipalWD-2015_Wtrshed_Sanitary_Survey_Update\09-Reports\9.09_Report\Final\2015_MMWD_WSS_combined 040216_clean.docx Table of Contents (cont'd) 4.1.6 Pesticide and Herbicide Applications ....................................... 52 4.1.7 Domestic Animal Use/Control .................................................. 52 4.1.8 Erosion Control/Natural Resource Protection .......................... 53 4.1.9 Road and Trail Maintenance .................................................... 53 4.1.10 Recreation Use ......................................................................... 54 4.1.11 Reservoir Use Restrictions ....................................................... 54 4.1.12 Emergency Response Programs ............................................. 54 4.1.13 Water Quality Monitoring .......................................................... 54 4.1.14 Vegetation Management .......................................................... 54 4.1.15 Wetland Management .............................................................. 55 4.1.16 Public Education and Relations ................................................ 55 4.1.17 Inspection and Surveillance of the Watersheds ....................... 56 4.2 Additional Recommended Watershed Control Measures .................... 56 Section 5: Water Quality .............................................................................. 57 5.1 Overview of Federal and State Drinking Water Requirements ............ 57 5.1.1 Surface Water Treatment Rule ................................................. 59 5.1.2 Interim Enhanced Surface Water Treatment Rule.................... 60 5.1.3 Long Term 2 Enhanced Surface Water Treatment Rule .......... 61 5.1.4 Stage 1 Disinfectants and Disinfection Byproducts Rule ......... 61 5.1.5 Stage 2 Disinfectants and Disinfection Byproducts (DBP) Rule .......................................................................................... 62 5.1.6 Filter Backwash Recycling Rule ............................................... 63 5.1.7 Revised Total Coliform Rule ..................................................... 63 5.2 Water Quality Constituents of Concern ................................................ 63 5.2.1 Constituents with No Significant Regulatory Change Since 2010 ............................................................................... 63 5.2.2 Cryptosporidium and Giardia .................................................... 64 5.2.3 Turbidity .................................................................................... 64 5.2.4 Disinfection Byproducts ...........................................................