San Lorenzo River and North Coast Watersheds Sanitary Survey Update
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Santa Cruz Water Department in association with San Lorenzo Valley Water District San Lorenzo River and North Coast Watersheds Sanitary Survey Update February 2018 This Page Intentionally Blank 2350 Mission College Boulevard, Suite 525 Santa Clara, California 95454 650-852-2800 FAX: 650-856-8527 San Lorenzo River and North Coast Watersheds Sanitary Survey Update February 2018 Prepared for City of Santa Cruz 715 Graham Hill Rd. Santa Cruz, CA 95060 In association with San Lorenzo Valley Water District K/J Project No. 17680004*00 THIS PAGE INTENTIONALLY BLANK Table of Contents List of Tables ................................................................................................................................ ix List of Figures................................................................................................................................ x List of Appendices ........................................................................................................................ xi Preparers ....................................................................................................................................... I Executive Summary ....................................................................................................................... I Section 1: Introduction ............................................................................... 1-1 1.1 Study Area .......................................................................................... 1-1 1.2 Watershed Sanitary Survey Requirements ......................................... 1-1 1.3 Objectives ........................................................................................... 1-3 1.4 Participating Drinking Water Utilities ................................................... 1-3 1.5 Report Organization ............................................................................ 1-3 Section 2: Watersheds and Water Supply Systems ................................... 2-1 2.1 Watershed Description ........................................................................ 2-1 2.1.1 Regional Hydrologic Setting ..................................................... 2-1 2.1.2 Prior Studies............................................................................. 2-2 2.1.3 Significance of Storms, Droughts, Geology, and Baseflow .................................................................................. 2-3 2.2 Land Use and Water Quality ............................................................... 2-5 2.2.1 Land Use .................................................................................. 2-5 2.2.2 Residential ............................................................................... 2-7 2.2.3 Agricultural Uses and Animal Grazing ..................................... 2-8 2.2.4 Timber Harvests ....................................................................... 2-9 2.2.5 Mining..................................................................................... 2-11 2.2.6 Recreation .............................................................................. 2-11 2.2.7 Reservoir Sedimentation ........................................................ 2-12 2.3 Natural Conditions and Water Quality ............................................... 2-12 2.3.1 Soils and Geology .................................................................. 2-13 2.3.2 Faults and Seismic Activity .................................................... 2-15 2.3.3 Volcanic Activity ..................................................................... 2-15 2.3.4 Vegetation .............................................................................. 2-17 2.3.5 Wildlife.................................................................................... 2-17 2.4 Water Supply Systems Background .................................................. 2-18 2.4.1 History .................................................................................... 2-18 2.4.2 Santa Cruz Water Department (SCWD) ................................ 2-21 2.4.3 San Lorenzo Valley Water District (SLVWD) ......................... 2-21 2.5 Water Sources .................................................................................. 2-22 2.5.1 Santa Cruz Water Department ............................................... 2-22 San Lorenzo Valley and North Coast Watersheds Sanitary Survey for SCWD and SLVWD i y:\pw-proj\2017\1768004.00_santacruzwd-watershed sanitary survey\09-reports\9.09-report\feb-18-draft+final\for-022118-final\022118-wss-update.docx Table of Contents (cont’d) 2.5.2 North Coast ............................................................................ 2-22 2.5.3 San Lorenzo River – Intake in Santa Cruz and Tait Wells ..... 2-23 2.5.4 San Lorenzo River - Felton Diversion .................................... 2-23 2.5.5 Loch Lomond Reservoir on Newell Creek .............................. 2-24 2.5.6 SLVWD .................................................................................. 2-24 2.6 Water Rights ..................................................................................... 2-25 2.6.1 SCWD .................................................................................... 2-25 2.6.2 Other Utilities.......................................................................... 2-26 2.6.3 SLVWD .................................................................................. 2-28 2.6.4 Water Quantity ....................................................................... 2-28 2.6.5 Source Management .............................................................. 2-29 2.7 Facilities ............................................................................................ 2-30 2.7.1 Raw Water Reservoirs ........................................................... 2-30 2.7.2 Intakes/Conveyance Systems ................................................ 2-30 2.7.2.1 SCWD .................................................................. 2-32 2.7.2.2 SLVWD ................................................................ 2-32 2.7.3 Treatment Plants/Processes .................................................. 2-32 2.7.3.1 SCWD .................................................................. 2-33 2.7.3.2 SLVWD ................................................................ 2-33 2.7.4 Pipeline Data, Capacity .......................................................... 2-35 2.7.5 Satellite treatment facilities .................................................... 2-37 2.8 Emergency Plans .............................................................................. 2-37 2.8.1 SCWD .................................................................................... 2-37 2.8.2 SLVWD .................................................................................. 2-38 Section 3: POTENTIAL CONTAMINANT SOURCES IN THE WATERSHEDS ............................................................................ 3-1 3.1 Survey Methods .................................................................................. 3-1 3.2 Wastewater ......................................................................................... 3-4 3.2.1 Contaminants of Concern ........................................................ 3-6 3.2.1.1 Bacteria .................................................................. 3-8 3.2.1.2 Nitrate .................................................................... 3-8 3.2.2 San Lorenzo River Watershed ................................................. 3-8 3.2.3 Loch Lomond Reservoir Subwatershed ................................. 3-12 3.2.4 North Coast Watersheds ........................................................ 3-12 3.2.5 Significance ............................................................................ 3-13 3.3 Urban Runoff ..................................................................................... 3-13 3.3.1 Contaminants of Concern ...................................................... 3-15 3.3.2 San Lorenzo River Watershed ............................................... 3-15 3.3.3 Loch Lomond Reservoir and the Upper Newell Creek Watershed ............................................................................. 3-17 3.3.4 North Coast Watersheds ........................................................ 3-17 3.3.5 SLVWD .................................................................................. 3-17 3.3.6 Significance ............................................................................ 3-17 ii San Lorenzo Valley and North Coast Watersheds Sanitary Survey for SCWD and SLVWD Table of Contents (cont’d) 3.4 Agricultural Land Use ........................................................................ 3-18 3.4.1 Contaminants of Concern ...................................................... 3-18 3.4.2 San Lorenzo River Watershed ............................................... 3-18 3.4.3 Loch Lomond Reservoir Subwatershed ................................. 3-19 3.4.4 North Coast Watersheds ........................................................ 3-19 3.4.5 SLVWD .................................................................................. 3-20 3.4.6 Significance ............................................................................ 3-20 3.5 Grazing Livestock .............................................................................. 3-20 3.5.1 Contaminants of Concern ...................................................... 3-21 3.5.2 San Lorenzo Valley ...............................................................