David Magney Environmental Consulting CALLEGUAS CREEK WATERSHED WETLAND RESTORATION PLAN Prepared for: CALIFORNIA STATE COASTAL CONSERVANCY AND U.S. ENVIRONMENTAL PROTECTION AGENCY October 2000 David Magney Environmental Consulting Calleguas Creek Watershed Wetland Restoration Plan Prepared for: California State Coastal Conservancy 1330 Broadway, Suite 1100 Oakland, California 94612 Contact: Peter Brand 510/286-4162 and U.S. Environmental Protection Agency 75 Hawthorne Street, Mail Code: W-3-2 San Francisco, CA 94105 Contact: Paul Michel 415/744-1999 Prepared by: David Magney Environmental Consulting P.O. Box 1346 Ojai, California 93024-1346 Contact: David L. Magney 805/646-6045 with: Geo InSight International, Inc. SECOR International Incorporated, and Wildlands, Inc. October 2000 This report has been funded wholly or in part by the United States Environmental Protection Agency using Clean Water Act Section 104 grant funds under Assistance Agreement CD999776-01 to the California State Coastal Conservancy. The contents of this document do not necessarily reflect the views and policies of the U.S. EPA, the Coastal Conservancy, or of any other funding organization, nor does mention of tradenames or commercial products constitute endorsement or recommendations for use. This document should be cited as: David Magney Environmental Consulting. 2000. Calleguas Creek Watershed Wetland Restoration Plan. October 2000. (PN 97-0141.) Ojai, California, with Geo InSight International, Secor International Incorporated, and Wildlands, Inc. Prepared for California State Coastal Conservancy, Oakland, California and U.S. Environmental Protection Agency, San Francisco, California. This report is printed on recycled paper. Calleguas Creek Watershed Restoration and Preservation Plan Project No. 97-0141 - October 2000 Page i DMEC TABLE OF CONTENTS PAGE INTRODUCTION ................................................................................................... 1 BACKGROUND ............................................................................................................ 1 PROBLEM STATEMENT ............................................................................................. 2 Effects of Wetland Losses ................................................................................................... 2 OBJECTIVES ................................................................................................................. 3 WATERSHED CHARACTERIZATION ............................................................. 4 GENERAL WATERSHED DESCRIPTION ................................................................. 4 Physiography ....................................................................................................................... 4 Geology ................................................................................................................................ 4 Climate ................................................................................................................................. 7 Hydrology ............................................................................................................................ 9 Surface Water ................................................................................................................ 9 Groundwater .................................................................................................................. 14 Soils ..................................................................................................................................... 16 Plant and Wildlife Habitats .................................................................................................. 17 Grassland ....................................................................................................................... 17 Coastal Sage Scrub ........................................................................................................ 19 Chaparral ....................................................................................................................... 22 Rock Outcrop ................................................................................................................ 22 Woodland ...................................................................................................................... 23 Transitional .................................................................................................................... 24 Wetland ......................................................................................................................... 24 INVENTORY OF RIVERINE SYSTEMS .................................................................... 30 Inventory .............................................................................................................................. 30 General Stream Characteristics in the Calleguas Creek Watershed ..................................... 31 Streams in Rugged Topography .................................................................................... 31 Streams on Alluvial Fans .............................................................................................. 32 Streams on Alluvial Valleys .......................................................................................... 33 Streams on Delta Plains ................................................................................................. 33 DEVELOPMENT AND IMPACTS ............................................................................... 34 Historical Development in the Watershed ........................................................................... 34 Impacts to Streams as a Result of Development .................................................................. 36 Stream Discharge, Sediment Supply, and Channel Morphology .................................. 36 Water Quality ................................................................................................................ 39 Plant and Wildlife Habitat ............................................................................................. 40 APPROACH AND RATIONALE .......................................................................... 42 OVERALL OBJECTIVES ............................................................................................. 42 THE APPLICATION OF A TRUNCATED HGM APPROACH .................................. 43 Background........................................................................................................................... 43 C:\DMEC\Jobs\California\CoastalConservancy\Calleguas\Wetlands\Report\Calleguas Watershed Wetland Restoration Plan.doc Calleguas Creek Watershed Restoration and Preservation Plan Project No. 97-0141 - October 2000 Page ii DMEC PAGE The HGM Approach Explained............................................................................................ 43 The HGM Approach Used in this Document........................................................................ 44 Ecosystem Functions Defined............................................................................................... 45 SITE SELECTION CRITERIA....................................................................................... 46 A NOTE ON LIMITATIONS ......................................................................................... 49 RESTORATION AND PRESERVATION RECOMMENDATIONS................ 51 OVERVIEW .................................................................................................................... 51 EXAMPLE DESIGN RATIONALE ............................................................................... 51 GENERAL RECOMMENDATIONS ............................................................................. 54 Preserve Key Portions of the Watershed............................................................................... 54 Upland Portions of the Upper Watershed....................................................................... 54 Groundwater Recharge Zones ........................................................................................ 55 Large, Intact Channel-Floodplain Systems .................................................................... 56 Implement Storm Water Management Plans ........................................................................ 56 Manage Storm Water Facilities for Plant and Wildlife Habitat............................................ 57 Restore and Stabilize Stream Banks ..................................................................................... 58 Reduce Sediment Discharges from Orchards ....................................................................... 59 Redesign and Replace Undersized Culvert and Bridge Spans.............................................. 60 SPECIFIC RESTORATION SITE RECOMMENDATIONS......................................... 62 Overview............................................................................................................................... 62 Benefits ................................................................................................................................. 62 Conceptual Restoration Plans ............................................................................................... 64 Calleguas Creek/Revolon Slough Confluence (Sites 32/33).......................................... 65 Calleguas Creek at California State University, Channel Islands (Site 1) ..................... 71 Calleguas Creek at Camarillo