APRIL 2015 Biological Mitigation and Monitoring Plan for the Humboldt Bay Power Plant Final Site Restoration Project PREPARED FOR PREPARED BY Pacific Gas & Electric Company Stillwater Sciences Environmental Services Department 850 G Street, Suite K Arcata, CA 95521 3401 Crow Canyon Road San Ramon, CA 94583 Stillwater Sciences Mitigation and Monitoring Plan for the HBPP Final Site Restoration Project Suggested citation: Stillwater Sciences. 2015. Biological Mitigation and Monitoring Plan for the Humboldt Bay Power Plant Final Site Restoration Project, Humboldt County, California. Prepared by Stillwater Sciences, Arcata, California for Pacific Gas and Electric Company, San Ramon, California. Cover photos: Photos taken by Stillwater Sciences 2013-2015. Mit-B pond (top left), ruby- crowned kinglet in Rest-1 (top right), Duck Pond (bottom right), and Rest-1 (bottom left). April 2015 Stillwater Sciences i Mitigation and Monitoring Plan for the HBPP Final Site Restoration Project Table of Contents 1 INTRODUCTION AND BACKGROUND ........................................................................... 1 1.1 Project Description and Proponent .............................................................................. 1 1.2 Project Location ........................................................................................................... 1 1.3 Purpose of this Plan ..................................................................................................... 3 2 IMPACTS ON SPECIAL-STATUS HABITATS AND SPECIES ..................................... 3 2.1 Wetlands ...................................................................................................................... 3 2.2 Plants ............................................................................................................................ 6 2.3 Fish and Wildlife ......................................................................................................... 6 2.4 Sea Level Rise ............................................................................................................. 7 3 PERMITTING AND MITIGATION NEEDS ...................................................................... 8 3.1 Restoration Requirements from Previous Permits ....................................................... 8 3.1.1 Charlie Road .......................................................................................................... 9 3.1.2 ISFSI Support Office Parking Lot (Contractor Parking Lot #2) ........................... 9 3.1.3 Bayview Heights ................................................................................................. 10 3.1.4 Trailer City .......................................................................................................... 10 3.1.5 Alpha Road .......................................................................................................... 11 3.1.6 Rest-1 .................................................................................................................. 11 3.1.7 Contractor Pedestrian Trail ................................................................................. 11 3.2 Low-Impact Design and Stormwater Management ................................................... 12 3.3 New Impacts on Existing Wetlands ........................................................................... 12 3.3.1 Alpha Road .......................................................................................................... 12 3.3.2 Intake Canal and Buhne Point Wetland Preserve ................................................ 13 3.3.3 Bayview Heights ................................................................................................. 13 3.3.4 Duck Pond ........................................................................................................... 14 3.3.5 Frog Pond stormwater detention basin ................................................................ 14 3.3.6 King Salmon Avenue wetlands ........................................................................... 15 3.4 Proposed Restoration and Mitigation Ratios and Schedule ....................................... 15 4 PROPOSED RESTORATION AND MITIGATION ........................................................ 21 4.1 MIT-7 ......................................................................................................................... 24 4.1.1 Existing ecological conditions ............................................................................. 24 4.1.2 Mitigation goals, objectives, and success criteria ............................................... 24 4.1.3 Mitigation implementation .................................................................................. 25 4.1.4 Sea-level rise ....................................................................................................... 28 4.2 ISFSI Stormwater Detention Basin ............................................................................ 28 4.2.1 Existing ecological conditions ............................................................................. 28 4.2.2 Mitigation goals, objectives, and success criteria ............................................... 28 4.2.3 Mitigation implementation .................................................................................. 29 4.3 Bayview Heights ........................................................................................................ 31 4.3.1 Existing ecological conditions ............................................................................. 32 4.3.2 Mitigation goals, objectives, and success criteria ............................................... 32 4.3.3 Mitigation implementation .................................................................................. 32 4.3.4 Sea-level rise ....................................................................................................... 35 4.4 Trailer City Stormwater Detention Basin .................................................................. 35 4.4.1 Existing ecological conditions ............................................................................. 36 4.4.2 Mitigation goals, objectives, and success criteria ............................................... 36 4.4.3 Mitigation implementation .................................................................................. 36 April 2015 Stillwater Sciences ii Mitigation and Monitoring Plan for the HBPP Final Site Restoration Project 4.5 Shoreline Wetland Mitigation Area ........................................................................... 38 4.5.1 Existing ecological conditions ............................................................................. 38 4.5.2 Mitigation goals, objectives, and success criteria ............................................... 38 4.5.3 Mitigation implementation .................................................................................. 39 4.5.4 Sea-level rise ....................................................................................................... 41 4.6 Contractor Pedestrian Trail ........................................................................................ 41 4.6.1 Existing ecological conditions ............................................................................. 41 4.6.2 Mitigation goals, objectives, and success criteria ............................................... 41 4.6.3 Mitigation implementation .................................................................................. 42 4.6.4 Sea-level rise ....................................................................................................... 45 4.7 Buhne Point Wetland Preserve Fringe Area .............................................................. 45 4.7.1 Existing ecological conditions ............................................................................. 45 4.7.2 Mitigation goals, objectives, and success criteria ............................................... 45 4.7.3 Mitigation implementation .................................................................................. 46 4.7.4 Sea-level rise ....................................................................................................... 46 4.8 Frog Pond stormwater basin ...................................................................................... 46 4.8.1 Existing ecological conditions ............................................................................. 47 4.8.2 Mitigation goals, objectives, and success criteria ............................................... 47 4.8.3 Mitigation implementation .................................................................................. 47 4.9 Charlie Road .............................................................................................................. 48 4.9.1 Existing ecological conditions ............................................................................. 48 4.9.2 Mitigation goals, objectives, and success criteria ............................................... 48 4.9.3 Mitigation implementation .................................................................................. 48 4.9.4 Sea-level rise ....................................................................................................... 48 4.10 Alpha Road Overflow Parking Areas ........................................................................ 49 4.10.1 Existing ecological conditions ............................................................................