Lemon Creek Watershed Recovery and Management Plan July 2007 Lemon Creek Management and Recovery Plan July 2007 Statement of Purpose and Need As Juneau grows, the expansion of commercial and residential development requires careful planning and consideration to limit the impact of this growth on human and ecosystem health and safety. Current and proposed gravel extraction, construction of medium-density housing, and influx of commercial “box stores” in the Lemon Creek Valley create an urgent need to define an up-to-date management and recovery plan for Lemon Creek. The Lemon, Switzer, and Vanderbilt areas are a primary source of gravel in Juneau; as such, gravel extraction has driven the degradation of in-stream and riparian fish habitat in these areas over the last four decades. Rapid urban growth beginning in the early 1970’s resulted in a residential and commercial corridor along the lower reaches of Lemon Creek that constricts its naturally meandering flowpath. Extreme erosion upstream of the urban corridor has resulted in streambed aggradation and increased flood risk. Much of the Lemon Creek Watershed remains undeveloped; the creek and its watershed are appraised for recreational and educational public use and aquatic and terrestrial habitat. As Lemon and Ptarmigan Glaciers retreat, water quality impairment due to glacial activity is expected to improve significantly in the future. The challenge ahead is to minimize the impact of gravel extraction, necessary flood mitigation, and future development upon existing and potential uses dependent upon aquatic and riparian habitat. Lemon Creek is currently listed as impaired for sediment, turbidity, and habitat modification on the Alaska Clean Water Action (ACWA) 4b list. Water quality monitoring and biological studies designed to determine the extent of these impairments are largely lacking, and no baseline water quality or biologic data collected prior to gravel extraction are known to exist. The Alaska Department of Environmental Conservation developed a Total Maximum Daily Load (TMDL) report for Lemon Creek, published in 1995, based on limited data. The TMDL report identified several sources or potential sources of sediment and turbidity in the Lemon Creek watershed, outlined a monitoring strategy for collecting water quality data, listed several recovery actions, and defined sediment allocations for key land users in the area. The purpose of this report is to evaluate actions taken and information collected in the Lemon Creek area since the publication of the 1995 TMDL and apply this information to update the Lemon Creek recovery and management plan. An updated plan will assist local agencies, watershed groups, citizens, and land users to coordinate energy and resources as effectively as possible for the protection and improvement of water quality and fish habitat while providing relief from flood risk and supporting ongoing gravel extraction and development. The intended audience of this report includes citizens and agencies. -2- Lemon Creek Management and Recovery Plan July 2007 TABLE OF CONTENTS 1. INTRODUCTION ...................................................................................................................................................4 1.1 WATERSHED DESCRIPTION ................................................................................................................................4 1.2 GEOLOGY , FLORA AND FAUNA ........................................................................................................................10 1.3 HISTORY ...........................................................................................................................................................12 2. WATER QUALITY ..............................................................................................................................................14 2.1 WATER QUALITY REGULATIONS .....................................................................................................................14 2.2 LEMON CREEK WATER QUALITY ...................................................................................................................14 2.2.1 TMDL Loading Capacity Estimates ......................................................................................................15 2.2.2 Total Load Allocations ............................................................................................................................16 2.3 RELEVANT WATER QUALITY DATA ................................................................................................................19 Discharge and Solids Data ...............................................................................................................................19 Other Data ........................................................................................................................................................19 2.4 DESIGNATED USE IMPAIRMENTS .....................................................................................................................20 2.4.1 Sediment ...................................................................................................................................................20 2.4.2 Turbidity ..................................................................................................................................................21 2.4.3 Habitat Modification ...............................................................................................................................22 2.4.4 Other Pollutants of Concern ..................................................................................................................22 3. FISH AND FISH HABITAT.................................................................................................................................23 3.1 LEMON CREEK FISH SPECIES ..........................................................................................................................23 3.2 FISHERIES RESEARCH ......................................................................................................................................25 3.3 FISH HABITAT IMPACTS ...................................................................................................................................26 3.3.1 Erosion .....................................................................................................................................................27 3.3.2 Channel Alterations ................................................................................................................................27 3.3.3 Streambank and Riparian Disturbance ................................................................................................27 4. RECOVERY AND STEWARDSHIP ..................................................................................................................29 4.1 DISCUSSION ......................................................................................................................................................29 4.1.1 Urbanization and Land Use ...................................................................................................................30 4.1.2 Riparian Buffers ......................................................................................................................................36 4.1.3 Other Potential Pollutants ......................................................................................................................36 4.1.4 Fish Habitat .............................................................................................................................................37 4.1.5 Wetlands ..................................................................................................................................................38 4.2 GOALS AND ACTION ITEMS ..............................................................................................................................39 APPENDIX A: ACKNOWLEDGEMENTS............................................................................................................48 APPENDIX B: LEMON CREEK CHANNEL TYPES AND PROCESS GROUPS ...........................................48 APPENDIX C: LEMON CREEK AREA ZONING MAPS (CBJ, 2006)..............................................................52 APPENDIX D: 1995 LEMON CREEK IMPLEMENTATION PLAN.................................................................60 -3- Lemon Creek Management and Recovery Plan July 2007 1. INTRODUCTION 1.1 Watershed Description Lemon Creek is a medium-sized glacially-fed stream located in the Lemon Creek Valley, approximately five miles northwest of downtown Juneau, Alaska (Figure 1). Flowing east to west from the terminal lakes of the Thomas and Lemon Glaciers and emptying into Gastineau Channel, Lemon Creek courses through Tongass National Forest lands to a growing residential and industrial urban area. Elevations range from sea level to 5,600 feet (USGS); Lemon Creek is steeply bordered to the north by Heintzleman Ridge, to the south by Blackerby Ridge, and to the east by Lemon Creek Glacier and the Juneau Icefield. Thoma Alask s a ¹ Glacier Legend Lemon Creek Watershed Lemon Creek Trail Roads Lemon Creek Lemon Glacie r Canyo Ptarmigan No n Creek Glacier Sawmil Name Creek Mendenhall l Valley, Creek ~2 miles Lemo n Creek 00.5 1 2 3 4 Trail Kilometers Downtown Juneau, ~5 miles Figure 1: Lemon Creek Watershed, Juneau,