Middle and Lower Molalla River Restoration Action Plan 2011
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Middle and Lower Molalla River Restoration Action Plan Prepared for Molalla River Watch / Molalla River Watershed Council and Molalla River Improvement District Prepared by Cascade Environmental Group, LLC 222 NW Davis Street, Suite 317 Portland, Oregon 97209 (503) 894‐8585 Contact: John Runyon November 2011 Middle and Lower Molalla River Restoration Action Plan — November 2011 Contents Section Page Introduction ............................................................................................................................. 1 Watershed Setting ................................................................................................................... 5 Issues and Restoration Approaches ....................................................................................... 8 Flooding ....................................................................................................................... 9 Low Flows and High Water Temperatures ................................................................ 10 Habitat Modifications ................................................................................................. 10 Fragmentation of Wildlife Habitat .............................................................................. 11 ESA-Listed Fish ......................................................................................................... 11 General River and Floodplain Characteristics ....................................................................... 13 Coordinate Systems Used ......................................................................................... 13 Molalla River Floodplain Characteristics ................................................................... 14 Lack of Secondary Channels and Off-Channel Habitat .................................... 14 Active Channel Migration .................................................................................. 15 Water Quality: High Water Temperatures and Some Nutrients ................................. 15 Reach Descriptions ............................................................................................................... 34 Reach 6 (Rkm 44 to Rkm 41) .................................................................................... 34 Reach 5 (Rkm 41 to Rkm 33) .................................................................................... 35 Reach 4 (Rkm 33 to Rkm 18) .................................................................................... 36 Reach 3 (Rkm 18 to Rkm 10) .................................................................................... 39 Reach 2 (Rkm 10 to Rkm 3) ...................................................................................... 40 Reach 1 (Rkm 3 to Rkm 0.00) ................................................................................... 43 Priorities for Action ................................................................................................................ 44 Restoration Goals ...................................................................................................... 44 Recommended Restoration Actions .......................................................................... 45 Restoration Activities for the Entire Middle and Lower Molalla River ........................ 45 Landowner Outreach and Education ................................................................ 46 Invasive Plant Species Control ......................................................................... 46 Fish Population and Passage Barrier Assessment .......................................... 47 Evaluation of Areas at High Risk of Flooding ................................................... 48 Restoration Priority of Individual Reaches ................................................................. 48 Project Opportunities ............................................................................................................. 51 Glossary ................................................................................................................................... i Appendix A: U.S. Geological Survey Report: Geomorphic Setting, Aquatic Habitat, and Water-Quality Conditions of the Molalla River, Oregon i Middle and Lower Molalla River Restoration Action Plan — November 2011 Figures Figure Page Figure 1. Floating the lower Molalla River (Reach 4) with Bill Taylor and Kathryn Duthie, board members of Molalla River Watch and Molalla River Improvement District, respectively, July 2011. .......................................................................................... 4 Figure 2. Overview of the Molalla River watershed and the middle and lower river channel and floodplain (divided into reaches, see text below) that is the focus of this action plan…….. ................................................................................................................ 6 Figure 3. An example of how large portions of the City of Canby are perched above the Molalla River on bluffs composed of Missoula Flood deposits. .............................. 7 Figure 4. The maps here and on following pages show the six reaches delineated by the USGS study, depicting the channel location, extent of the historical floodplain, and features that constrain active channel movement (bedrock and revetments) ....... 16 Figure 5. The HAWS maps here and on the following pages show the historical floodplain of the Molalla River and delineate side channels and other secondary channel features that are important for both fish and wildlife habitat and absorbing floodwaters. .......................................................................................................... 25 Figure 6. Aerial photos showing shifts in wetted channel location in Reach 3 in 1994, 2000, 2006, and 2010 ..................................................................................................... 33 Figure 7. The Molalla River within Reach 6, illustrating how bedrock shapes the river’s habitat and restricts channel movement ............................................................... 35 Figure 8. An example of an engineered revetment along Reach 5 that protects South Molalla Forest Road from erosion by the river. ..................................................... 36 Figure 9. An example of an eroding bank in Reach 4. ........................................................ 37 Figure 10. Aerial photos showing the extent of bank erosion from lateral migration of the river channel along a section of Reach 4 in 1994, 2000, 2006, and 2010 ........... 37 Figure 11. An example of a large wood jam in Reach 4. ....................................................... 39 Figure 12. An example of the wide active channel area, large wood, and extensive floodplain forests within Reach 3. ......................................................................................... 41 Figure 13. Aerial photos (2010 top;1994 bottom) illustrating the wide and active floodplain within Reach 3 ...................................................................................................... 42 Figure 14. An aerial photo of Reach 1, which extends from the confluence of the Pudding River to the Willamette River ................................................................................ 43 Figure 15. An example of a Japanese knotweed infestation along Reach 4 of the Molalla River. .................................................................................................................... 47 Figure 16. Restoration project site locations ......................................................................... 55 ii Middle and Lower Molalla River Restoration Action Plan — November 2011 Tables Table Page Table 1. Major Floods on the Molalla River since 1964 ......................................................... 9 Table 2. Restoration Priority of Each Reach. …………………………………………….…… 48 Table 3. Restoration Project Sites, Habitat Issues, and Restoration Opportunities ............ 50 Table 4. Criteria for Ranking Restoration Projects .............................................................. 53 Table 5. Restoration Project Priority Ratings for Each Criterion .......................................... 55 iii Middle and Lower Molalla River Restoration Action Plan — November 2011 Acknowledgments Funding for this project was provided by the Oregon Watershed Enhancement Board (OWEB grant # 210-3007) and the Oregon Governor's Fund for the Environment (administered by the National Fish and Wildlife Foundation). The Middle and Lower Molalla River Restoration Action Plan is dedicated to the memory of Bob Reynolds. His leadership of the Molalla River Improvement District made this project possible. The following organizations and individuals contributed to this plan: U.S. Geological Survey: Kurt Carpenter, Chris Magirl, Christiana Czuba, Mathieu Marineau, Steve Sobieszczyk, Jonathan Czuba, and Mackenzie Keith Oregon Department of Fish and Wildlife: Todd Alsbury Clackamas County Soil and Water Conservation District: Jeremy Baker and Jenne Reische Molalla River Improvement District: Kathryn Duthie and Alan Gallagher Molalla River Watch, Inc.: Bill Taylor and Kay Patteson Isaac Sanders (previously with the Oregon Department of Fish and Wildlife) and Cindy Kolomechuk (previously with Clackamas County Soil and Water Conservation District) assisted with the early phase of this project. We also want to thank all the Molalla River landowners who volunteered to participate in restoration projects.