Lamoille River Corridor Plan Johnson to Cambridge Lamoille County, Vermont February 22, 2017 Prepared by: Lamoille County Planning Commission P.O. Box 1637, 52 Portland Street Morrisville, VT 05661 With assistance from: Bear Creek Environmental, LLC 149 State St., Suite 3 Montpelier, Vermont 05602 Lamoille River Corridor Plan TABLE OF CONTENTS 1.0 INTRODUCTION ......................................................................................................................... 1 2.0 LOCAL PLANNING PROGRAM OVERVIEW .......................................................................... 2 2.1 RIVER CORRIDOR PLANNING TEAM .................................................................................. 2 2.2 GOALS AND OBJECTIVES OF THE PROJECT .................................................................... 2 2.2.1 State River Management Goals and Objectives ..................................................................... 2 2.2.2 Local Goals and Objectives ...................................................................................................... 3 3.0 BACKGROUND WATERSHED INFORMATION .................................................................... 3 3.1 GEOGRAPHIC SETTING ................................................................................................................ 3 3.1.1 Watershed Description.............................................................................................................. 3 3.1.2 Political Jurisdictions ................................................................................................................. 3 3.1.3 Land Use ..................................................................................................................................... 3 3.2 GEOLOGIC SETTING .................................................................................................................... 6 3.3 GEOMORPHIC SETTING ............................................................................................................... 7 3.3.1 Description and Mapped Location of the Assessed Reaches ................................................ 7 3.3.2 Longitudinal Profile, Alluvial Fans, and Natural Grade Controls .......................................... 9 3.3.3 Valley and Reference Stream Types ........................................................................................ 9 3.4 HYDROLOGY .............................................................................................................................. 10 3.4.1 USGS Gage and/or Stream Stats Information ...................................................................... 10 3.4.2 Flood History ............................................................................................................................ 10 3.5 ECOLOGICAL SETTING .............................................................................................................. 12 4.0 METHODS .................................................................................................................................... 14 4.1 FLUVIAL GEOMORPHIC AND HABITAT ASSESSMENT PROTOCOLS ........................................... 14 4.1.1 Phase 1 Methodology .............................................................................................................. 14 4.1.2 Phase 2 Methodology .............................................................................................................. 14 4.1.3 Bridge and Culvert ................................................................................................................... 14 4.2 QUALITY CONTROL/QUALITY ASSURANCE PROCEDURES ....................................................... 15 5.0 PHASE 1 AND PHASE 2 ASSESSMENT RESULTS ............................................................... 15 5.1 PHASE 1 RESULTS ...................................................................................................................... 15 5.1.1 SGAT ......................................................................................................................................... 15 5.1.2 SGAT, Remote Sensing, Local Knowledge, and Field Verification ....................................... 16 5.1.3 Lamoille River Report Impact Rating Methodology and Reach Results Summary ........... 16 5.1.4 Watershed Land Cover/Land Use- Step 4.1 .......................................................................... 16 5.1.5 Corridor Land Cover/Land Use- Step 4.2 .............................................................................. 17 5.1.6 Riparian Buffer Width- Step 4.3............................................................................................. 17 5.1.7 Channel Modifications- Step 5.4 ........................................................................................... 17 5.1.8 Dredging and Gravel Mining History- Step 5.5 ..................................................................... 18 5.1.9 Depositional Features- Step 6.3 ............................................................................................. 18 5.1.10 Meander Migration/ Channel Avulsions- Step 6.4 .............................................................. 18 5.1.11 Meander Width Ratio-Step 6.5 ............................................................................................ 18 5.2 PHASE 2 RESULTS ...................................................................................................................... 19 5.3 BRIDGE AND CULVERT ASSESSMENT ......................................................................................... 23 6.0 STRESSOR, DEPARTURE AND SENSITIVITY ANALYSIS .................................................. 25 6.1 DEPARTURE ANALYSIS AND STRESSOR IDENTIFICATION .......................................................... 25 6.1.1 Hydrologic Regime Stressors .................................................................................................. 25 6.1.2 Sediment Regime Stressors ..................................................................................................... 25 6.1.3 Reach Scale Sediment Regime Stressors ............................................................................... 26 6.1.4 Channel Slope Modifiers ......................................................................................................... 27 6.1.5 Boundary Conditions and Riparian Modifiers ...................................................................... 27 6.1.6 Constraints to Sediment Transport and Attenuation ........................................................... 28 6.2 SENSITIVITY ANALYSIS .............................................................................................................. 30 7.0 PRELIMINARY PROJECT IDENTIFICATION AND PRIORITIZATION ............................. 31 7.1WATERSHED-LEVEL OPPORTUNITIES ........................................................................................ 32 7.2 REACH-LEVEL OPPORTUNITIES ................................................................................................. 34 7.3 PREVIOUS SITE LEVEL RESTORATION EFFORTS ........................................................................ 46 7.4 PROPOSED SITE LEVEL RESTORATION OPPORTUNITIES ........................................................... 46 7.5 NEXT STEPS ............................................................................................................................... 56 8.0 GLOSSARY OF TERMS .............................................................................................................. 57 9.0 REFERENCES............................................................................................................................... 60 EXECUTIVE SUMMARY Lamoille River Corridor Plan Johnson to Cambridge, Vermont The Phase 2 stream geomorphic assessment study area focused on 6 stream reaches between the Railroad Street in Johnson and Pumpkin Harbor Rd in Cambridge Village. The Lamoille River HUC 1 has a watershed size of 182 square miles at the downstream end of the study area in Cambridge, Vermont. The combined length of the river reaches assessed is approximately 15 miles. The Lamoille River within the study area flows east to west through the Towns of Johnson and Cambridge. The Lamoille continues to flow westerly downstream of Cambridge and eventually joins Lake Champlain in Milton at an elevation of 95 feet above sea level. The Lamoille River reaches from Johnson to Hardwick were previously assessed and documented in a companion report (2010) entitled “Lamoille River Corridor Plan - Hardwick to Johnson, Vermont.” Four of six assessed reaches in the Lamoille HUC 1 study area (R08, R09, R11 and R13) were found to be in fair geomorphic condition. One reach, R12 was assessed as good geomorphic condition (based on administrative judgment) and one reach, R10 was assessed as poor condition. Geomorphic condition is determined based on the degree (if any) of channel degradation, aggradation, widening, and planform adjustment. Degradation is the term used to describe the process whereby the stream bed lowers in elevation through erosion or scour of bed material. Aggradation describes the raising of the bed elevation through an accumulation of sediment. The planform is the channel shape as seen from the air. Planform change can be the result of a straightened course imposed on the river through different channel management activities or a channel response to other adjustment processes such as aggradation and widening.