Fisher Slough Tidal Marsh Restoration Project Scaling Down the Restoration Planning & Analysis Framework to Evaluate Project Alternatives Project Sponsor/Partners The Nature Conservancy Dike District #3 Drainage District #17 Skagit County WWAA Local Landowners Tech. Adv. Committee WDFW SRSC USFWS NOAA NRCS SCD Consulting Team Tetra Tech Moffatt & Nichol URS Corp. Miller Consulting River Restoration Northwest Stream Restoration Design Symposium February 2009 Photo: Kirsten Morse
TODAY S PRESENTATION TOPICS Project Location, Scale, Hydrologic, Geomorphic & Habitat Context Restoration Objectives & Project Constraints Scaling the Restoration Planning Framework Downward Examples of Alternatives Analysis, Projected Outcomes & Plans Lessons Learned
PROJECT LOCATION, SCALE, GEOMORPHIC, HYDROLOGIC & HABITAT CONTEXT (A) Skagit River Runoff & High Flows Skagit River Floodplain Skagit Bay Tidal Cycling Tributary Watersheds
PROJECT LOCATION, SCALE, GEOMORPHIC, HYDROLOGIC & HABITAT CONTEXT (B) FLOODGATE BIG DITCH DRAINAGE CROSSING LEVEE SETBACK & TIDAL MARSH RESTORATION
PRIMARY RESTORATION OBJECTIVES Create Diverse Array of Native Vegetative Tidal Marsh Communities Restore Juvenile Chinook, Skagit Delta Rearing Areas Improve Fish Passage for Coho and Chum Spawning Access Improve Flood and Sediment Storage
SCALING DOWN THE RESTORATION PLANNING FRAMEWORK Skagit Chinook Recovery Plan Linkages Perform Detailed Baseline Assessments Evaluate Degradation, Changes & Effects Identify Project Constraints, Risks & Uncertainties Develop Design Criteria Evaluation of Concept Design Alternatives Selection & Implementation of the Plan
FINAL DESIGN ALTERNATIVES ANALYSIS Phase 1 Floodgate Retrofit w/ Self Regulating Structure Phase 2 Big Ditch Crossing Realignment Alignments Phase 3 Levee Setback & Tidal Marsh Restoration
Phase 1 Floodgate Retrofit w/ Regulating Closure Gates
Elevation (ft,navd88) FLOODGATE - OBSERVED FALL/WINTER HYDROLOGY Fisher Slough - Tidal & Flood Hydrology Fall & Winter Periods SKAGIT FISHER_US (EXIST) Fisher Flood Stage 20 15 EXISTING SUMMER OPS POST FLOOD GATES REOPEN GATES OPEN 10 5 FALL FLOOD OPS GATES CLOSED 0 10-Sep- 17-Sep- 24-Sep- 1-Oct- 8-Oct- 15-Oct- 22-Oct- 29-Oct- 5-Nov- 12-Nov- 19-Nov- 26-Nov- 3-Dec- Date (PST)
Elevation (ft,navd88) FLOODGATE - OBSERVED SPRING/SUMMER HYDROLOGY Fisher Slough - Tidal & Flood Hydrology Spring Runoff & Summer SKAGIT FISHER_US (EXIST) 14 12 JUVENILE CHINOOK MIGRATION PERIOD 10 8 6 4 2 GATES CLOSING MISS HIGH TIDES LACK OF MAINTENANCE TO LASH GATES OPEN IN 2008 SHOULD BE FULLY OPEN 0 17-Jun-08 18-Jun-08 19-Jun-08 20-Jun-08 21-Jun-08 22-Jun-08 23-Jun-08 24-Jun-08 Date (PST)
Existing Floodgate Degradation & Effects Floodgate Effects Gates closed 58% of time Operations & maintenance deficiencies Increases in water temperatures
Regulating Floodgate Retrofit Design Criteria Floodgate Design Criteria Expand/Change Gate Operations to Coincide w/ Juvenile Chinook Occupancy Increase % Time Gates Are Open Evaluate Juvenile Salmon Swim Criteria Maximize Tidal Prism Exchange & Marsh Inundation Areas Improve in Flood Storage Evaluate 1-Pair & 3-Pair Gates to Determine Functional & Cost Differences
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Peak Flows (cfs) 200,000 Regulating Floodgate Redefine Seasonal Operating Periods HIGH FLOOD RISK LESS RISK LOW RISK FALL/WINTER Skagit PERIOD River, Mt. SPRING Vernon Gage SUMMER Seasonality of Annual MIGRATION Peak Flows IRRIGATION & Juvenile Chinook Occupancy Periods for Fisher Slough PERIOD PERIOD Annual Peak Flow s Juvenile Chinook Estuarine Rearing Period 175,000 150,000 Juvenile Chinook Estuarine Rearing Period (High Occupancy) 125,000 100,000 Summer Irrigation Season - Gates Continually Open Operation 75,000 50,000 25,000 Future Juvenile Chinook Spring Migration Delayed Gate Operations (Open/Close ~10ft) 0 Months Winter Flood Standard Gate Operations (Open/Close ~7ft)
Water Surface Elevation (ft-navd88) Velocity (fps) 3 Regulating Floodgates Fish Passage Criteria REGULATING GATES ALLOW NEARLY FULL TIDAL INUNDATION 12 10 3 Regulating Floodgates - Spring/Summer Period w/ Levee Setback Velocity Skagit Elevation Slough Elevation 12 10 8 6 8 6 4 2 0-2 -4-6 4 2 0-2 -4-6 -8-10 EXCEEDANCE OF FISH 22-JunPASSAGE VEL. CRITERIA (MINIMAL) 24-Jun 26-Jun 28-Jun Date -8-10
Regulating Floodgate Design Alts. Summary Criteria Exist 1-Pair 3-Pair % Time Open (Total) 42% 80% 80% % Time Fish Passage (Velocity) N/A 95% >95% Tidal Inundation Area (acres) 10 39 49 Tidal Prism Volume (acre-ft) 20 56 134 Flood Storage @ Tidal Peak 2 14 12 Risks N/A Mixed Gates Flood Storage
Phase 2 Big Ditch Drainage Crossing Realignment
Phase 2 Big Ditch Drainage Crossing Realignment
Phase 3 Levee Setback, Tidal Marsh Restoration Evaluating 2 Distinct Alternatives Passive Marsh Restoration Active Marsh Restoration Hydraulic Modeling of Alternatives Simple Semi-quantitative Conceptual Models Vegetation Occurrence Erosion and Sedimentation Potential
Phase 3 Levee Setback, Tidal Marsh Restoration Passive Approach
Phase 3 Levee Setback, Tidal Marsh Restoration Passive Approach
Phase 3 Levee Setback, Tidal Marsh Restoration Active Approach
Phase 3 Levee Setback, Tidal Marsh Restoration Active Approach
Elevation (ft,navd88) Levee Setback & Tidal Marsh Restoration Flood Storage Improvements Fisher Slough - Tidal & Flood Hydrology Fall & Winter Periods SKAGIT FISHER_US (EXIST) Fisher Flood Stage FISHER_ACTIVE 20 15 3ft Reduction In Flood Stage 10 5 0 10-Sep- 17-Sep- 24-Sep- 1-Oct- 8-Oct- 15-Oct- 22-Oct- 29-Oct- 5-Nov- 12-Nov- 19-Nov- 26-Nov- 3-Dec- Date (PST)
Lessons Learned & Closing Complex Sites Need Detailed Site Assessments, Characterization & Data Collection Design Guidance for Tide/Floodgates Needed Vegetation & Inundation Data Collection & Modeling Collaborative Process is Successful Salmon Habitat Restoration and Floodplain Management Complimentary Benefits
Thank you.