-- Lessons from a successful salmon stream and estuary relocation on Gravina Island

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Stephen Briggs
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1 Re-inventing Government Creek -- Lessons from a successful salmon stream and estuary relocation on Gravina Island Jon Houghton, Ph.D. and Derek Ormerod, M.S., P.E. - Pentec Environmental/Hart Crowser, Inc. D. Shane Cherry, M.S. - Cherry Creek Environmental Lance Mearig, P.E. - USKH Corporation February 2, 2010 contact: jon@pentecenv.com

2 Project Background FAA: Need to expand RSA by 1000 ft on either end Tongass Narrows Government Cr. Airport Cr. Boulder Cr. Alternative: long culvert

3 Adaptive Management by IDT - Interdisciplinary Team (IDT=ADOT&PF, ADF&G, NMFS, FWS, USACOE and consultant team) - Reviewed and Approved: > Approach > Design > Monitoring Plan - Review Monitoring Reports - Review and approve AM actions

4 Decision: Re-route Government Cr. into Boulder Cr. channel near mouth; and create new estuary (alternative option: very long culvert)

5 Project Elements Mainstem; 3 Side Channels; Expanded Estuary; North Tributary

Statistics: Constructed 2006 2007 Stripped and saved portion of overburden soil/vegetation Blasted, ripped, and moved 380,000

6 Statistics: Constructed Stripped and saved portion of overburden soil/vegetation Blasted, ripped, and moved 380,000 cy of rock and till Maximum depth of cut approximately 80 feet Excavated to flat flood plain, in dry, w/o technical oversight

7 Typical cross section 30 to 80-foot cut to flood plain (~150 foot wide) Then

8 With Bio-/Geomorpho-logist oversight (!): Excavated main channel and 3 side channels Built ~2,050 lineal feet of new channel, plus ~800 feet of side channels Installed habitat features (in dry) - Stream bed gravel - Approx. 100 boulders 2 12 ft in diam. - Approx. 50 trees w. roots/limbs Flow initiated August 2007

9 Monitoring Plan Schedule Pre- and Years 0, 1, 3, 5 In Stream - Channel topography Standard habitat measures (retention of LWD) Bed grain size (pebble counts) Riparian vegetation Salmon spawning Fry rearing (coho) In Estuary Saltmarsh area Eelgrass Fry rearing (coho) contact: jon@pentecenv.com

10 Stream Evolution

from eroding floodplain and glacial till Have far exceeded

11 Spawning Gravel Original bed material did not meet spec Too much sand and not enough gravel washed away Good gravel recruitment from eroding floodplain and glacial till Have far exceeded performance goal (1,200 sf) each year, and continues to stabilize and expand

12 Abundant Salmon Use Pinks spawned within 2 wks of flow initiation 2009 return of that cohort Pink salmon observed in the constructed reaches! Also, abundant juv coho, some DV, trout fry, likely chum spawning, and one lonely female Chinook!

during typical flows With AMT/IDT ok, created

13 Upper Cascade Fix Potential cascade fish barrier observed adult fish struggling to get upstream even during typical flows With AMT/IDT ok, created pools/steps in bedrock and added boulders to break up flow

14 Estuary Design Original tree/hwl New estuary created by excavating and re-grading upland forest to encourage tidal inundation Bed rock encountered in excavation Salt-marsh vegetation salvaged during construction

15 Salt-marsh vegetation Sod transplants doing well and spreading Year 2: first observed seedlings Distinct lack of saline inundation on upper portions of beach tracking by line of alder dominance

16 Estuary Erosion Significant intertidal erosion due to increased stream power Delta growth and braided channel Pilings not observed during construction!

17 Estuary Evolution Areas of Change: Low-tide channel erosion Delta formation Eelgrass loss in delta Clam resources affected Salt-marsh vegetation mixed with riparian vegetation

18 Estuary Step Work During Before Part of Adaptive Management Work Potential bedrock ledge fish barrier Created pools/steps in bedrock ledge After

Floodplain Erosion Routine overbank flow

19 Floodplain Erosion Routine overbank flow causes regular inundation and scouring of floodplain Recruits spawning gravel to channel Has created additional side channels and pools that isolate fish as water recedes Inhibits establishment of floodplain vegetation

of veg Vegetation Islands of armored sod from nearby

20 Vegetation Establishment Overbank flow scouring floodplain has allowed minimal natural recruitment of veg Vegetation Islands of armored sod from nearby forested uplands created as part of 2008 Adaptive Management

deposition clogging lower side channel Varying levels of

21 Side Channels Created to provide juvenile coho rearing habitat Have had concerns with in-flow rates and sediment deposition clogging lower side channel Varying levels of effectiveness based on amount of flow Do support juvenile coho

22 Created to provide juvenile coho rearing habitat Varying levels of habitat quality based on amount of flow Very dense pink spawning in 2009 North Tributary

23 Success Criteria Stream Channel No barriers to upstream passage of juv at normal flows (tough!) Pink and chum shall spawn Instream structures shall remain (60% thru Year 5) Coho shall rear Native trees (2 spp.) by Year 3 No excessive erosion on cut side slopes Side channel water quality ok for fry Estuary Saltmarsh area (Year 3 and 5) No excessive channel or beach erosion Coho shall rear

all fish-related criteria Vegetation of flood plain uncertain

24 Conclusions Rate of change, high in Year 1, has slowed in Year 2 Successful salmon spawning and rearing habitat Appear to be meeting all fish-related criteria Vegetation of flood plain uncertain Estuary erosion still a concern, but stabilizing Adaptive management can work!

25 Questions? (Upstream reference reach) contact:

Fish Passage at Road Crossings

Fish Passage at Road Crossings 1 Crossing Design Workshop Outline 1:00 to 2:00 Intro, Design Overview, Channel Width 2:00 to 2:15 Break 2:15 to 3:15 No-Slope, Stream Simulation Design 3:15 to 3:30 Break