Michael Love P.E.h2odesigns.com/wp-content/uploads/2014/12/Salmon_C... · Microsoft PowerPoint -...

11/18/2014

Michael Love & Associates 1

Restoring Salmon Creeks Tidal Processes to Create a Diversity of Estuarine Habitats

Michael Love P.E.Michael Love & Associates, Inc.Eureka, CA

Trinity Associates

WallaceStructures

Nehalem Marine

Salmon Creek

SOUTH BAY

ENTRANCEBAY

11/18/2014


HooktonSlough

Salmon Creek 1870

Salmon CreekDrainage Area = 18 mi2

Ave. Rainfall: 40‐65 in/yr

Species: coho, chinook, steelhead, cuttroat trout

• Pre‐1850: Wiyot Tribe maintains seasonal fishing village at Salmon Creek Delta. (Pop. ~1,000)

• 1856: First timber mill and harvest in Salmon Creek watershed, by 1900 much of the basin was logged

• 1883: Hookton channel first dredged for barging timber

• 1900: Conversion of saltmarsh to agricultural lands by Z. Russ and Sons Company; Salmon creek channelized, tidegates and diversion structures constructed

• 1989: Refuge purchased from McBride Family. Enhancement projects include; freshwater ponds, 2,500 ft of meandering stream, tree planting, installation of “fish door” in tide gate

Timeline of Salmon Creek

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Visitor Center

College of the Redwoods

Tidegates

Vance Parcel(privately owned)

PrivateParcel

Property Boundaries within Salmon Creek Delta

HBNWR

Visitor Center

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Focus Area for Salmon Creek Estuary Enhancement

Visitor Center

Ground Elevations

7’6’

5’

<4’

South Bay

Salmon Creek – Humboldt Bay

Mean Higher High Water (NAVD 88): Hookton Slough = 6.2 ftHookton Slough Spring Tides > 8 ft

Tidegate

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Pre-Project Hydrologic Conditions

Visitor Center

Salmon Creek TidegatePartial Barrier to Spawining Salmonids

3-GatesDownstream Side

Hookton Slough at Mid-Tide

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Project Goals and Objectives

1. Improve fish passage into Salmon Creek

2. Create estuarine diversity (an ecotone) extending into the Upper Refuge

3. Create stable channel size for increased tidal prism

4. Improve floodplain connectivity & drainage

5. Reduce fish stranding

Enhance the diversity of the Salmon Creek Estuary while working within the physical constraints and multi‐species management objectives of the Refuge

6. Create off‐channel ponds and marshes suitable for salmonids and other estuarine fish

7. Raise subsided land to reestablish native saltmarsh

Expanding the Freshwater‐Saltwater Ecotone

Ecotone – Zone of gradual transition between two distinct ecological communities

Lower ecotone consists of multiple channels

- Fresh‐saltwater interface at high flows

- Continuous tidal influence (below MLLW)

Upper ecotone consists of single channel with off‐channel wetlands

- Brackish at low flows

- Influenced during higher tides and higher flows.

Bay (saltwater)

Lower Ecotone

Upper Ecotone

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Phase 1: Salmon Creek Tide GateDesign Objectives

1. Minimum 30‐year design life

2. Provides uninterrupted passage in/out of Salmon Creek for Adult Salmon/Steelhead

3. Gates sized to drain floodwaters similar to ungated system at 2‐year flood

4. Allows for a muted tide that can:

• Support a complex estuarine ecotone on the Refuge (marine to freshwater)

• Protects Northern Refuge and off‐Refuge infrastructure from tidal flooding

• Adaptable to sea‐level rise over design life

Target: Highest Tide = 5.5 feet

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Inundation at Varying Tidal Elevations

7’6’

5’

<4’

South Bay

Salmon Creek – Humboldt Bay

Mean Higher High Water (NAVD 88): Hookton Slough = 6.24 ftSalmon Creek (Existing) = 3.5 ftSalmon Creek (Proposed) = 4.8 ft

Tidegate

Tide GateDesign

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Predicted Water Surface Elevations at Tidegatesduring 2-yr 24-hr storm event

Day 1 Day 2 Day 3

Hookton SloughMHHW

MLHW

MHLW

MLLWAll velocities through new gates < 6 ft/s

Hookton SloughMHHW

MLHW

MHLW

MLLW

Day 1 Day 2 Day 3

Velocity > 6 ft/s

Day 1 Day 2 Day 3

Salmon Creek Muted Tide Gates (constructed 2008)

New Gates enlarge muted tidal prism (MLLW to MHHW) from 35 AF to 130 AF

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1. Construct geomorphically stable features for the muted tide condition

2. Use excavated spoils to raise subsided lands, recreate native salt marsh and maintain tidal prism

3. Construct side‐channel and off‐channel ponds suitable for overwintering salmonids (approximately 3 acres)

4. Maintain fresh/low saline waters in upper ecotone (near Refuge boundary) at winter baseflow

Phase 2: Salmon Creek Channel, Pond, Marsh HabitatDesign Objectives

Spoils from channel excavation used to raise subsided land and restore salt marsh.

30,500 cy

Salmon Creek Overflow

New TidegateNew Tidegate

4,600 cy

7,500 cy

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fdSalmon Creek – Humboldt Bay

Based on Vegetation-Elevation Data from Eicher (1987) and NOAA Tide Records from North Spit (1993-2010). Adapted from Conor Shea, USFWS.

0%

5%

10%

15%

20%

25%

Ave

. H

ou

rs I

nn

un

dat

edp

er D

ay

SpartinaDominated

MixedMarsh

SarcocorniaDominated

Marsh

Mudflat/ Open

Channel

MHHW (North Spit)

0.0

1.2

2.4

3.6

4.8

6.0

Duration of Saltmarsh-Mud Flat Inundation in Hookton SloughUpstream and Downstream of Salmon Creek Tidegate

7.91 ft

3.86 ft

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0 2 4 6 8 10 12 14 16 18 20 22 24

Average daily duration of tidal inundation (hours)

Ele

vatio

n -

NA

VD

88 D

atum

(ft)

Hookton Slough (Downstream of tidegate)

Salmon Creek (Upstream of tidegate)

Inundation - Duration curves were constructed using water level data collected between 6/5/02 and 9/9/02.

Saltmarsh Mud Flat

3.3 ft

3.9 ft

5.4 ft

4.2 ft

7.9 ft

, Existing

Salmon Creek with New Muted Tide Gates

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Salt Marsh Vegetation Recruitment ‐Salmon Creek Overflow

Placed Fill (2010)

SarcocorniaMarsh (2012)

Salmon Creek Tidal Channel Design

Reach 3

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ReachReach Length

Channel Type

Top Width at MHHW

Channel Depth

Contributing Tidal Prism

(MHHW‐MLLW)

1 805 ftTemporary

Grade Control18 ft 8.2 ft 1.2 AF

2950 ft

Construct Slough

25 ft 8.3 ft 6.9 AF

3925 ft

Construct Slough

31 ft 8.8 ft 9.6 AF

4 2,100 ftSelf‐AdjustSlough

22 ft(15 ft)*

7.4 ft(7.3 ft)*

3.3 AF

5 1,525 ftConstruct Slough

36 ft 8.2 ft 14.1 AF

6 700 ftSelf‐AdjustSlough

52 ft(32 ft)*

8.1 ft(7.9 ft)*

21.1 AF

Overflow AreaMarsh/Mud‐flats/Sloughs

‐ ‐80 AF

(105 AF)** Existing conditions in parenthesis


-6

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

7

8

9

10

11

12

0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000

Distance from Salmon Creek Tide Gate (feet)

Ele

vati

on

(N

AV

D88

fee

t)

Refu

ge

Bo

un

dary

Humboldt Bay National Wildlife Refuge

Sal

mo

n C

reek

Tid

eg

ate

Ho

okto

nR

oad

Bri

dg

e

Design MHHW

Reach 2 (Constructed)

Existing Channel Invert


Reach 6 (to Self Adjust)



Reach 4(to Self Adjust)

Private Property

Bridge Footing(Approx.)

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Pond 3

Pond 4

Pond 2

Pond 1

Old Channel

Off‐Channel & Side‐Channel Ponds (Constructed 2011)

Pond 0

Salmon Creek

Salmon Creek Pond 3 Design

MHHW

MLLWResidual Pool

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Off‐Channel & Side‐Channel Pond Dimensions

Pond Number

Pond Outfall Station

Outfall Weir Elevation (NAVD 88)

Tidal Prism from Pond

Residual Pool Depth

1 40+30 2.5 feet 1.4 AF 3.5 feet

2 38+25 3.0 feet 0.6 AF 3.0 feet

3

35+75 Upstream

3.5 feet1.5 AF 3.8 feet

33+00 Downstream

2.8 feet

4

29+75 Upstream

3.0 feet

0.35 AF 5.0 feet27+50

Downstream3.5 feet

Side Channel (Pond 4) Confluence with Salmon Creek

Downstream Pond Sill Elev. 3.5 ft (NAVD88)

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Unsteady HEC‐RAS Model of Proposed Project

Model Predicted Channel Conditions near Pond 3

2400 1200 2400 1200 2400 1200 2400 1200 2400 120001Jan2005 02Jan2005 03Jan2005 04Jan2005 05Jan2005

-2

0

2

4

6

8

-200

0

200

400

600

800

1000

Riv er: Salmon Reach: Realigned RS: 3280

Time

Sta

ge

(ft)

Flo

w (

cfs)

2-year Flood Event Water Level and Flow

Winter Base FlowWater Level and Flow

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Salinity Mass Balance Analysis between MLLW‐MHHWat Winter Baseflow (15 cfs)

Freshwater in Estuary

Conclusion: Freshwater dominated to Pond 3 During Moderate Winter Baseflow Conditions

20 In‐Channel Large Wood Structures


Total of 110+ Logs Placed in Estuary

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Deflector Logs to force local scour around Pond Mouths


Logs Anchored together and cabled to 2‐Ton Rocks. Each log required one 2‐Ton Rock to counter buoyancy

12 Complex Wood Cover Structures in the 4 Ponds

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Project

Effectiveness Monitoring

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Sedimentation in Ponds

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

Pond 1 Pond 2 Pond 3 Pond 4

Volume (CY)

Salmon Creek at HBNWRComparison of Design Surface (2010) and Monitoring (2013) Surveys

Excavation

Depostion

7,936 CY

647 CY 486 CY 2,416 CY 779 CY

4,394 CY

5,533 CY

1,937 CY

Salmon Creek Pond 3 SedimentPatterns

MHHW

Residual PoolSedimentation

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Sedimentation in PondsSalmon Creek Pond 2 SedimentPatterns

MHHW

Residual Pool

Self‐Maintaining Channel at Mouth of Pond 2

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Changes in Tidal Prism

2011 to 2013

Tidal Storage Range

(Elevation, ft)

Design Tidal Volume, 2011

(ac-ft)

Current Tidal Volume, 2013

(ac-ft)

% Change

Channel -0.7 to 4.7 4.15 4.04 -3%

Pond 0 3.7 to 4.7 0.3 N/A N/A

Pond 1 2.5 to 4.7 1.45 1.48 +2%

Pond 2 3.0 to 4.7 0.63 0.59 -6%

Pond 3 2.8 to 4.7 1.12 0.68 -39%

Pond 43.0 to 4.7 0.34 0.22 -34%

Salinity & Fish Monitoring (from Mike Wallace, CDFG)

11/18/2014


Salinity & Fish Monitoring (from Mike Wallace, CDFG)

Questions?

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