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1

Where the Land Meets the

Water

KCD SHORELINE LANDOWNERS

WORKSHOP

Vashon Island

July 13, 2019

Geologic History Of

Puget Sound Shorelines

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The Maximum Extent

of the last glaciation,

approximately

15,000 years BCE.

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Puget

Lobe, (Ice)

OutwashProglacial Lake

Lake Sediments

Pre-glacial Sediments

Glacial Till

Mastodon

North

(Bellingham)

South

(Olympia)

Direction of Glacial Advance

Glacial Till

Typical Puget Sound Bluff Stratigraphy

Advance

Outwash

Lake

Sediments

Pre-glacial

Sediments

Recessional Outwash

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Photo by Shari Maria Silverman

Pre-Glacial

Sediments

Lake

Sediments

Outwash Glacial Till

Unmodified

Glacial Upland

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Troughs Scoured

by Subglacial

Meltwater Flow

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Glaciated Upland

Puget Sound

Earth

Post-Glacial Ground Surface

Wave-cut Bench

Current Bluff

Upland

Bluff

Wave-cut Bench

Deep Water

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MacLennan et al., (2018) Long-Term Bluff Recession Rates

in Puget Sound: Implications for the Prioritization and

Design of Restoration Projects. Prepared for Wash. St.

Dept. of Fish and Wildlife by Coastal Geologic Services

185 sites

Average Rate = 0.29 ft/yr

COASTAL BLUFF PROCESSES

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Glaciated Upland

Puget Sound

Earth

Post-Glacial Ground Surface

Wave-cut Bench

Current Bluff

Bluff Retreat by Single-Grain Erosion

Bluffs south of Kayak Point in Snohomish County, Photo by Hugh Shipman

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Failing culvert

Erosion by Flowing Water

Shallow Landslides

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Surface Water Draining

Over Bluff Face

2020

Burlington

Northern-Santa

Fe Freight

Train, Everett to

Seattle,

December 2018

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Deep-Seated Landslides

Figure Curtesy Don Tubbs

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23

Deep-Seated Landslides

Ground Water

Emerging as Seepage

from the Bluff Face

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Perkins Ln, Seattle, 1996.

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Carlyon Beach\Hunter Point Landslide, 1999

Photo by Hugh Shipman

Beach Formation and

Longshore Drift

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Glaciated Upland

Puget Sound

Earth

Post-Glacial Ground Surface

Wave-cut Bench

Current Bluff

Beaches

MLLW

MHHW

Low tide terrace

(Fine sand and silt)

Beach face

(Sand and gravel)

Backshore

Dune and Strand

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CGS field photo, 2004

Marine View Park,

City of Normandy Park

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Naset Beach, Cape Cod MA

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Marrowstone Island, WA

. Photo: Kris Symer

Beach Sediment Composed of Lag from Bluff

Erosion

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Sea Level Rise is already occurring

39

0

1

2

3

4

5

6

7

8

9

2010 2020 2030 2040 2050 2060 2070 2080 2090 2100 2110

Feet

Rel

ativ

e to

19

91

-20

09

ave

rage

99 90 83 50 17 10 1 0.1

0.1%

1%

10%

90%

99%

50%

17%

83%

Projected Sea Level Rise (Seattle)

Pro

ba

bili

ty o

f E

xce

ed

an

ce

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Glaciers/land ice melting

= 35%

Thermal Expansion

= 40-50%

A 1 foot rise in sea level =

100-year flood event occuring every 2 years

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Bluff erosion rates are predicted to

double by 2100

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Questions?

Nearshore

Ecology

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Nearshore Ecosystem

Riparian

Forest

Bluffs

Eelgrass

Estuary

Beach Kelp

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Salish Sea

Semi-Enclosed Coastal Sea

• Steep coastline with narrow

nearshore zone

• Mixed sand/gravel beaches

• Strong regional gradients

• Tides-Twice a day

• Ecology strongly linked to

geology and physical

processes

• Rich biological resources

Puget Sound Nearshore Ecosystem

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Chesapeake BayPuget Sound

Puget Sound Supports

Over 200 spp. of fishes

100’s of spp. of aquatic

invertebrates

10+ spp. of marine

mammals

100’s of spp. of wildlife

Photo: Jen Vanderhoof

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Ratfish

Photo: Jen Vanderhoof

Photo: Jen Vanderhoof

Photo: Jen Vanderhoof

Grunt SculpinSpeckled

Sanddab

Gunnels

Photo: Jen Vanderhoof

Spiny Lumpsucker

Photo: Robyn Ricks

Photo: Robyn RicksPhoto: Kim Stark

Photo: Jen Vanderhoof

Wildlife

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From Pew Charitable Trust

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What size gravel do they spawn in?

Adapted from Phil Dionne

Surf Smelt

Sand Lance

30 to 40% of beaches in King County are

known spawning beaches

Spawning surf smelt

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Eelgrass

Kelp/Algae

Mego Huang / UW

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Photo by Hans Berge

Pink Coho

Chum

Sockeye

Chinook cutthroat

Steelhead

Photo by Vali Eberhardt

Photo by Hans Berge

Photo by Geoff ClaytonPhotos by Phil Simpson Photo by Rodney Hsu

PACIFIC SALMON ARE MARINE FISHES

NEARSHORE

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General Functions of Shallow

Nearshore Habitats for Juvenile

Salmon• Feeding

• Migration

• Refuge from predators

• Physiological transition from

freshwater to saltwater.

• CWT Chinook

were caught

from 22

different

hatcheries

representing

13 different

Watersheds

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Diet

Overall diet composition based on prey

ecology for juvenile Puget Sound Chinook

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Numerical Gravimetric Numerical Gravimetric

% C

om

positi

on

supralittoral/marshterrestrial riparian

marine benthic/epibenthic

marine planktonic/neritic

other

plant matter

2001

n=410

22 empty

70-320mm

mean 112.0

2002

n-409

9 empty

72-354mm

mean 107.2

Leaf Hopper

Polychaete

Crab Larvae

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From the Daily Olympian

BREAK

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Switching Gears

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• Overwater Structures

• Clearing and Grading

• Non-native species

•Armoring

•Filling

•Dredging

•Pollution

Human Influences

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Adapted from Collins

and Sheikh 2005

Currently, King County has less than 2% of

its historic estuarine wetlands left

KVI or Point Heyer, Vashon Island,

photo from WADOE

Historic Elliot Bay Shoreline

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1977

2000

Filling• Loss of

shallow

water habitat

• Loss of

riparian

functions

• Changes in

hydrology

• Elimination

of spawning,

rearing and

refuge

habitat

Overwater Structures

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75

MedicineReturn.org

What is Shoreline Armoring?

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Shoreline Armoring

in the Green-

Duwamish

Watershed

• 92 miles shoreline

• Total=63% is armored

– Mainland is 80%

– Islands are 50%

Why do we

care?

85

Blocks feeder bluffs from feeding beaches

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Trees Overhanging the Shoreline in Relation to

Shoreline Armoring

0

5

10

15

20

25

Overhanging Not Overhanging

Mil

es Unarmored

Armored

41%

6%

10%

43%

From Higgins et al. 2005

Sand Lance &

Surf Smelt Spawning Area

No Spawning Area

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Wood Distribution in Relation to Shoreline Armoring

0

10

20

30

40

50

60

None LWD Drift Logs

Mil

es Unarmored

Armored

64%

15%

21%

8%

56%

14%

0.5%

15%6.5%

Wood Distribution Along WRIA 9's

Marine Shorelines

0

10

20

30

40

50

60

70

None LWD DRIFT

Mile

sUnarmored-LWD

Unarmored-Drift logs

64%

15%

21%

Marine View Park

SW Vashon Island

Marine

Shorelines of King County

From Higgins et al. 2005

Recent UW Study

89

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Recent UW Study

From recent UW Study

91

=

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92

=

From recent UW Study

93

≠

From recent UW Study

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Armored-is lighter

Natural is bold

Adapted from Rice 2006

Armored-is lighter

Natural is bold

Adapted from Rice 2006

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Armored-is lighter

Natural is bold

Adapted from Rice 2006

Armored-is lighter

Natural is bold

Adapted from Rice 2006

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Armored-is lighter

Natural is bold

Adapted from Rice 2006

Armored-is lighter

Natural is bold

Adapted from Rice 2006

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ARE THERE ALTERNATIVES

FOR HARD SHORELINE

ARMORING?

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Marine Shoreline

Design Guidelines

Includes lots of useful info

• Basic Puget Sound Geology

• Site assessment

• Risk assessment

• Coastal Processes Assessment

• Alternatives to bulkheads

User Friendly Version in Back

Bulkhead Alternatives?

From the Marine Shoreline Design Guidelines

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Relocate-back

From the Marine Shoreline Design Guidelines

Relocate--up

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Wood Placement

Photos from Coastal Geologic Services

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Upper Beach Nourishment

Maury Island

Before wood sill and

Beach Nourishment

Weaverling Spit

Photo from Coastal Geologic Services

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AFTER wood sill and

Beach Nourishment

Photo from Hugh Shipman

Pre-Project

From Josh Latterell

Year 1

Removal & Partial Nourishment

Dockton Park, Maury Island

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Samish Beach- before nourishment

From Jim Johannessen

Samish Beach- after nourishmentFrom Jim Johannessen

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Beach Nourishment with sill

Seahurst Park, Burien

Pocket beach

Olympic Sculpture Park

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QUESTIONS?

Living On, Above, or

Below Coastal Bluffs

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Shannon and Wilson

Landslide Study for the

City of Seattle, 2000

Landslides

in Seattle

Most common human contributions to landslides:

• Inappropriate vegetation management

• Inappropriate water management

• Inappropriate fill/debris placement

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Surface Water

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Dolphin Pt. Vicinity

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Ground Water

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Interceptor

Trenches

Horizontal/Directional Drilling

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Rain garden, an Element of “Low Impact

Development” (LID). Photo curtesy WA DOE

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A FEW WORDS ABOUT FILL

AND DEBRIS PLACEMENT

Fill placement on slopes.

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Typical backyard fill failure

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Shallow Landslide resulting from

disposal of yard waste on a steep

slope. Photo by Dan McShane

Lawn

Landslide path

Wad of soil and yard waste

A FEW WORDS ABOUT

BULKHEADS AND SLOPE

STABILITY

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Homes destroyed in 1997 Perkins Lane

landslide on Magnolia Bluff in Seattle. Photo

Hugh shipman WA DOE

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Great Northern Seawall

Construction, 1906

19671929

Present

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2011

20101997

2013

Bluffs and erosion

• Bluffs are inherently unstable

• Humans can reduce or increase that

instability:

– Surface and groundwater

– Adding fill/debris

– Shoreline armoring

– Changes to vegetation