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Lakeside Living
Lake Washington/Cedar/Sammamish Watershed
Water Resource Inventory Area (WRIA)
8
Better than bulkheads
Bulkheads can create problems for salmon.
Do all lakeshore properties need
a bulkhead?
No. Protecting your shoreline depends on the amount of exposure, the
slope, length of fetch, how you use your shoreline – or how you would
like to use your lakeshore.
Why bulkheads are bad for salmon
Which types of bulkheads pose problems for salmon?
Vertical wall bulkheads cause the greatest environmental damage. These
can be straight concrete walls, gunnite applied over natural walls or
cliffs, wood walls, or rip-rap rock walls.
How do bulkheads create problems for salmon?
Bulkheads create deeper water with steeper gradient and a coarser bottom
substrate. Waves naturally travel aong a horizontal plane, dissipating
enegy over distance and as they hit shallower bottom, rocks, or shoreline
vegetation. But if a wave is suddenly stopped by a vertical wall, the
wave energy will increase in amplitude as it reflects off the wall and
it is added to by subsequent incoming waves. Instead of moving on a horizontal
plane, the wave energy moves up and down, and something has got to give.
This causees sediment at the base of the wall to get scoured out.
The finer sands are removed as the gravel gets eroded away and the bottom
substate gets coarser. The result is a beach that is much deeper and
steeper. Baby salmon need shallow beaches with a gentle gradient to
hide from predators that hunt in deeper waters. Bulkheads result in
a sudden drop off, which is bad for salmon and people of all ages.
The scouring action can also cause failure of the bulkhead as the
base erodes away. Vertical wall bulkheads can accelerate erosion
on neighboring properties if they are not tied into the same bulkhead
sytem. The result is a continuous hardening of the lakeshore.
Rip-rap rock walls can create problems by providing habitat for predators
that feed on young chinook. Fish that feed on juvenile salmon, such as sculpins and bass, hide in
the rock crevasses where they can ambush unsuspecting baby fish.
Photo and design: The Watershed Co.
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Better than bulkheads
Are there alternatives to vertical wall bulkheads to protect your
shoreline?
Yes, shoreline designers have come up with engineered
solutions to "soften" the shoreline, while still protecting
it from erosion. These features employ the use of terracing, large flat
rocks, shallow pools, logs, and vegetation to prevent erosion and provide
an attractive, usable shoreline.
Build a Beach
To reduce the slope where a vertical wall bulkhead exists, the shoreline
can be pulled back, creating a shallower grade. In its place a beach
cove is created.
Photo and design: The Berger Partnership
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Often the top of a vertical wall bulkhead forms a harsh
edge or is occupied by a section of lawn that is rarely used. This can be a dangerous place to golf or have small children play. The alternative
is a beach that may be more usable. By pulling the shoreline back, the
homeowner isn't really losing property but converting it to a new format,
which can be quite attractive and very functional, especially in terms
of improving access to the water. As the water along this modifed shore
will be shallower, it becomes easier and safer to access.
Alternatives to vertical wall
bulkheads can be better for fish
- Less turbulance.
Photo and design: The Watershed Co.
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- Shallower grade.
- Protection from predators.
- Finer sandy bottom.
- Increased food source.
Benefits for property owners
- Easier access to beach and water, especially nice if you have a
kayak or human-powered craft.
- Shallow gradient shore and water can be safer, especially if you
have small children.
- More usable shoreline with beach and cove.
- Reduced maintenance.
- Potential for increased property values.
- The pride and pleasure knowing that there are baby salmon rearing
off your shore.
Photo and design: The Berger Partnership
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Plants, logs, and rocks
Skillful shoreline designers and contractors can combine the use of
logs, rocks, and vegetation to stabilize the shoreline and create an
attractive lakeshore landscape.
High Beach Cove
The shoreline can be more useful for young fish and homeowners with
creation of a high beach cove.
Photo and design: Waterfront Construction
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