1.
Study Authority: The Puget Sound Nearshore Restoration
Project was initiated as a Corps of Engineers Civil, Title
1 General Investigation study under Public Law 106-60 (29
September 1999). This authority states:
The
following appropriations shall be expended under the direction
of the Secretary of the Army and the supervision of the
Chief of Engineers for authorized civil functions of the
Department of Army pertaining to rivers and harbors, flood
control, beach erosion, and related purposes.
General
Investigation funds are used for the collection and study
of basic information pertaining to rivers and harbors, flood
control, shore protection and related projects, restudy
of authorized projects, miscellaneous investigations, and,
when authorized by laws, surveys and detailed studies and
plans and specifications of projects prior to construction.
2.
Study Purpose: This report is a preliminary
analysis to determine if there is a federal (Corps) interest
in pursuing a feasibility study related to ecosystem restoration
in the nearshore environments of central Puget Sound. Once
restoration opportunities have been identified, the Corps
will work with local governments to determine which measures
and/or projects warrant further study effort in the feasibility
phase. For those potential projects, a Project Management
Plan (PMP) will be developed to conduct further feasibility
studies, and a Feasibility Cost Sharing Agreement (FCSA)
will be coordinated with the current local sponsors: King
County, and City of Burien. The primary area of consideration
is to address environmental restoration projects in the
nearshore environment of central Puget Sound. This analysis
is in accordance with the guidelines of Section 905(b) of
the Water Resources Development Act (WRDA) of 1986.
3.
Location of Study, Non-Federal Sponsor and Congressional
Districts
a)
The study area is located in the nearshore environment
of central Puget Sound in Washington State (Figure 1).
Possible restoration sites include:
1.
Shilshole Bay at the mouth of the Hiram Chittenden Locks
within the City of Seattle in King County;
2.
Seahurst Park in the City of Burien in King County;
3.
Dumas Bay in the City of Federal Way in King County;
4.
The nearshore coastline of Kitsap County;
5.
The nearshore coastline of King County, north of the
City of Seattle; and
6.
A series of programmatic projects including but not
limited to: restoration of estuaries, creation of wetlands,
rehabilitation of public abutments, softening of beach
fronts along private properties, and utilization of
slide material for use as source material into the Puget
Sound nearshore.
b)
The current non-Federal sponsors for the feasibility phase
of the study are King County, and the City of Burien.
In addition, both Kitsap and Island County and the City
of Seattle have expressed interest in the GI study, and
also may participate as local sponsors at a later date.
c)
The study area lies within the 1st, 6th,
7th, and 9th Congressional Districts.
4.
Discussion of Prior Studies And Existing Water Resource
Projects: The only previous studies done in the proposed
project areas have been associated with the Lake Washington
Ship Canal and the Hiram A. Chittenden Locks.
a) The Lake Washington Ship Canal. This project
was completed in 1916. The authorized project purpose
is navigation. The 8-mile long Lake Washington Ship Canal
links Puget Sound with fresh waters of Salmon Bay, Lake
Union, and Lake Washington. The Hiram A. Chittenden Locks
provide the navigable connection between salt and fresh
waters and controls the elevation of the Lake Washington
drainage basin to Puget Sound. Fish passage was provided
to mitigate for the loss of a stream to the project. The
fish ladder and locks enable adult anadromous fish passage
from salt to fresh water. A movable saltwater barrier,
located in the large lock, reduces saltwater intrusion
into Lake Washington during lock operations. The saltwater
drain located near the upstream end of the large lock,
returns much of the saltwater to Puget Sound via the original
spillway outlet located adjacent to the small lock and
through the fish ladder as attraction flows.
b) The Lake Washington Basin Restoration Study.
This current feasibility study is evaluating two water-related
issues in the greater Lake Washington Basin, which includes
Lake Sammamish, Lake Washington, and the Cedar River.
These issues are: improved salmonid migration and survival
at the Hiram A. Chittenden Locks through water conservation
and the modification of facilities, and the creation of
specific habitat improvements throughout the basin for
fish and wildlife. The listing of Puget Sound chinook
and Puget Sound bull trout as threatened species has strengthened
the need for specific habitat projects in the basin.
c) The Green Duwamish River Ecosystem Restoration
Project. The final feasibility report recommended
45 site specific and programmatic restoration sites in
the Green Duwamish River Basin. The recommended sites
were selected to address several limiting factors within
the Green/Duwamish River basin. The sites vary from stream
restoration projects high up in the basin to habitat restoration
in Elliot Bay at the bottom end of the river system. WRDA
2000 authorized $115 million for implementation of this
project over a 10-year timeframe.
5.
Plan Formulation:
(a)
Identified Problems: The proposed study would evaluate degradation
and loss of estuarine and nearshore habitat necessary to
the support critical fish and wildlife populations in the
central Puget Sound environment.
Historic
and current development along the Puget Sound shoreline
has resulted in a significant loss in estuarine and nearshore
habitats. The Washington State Department of Natural Resources
estimates that almost 80% of the original eastern nearshore
habitat of Puget Sound’s central basin (King, Pierce,
and Snohomish counties) has been modified through the construction
of bulkheads and docks, filling of intertidal habitat, and
removal of shoreline vegetation. Changes in physical structure
have resulted in losses which include loss of shade, reduction
in leaf fall, which limits terrestrial food sources and
nutrient inputs; lowering of the beach profile; coarsening
of beach sediment; narrowing of the beach; loss of area
through dredging and filling; and the alteration of groundwater
flows. The direct link between physical conditions and habitat,
and habitat and biological resources have resulted in significant
impacts to critical fish and wildlife resources, including
habitat that supports all species of salmonids. Remnant
habitat patches have now become critical support features
to remaining fish and wildlife populations, including two
threatened salmonid species (chinook salmon and bull trout).
There
are several factors that effect the character of the nearshore
and its related habitat functions. Factors include the extent
of armoring, structures within the nearshore environment,
sources of sediments, the extent of past modifications,
and littoral drift patterns. The needs and projects within
the Puget Sound nearshore specifically relate to shoreline
process restoration or rehabilitation. The project would
focus on the following types or needs:
-
Restoration of historic shoreline processes;
-
Beach nourishment;
-
Removal of armoring or structure setbacks;
-
Alternative ‘processes friendly’ erosion protection
measures; and
-
Sustainable measures.
Review
of past restoration projects clearly demonstrates the benefits
of creating and/or restoring functioning estuarine habitat
to the nearshore environment. This investigation would identify
restoration projects intended to maximize estuarine and
nearshore functions.
Existing
Conditions
Existing
studies have documented a 73 percent decline in the area
of Puget Sound covered by intertidal salt marshes. Nearly
all of this loss is associated with modifications of river
deltas within major urban areas. Direct loss to nearshore
environments outside of major river deltas has not been
as well documented. Additionally, the Washington State Department
of Natural Resources estimates that one-third of Puget Sound’s
shoreline – approximately 800 miles – has been
modified by human development. Central Puget Sound, with
the basin’s highe
