This
report documents an appraisal-level evaluation of raising Upper Klamath Lake in
South central Oregon. The lake is the State’s largest freshwater lake and is a
principal
storage feature of the Klamath Project. The Klamath
Project provides water for irrigating approximately 240,000 acres in the Klamath
Basin in south-central Oregon and northern California. The Klamath Project was
authorized for construction in 1905, and work began shortly thereafter. In 1921,
Link River Dam was constructed at the south end of the lake, near the city of
Klamath Falls, to provide regulation of the lake.
The
listing of fish species as threatened or endangered, and the Federal
responsibility to protect Tribal trust assets, have placed increasing demands on
the limited water supply of the Klamath Project and reduced its flexibility to
meet demands. There is an immediate need to increase water supplies and improve
the timing of their availability to improve fish and wildlife habitat and water
quality.
The
Bureau of Reclamation (Reclamation) began the Klamath Basin Water Supply
Initiative (Initiative) in 1996 to identify options for increasing water
supplies in the Klamath River Basin. The Initiative is a joint effort
partnership of Reclamation, the Klamath River Compact Commission, the California
Department of Water Resources, and the Oregon Water Resources Department. The
Initiative identified 96 options for increasing water supplies and recommended
44 for further study, including raising Upper Klamath Lake.
The
evaluation documented in this report considers increasing the maximum operating
level of Upper Klamath Lake by 2 feet by raising Link River Dam. Two options are
described: (1) raising existing levees around the lake to contain the
lake within its current surface area and (2) allowing the lake to spread and
flood adjacent lands.
Option
1 constrains the higher water surface elevation to the current shoreline.
Modifications would be provided to protect all existing land, roads, and
structures surrounding the lake.
A 2-foot-high parapet will be constructed on top of the dam to accommodate the higher water level.
Major
construction activities include:
_
Eight sections of new seawall, totaling 6.6 linear miles
_
Modifying 14 sections of existing dikes with roads, totaling 44.3 linear miles
_
Modifying 10 sections of existing dikes without roads, totaling 25.2 linear
miles
_
Two sections of new dikes with roads, totaling 1.9 linear miles
_
Three sections of new dikes without roads, totaling 2.7 linear miles
_
Armoring two sections of existing dikes, totaling 3.5 linear miles
_
Raising one bridge and county and local roads at seven locations, totaling 1.3
miles of roads
_
Raising 2.5 miles of a State highway
_
Rehabilitating 126 private residences (relocating septic tanks, providing
foundation drainage, and landscaping)
_
Rehabilitating headworks and intake structures at 10 locations
_
Relocating an existing boat dock
The
estimated cost of Option 1 is $125 million.
Option
2 does not protect structures and property, but, instead, allows the lake to
spread beyond the current shoreline and flood adjacent lands. Existing dikes
will be breached, and existing roads that would otherwise be inundated will be
raised. Either existing headworks and water intakes at various locations will be
retrofitted for the higher water surface elevation, or the associated facility
will be purchased. Link River Dam will be modified as in Option 1.
Major
construction activities include:
_
Breaching (every ¼ mile) 14 sections of existing dikes with roads, totaling
44.3 linear miles of dikes
_
Breaching 10 sections of existing dikes without roads, totaling 25.3 linear
miles of dikes
_
Armoring 3.0 linear miles of an existing dike
_
Raising one bridge and county and local roads at three locations, totaling 0.6
mile of road.
_
Raising 2.5 miles of an existing State highway
_
Rehabilitating headworks and intake structures at nine locations
_
Relocating an existing boat dock
The
estimated cost of Option 2 is $129 million, including $113 million for the
acquisition of private land and structures.
Raising
Upper Klamath Lake 2 feet will increase storage by approximately 170,000
acre-feet, or about 25 percent. Winter flood flows, which are presently spilled
to the Klamath River and not available for project use, will be stored and made
available to help meet water needs for endangered species, Tribal trust
resources, agricultural contractors, and national wildlife refuges. Future
operation of the enlarged lake will be contingent upon acquisition of
appropriate rights to divert and store additional water in the lake and may
require filing an application for the appropriation of additional water with the
Oregon Water Resource Department.
Costs
associated with implementing either Option 1 or Option 2 are significant. In
addition, implementing either option will have both positive and negative
impacts on the natural and human environment.
Several
engineering studies are recommended. These include:
_
Estimating quantities, properties, and availability of embankment and riprap
materials, and identifying their locations (quaries)
_
Constructing a modified dike test section to assess construction methodology and
performance of rockfill protection
_
Using detailed aerial topography (maximum 1-foot contours) of the Upper Klamath
Lake shoreline to better define existing features and required improvements
_
Conducting a comprehensive survey of all shoreline structures to provide a
better estimate of the work required and associated costs
_
Inspecting existing dam gates and concrete bulk heads to determine if additional
modifications are required for the higher reservoir water surface.
_ Developing site-specific, cost-effective alternatives to the proposed shore protection features
_
Identifying and securing suitable rights-of-way
Recreation
facilities need to be analyzed in more detail to determine impacts and
associated protection, relocation, and modification costs. A user survey and
appropriate mapping of all recreational facilities has been initiated to
determine existing recreation use levels and assist in the analysis of potential
impacts.
A
detailed hydrology study demonstrating that unappropriated water is available to
fill the additional storage in Upper Klamath Lake is recommended. Better
descriptions of area-elevation-capacity relationships and evaporation and
transpiration losses will also be needed.
The
following environmental studies are recommended:
_
Develop detailed topographic information for the entire lake and surrounding
area to predict the extent of flooding and potential vegetation changes
_
Develop topographic mapping in 1-foot increments to predict effects on wetland
vegetation
_
Determine potential stream flow changes below Link River Dam and potential
benefits to threatened and endangered fishes
_
Determine impacts to upland areas that would be inundated by the higher
reservoir water surface elevations.
The
following economic studies are recommended:
_
Determine all costs (e.g., planning, design, construction, mitigation, and
operation, maintenance, and replacement)
_
Determine benefit/cost
Early
development and implementation of a public involvement plan will be essential to
a feasibility study. Various studies to identify and analyze social impacts and
impacts to
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