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During the ongoing engineering and design phase for Isabella Lake Dam upgrades, the Corps identified 12 properties downstream of the dam that will be impacted by construction. 

Impacted property owners have already been officially contacted or notified by a Corps real estate specialist as part of the process. There may be additional property owners contacted in the future, but everyone affected by this initial phase of acquisition has been contacted at this time. Until officially contacted or notified by a Corps real estate specialist, property owners are encouraged not to change, plan or do anything in anticipation of being contacted.

During the ongoing engineering and design phase for Isabella Lake Dam upgrades, the Corps identified 12 properties downstream of the dam that will be impacted by construction.

Impacted property owners have already been officially contacted or notified by a Corps real estate specialist as part of the process. There may be additional property owners contacted in the future, but everyone affected by this initial phase of acquisition has been contacted at this time. Until officially contacted or notified by a Corps real estate specialist, property owners are encouraged not to change, plan or do anything in anticipation of being contacted.

The storage and release of flood water in Isabella Lake is under the control of our Water Management Section, however, we have no influence over the operation of the reservoir outside of flood operations. During construction, the release of water will continue to be dependent on inflow, irrigation needs and downstream storage capacity.

We’re doing everything we can to minimize the impact to the public, with as little disruption as possible. We released a draft recreation report in February 2014 that further explores and identify options for mitigation to offset adverse effects on recreation including the needs for recreational flows in the lower Kern River. View the draft recreation report here

As a side note, rafting companies that operate above the reservoir would continue operations as normal and be unaffected by the dam safety modification project.

The Auxiliary Dam Recreation Area cannot properly accommodate flush toilets due to inadequate drainage fields there. The vault toilet replacements are preferred due to reduced maintenance costs and lower water use. New vault toilets are also engineered to better reduce odor. Cost benefit assessments are not conducted within the NEPA process, but will be evaluated in the decision process.

Some examples of the proposed vault toilets can be viewed here.

No. We initially considered wind turbines as a way to highlight the latest technology in meeting energy sustainability requirements, however, based on criteria of energy efficiency, cost, and overwhelming public input for visual preference, we have decided to go with solar panels.

The building energy sustainability requirement (Executive Order 13693) is that at least 10% of the building’s power needs shall be clean energy, accounted for by renewable electric energy and alternative energy. Solar panels will meet this requirement.

The Auxiliary Dam Recreation Area is planned to primarily be a temporary staging area that would be returned for recreation use after the project is complete. It will also serve as a secondary on-site borrow source for filter sand on the main and auxiliary dams should the excavation of the emergency spillway not be able to provide sufficient quantities. 

Other camping areas around the lake are not scheduled to be affected by the project, and the U.S. Forest Service would continue as the managing agency for these areas.

We recognize and appreciate the value of the public lands here, so Supplemental Environmental Assessment #4 was released in April 2016 to further explore and identify options for mitigation to offset adverse effects on recreation. Public participation was solicited to address concerns over the negative impacts of the project. View SEA#4 here.

We are working with the U.S. Forest Service and local community groups to further minimize the impacts to local events on the lake, campgrounds, boat launches, etc. The majority of the time the lake would remain under its current operation with the pool restriction, and recreation will still be permitted on the lake during construction. 

We are committed to working with the community, and one of the concerns we are hearing is about reducing the amount of time the lake elevation would be reduced. As a result, under the authorized plan, the lowered pool elevation for construction has been limited to a single four-to-six month window between October 2020 and March 2021.

This takes advantage of the natural low reservoir elevations during the fall and winter months when it is already being drawn down for flood control operation, minimizing impacts to recreation, water quality, fisheries, and socioeconomics, and further reduces the impacts over the entire construction period. More details resulting from this process were released in Supplemental Environmental Assessment #4 in April 2016 and are available here.

The current low water level is due to lower than average rainfall and snowmelt. The Corps is only responsible for directing releases during the winter months (Nov. 1 - Feb. 1) to maintain storage space for the rainy season and anticipated snowmelt. Downstream water users control the outflow based on irrigation demand the rest of the year. The Corps plays no role in those decisions.

The refinements that went into the authorized plan will reduce many of the anticipated construction-related impacts, but negative short-term impacts on property values may occur during construction.

Our assessment of potential project impacts to the local economy found both short- and long-term benefits associated with construction-related spending in the Kern River Valley and unrestricted reservoir operations upon completion of the project. 

Long-term economic improvement resulting from recreation, higher lake levels, employment opportunities, and lower safety risk would likely result in improved property values. These project benefits may serve to provide the Kern River Valley with greater long-term economic stability, which is a major factor in determining regional property values.

Not under the current dam safety modification study. Increasing of the storage capacity would require separate authorization and would require a different study.

The South Fork Delta sand borrow area has been eliminated as a sand source for the authorized plan. Sand will now be manufactured at the dam site utilizing waste materials generated from the emergency spillway excavation. This refinement has eliminated the largest contributor to short-term construction-related traffic and circulation impacts along Highway 178 within the Kern River Valley. The majority of the truck traffic is planned to occur onsite for excavation, processing, and fill placement to reduce impacts.

Highway trucks will still be required to meet all standards; therefore there should be no impacts to roads except for the everyday wear and tear that they are designed for. 

We have eliminated the original relocations of Highways 155 and 178. There will be some construction around Highway 155, but we will work to minimize the time and impact to local residents.

We understand the concern regarding the duration of construction and are doing everything possible to shorten completion dates. Currently, we are finalizing our costs and schedule for design and construction, and will have a more accurate reflection once that is complete. There are always unknowns associated with construction, but we are committed to minimizing any impacts that may arise. We will continue to refine the schedule to ensure efficiency in construction.

There are no guarantees in regards to funding. However with the continued support of the community and the “high risk” ranking of the dam, we will continue to express the need for timely funding to keep the project on schedule.

A downstream replacement dam at the auxiliary dam site was evaluated, but not selected based on increased cost, larger demand for materials, a longer construction schedule and increased air quality concerns based on the additional earthwork. This project won’t come cheap, but our duty is to modernize the dams by getting the most value for every taxpayer dollar, and that’s what we believe our identified plan does.
The Record of Decision allows for the official start of the next phase of the project and was signed at the Corps’ headquarters in Washington, D.C., by James Dalton, Chief of Engineering and Construction in December 2012. The ROD is a document that states what the decision is; identifies the alternatives considered, including the environmentally preferred alternative; and discusses mitigation plans, including any enforcement and monitoring commitments. Read more about the ROD here.
The estimated project cost is $400-$650 million.
In 2013, we entered the Pre-Construction Engineering and Design phase of our project. We still have a number of procedural tasks to complete in preparation for physical construction of the authorized plan. The highway relocations would have begun in 2014, however, that is no longer required for implementation of the authorized plan. The major components of construction will begin in 2017.
Under the preferred plan, the construction pool elevation has been limited to a single four-to-six month window between October 2020 and March 2021 in order to take advantage of the natural low reservoir elevations during the fall and winter months when it is being drawn down for flood control operation. This reduces the potential for dust impacts described in the draft environmental impact statement from lake lowering.

For the majority of the construction period, the lake will remain under its current operation with the pool restriction. Potential impacts from windblown dust can be effectively reduced to less than significant levels through the use of best management practices, which will be required. These practices are described in Section 3.3.3 of this final environmental impact statement and Section 3.5.4 of the draft EIS.

The Freedom of Information Act (FOIA) process is the best way to obtain documents that are not released for public review at a minimal cost (if any). Information regarding FOIA can be found here.

Investigations have shown that obtaining borrow materials from the lake bottom are not cost effective for filter and drain materials and would introduce other environmental concerns, such as water quality effects associated with lake lowering, and increased fugitive dust concerns.

Contract Archive

Opportunity Type Award Date
Construction - Phase II Award  Sept. 18, 2017
Construction - Admin Bldg./Warehouse Award July 28, 2016
Construction - Fire Station Award July 19, 2016
Materials Investigation Award
Apr. 4, 2014