Documents

Supplemental EA #10, End of Emergency Deviatio
Final FONSI - September 25, 2022
Final SEA - September 25, 2022
Appendix A - 2016 USFWS BO Update
Appendix B - 2000 USFWS BO and 2005 Amendment
Appendix C - 2008 USFWS Letter of Concurrence
Appendix D - USFWS Species List
Appendix E - Interested Parties Contacted
Draft FONSI – May 26, 2022
Draft SEA – May 26, 2022
 
Supplemental EA #9, Vegetation Mitigation
Final SEA/FONSI - November 4, 2022
 

Supplemental EA #8, USFS Visitor Center
To All Interested Parties Letter - April 12, 2021
Draft SEA - April 12, 2021
Final SEA - June 28, 2021

Isabella DSMP Timeline
Isabella DSMP Timeline as of Oct. 8, 2019

 

Contact Information

For more information on the
Isabella Dam Safety Modification Project
please contact us
at the following:

Phone:
916-557-5100

Email:
isabella@usace.army.mil

Mailing Address:
U.S. Army Corps of Engineers
Sacramento District
Isabella Dam Safety Modification Project
1325 J Street, Room 1513
Sacramento, CA 95814

Isabella Lake Dam Safety Modification Project

Lake Isabella is located 40 miles northeast of Bakersfield, Kern County, California, and consists of an earthfill main dam and auxiliary dam across the Kern River and Hot Springs Valley, respectively. The dam was authorized under the Flood Control Act of 1944 and construction was completed in 1953.

The reservoir provides flood-risk management, irrigation and recreational benefits. With more than 300,000 people living and working below the dams, primarily in the town of Lake Isabella and the city of Bakersfield, the U.S. Army Corps of Engineers began a dam safety modification study in 2006 to address seismic, hydrologic (potential over-topping during an extreme flood event) and seepage issues at the dams.

Following the signing of the Record of Decision in December 2012, USACE entered the Pre-Construction Engineering and Design phase of the project, and from 2013 to 2016, focused on design improvements to the existing dams and the relocation of U.S. Forest Service buildings located in the excavation footprint. Construction of the USFS warehouse/administrative buildings in Kernville and the USFS fire station in Lake Isabella were completed in 2017.

In September 2017, USACE awarded a $204 million contract to Flatiron/Dragados/Sukut Joint Venture of Benicia, California, to construct the Phase II dams and spillways modifications. Phase II was substantially completed in 2022.

Ask a Dam Question

The hottest question at the moment ...

 What's the latest news regarding the permanent USFS Visitor Center site selection? 

The U.S. Army Corps of Engineers Sacramento District has completed the acquisition of the former Bank of America property in Lake Isabella for relocation of the U.S. Forest Service visitor center.

USFS selected the location at 6212 Lake Isabella Boulevard – the corner of Lake Isabella Boulevard and Nugget Avenue – in Lake Isabella as the preferred site for their new location after a rigorous USACE environmental study and planning process.

The former visitor center was displaced by construction of a new emergency spillway as part of the Isabella Dam Safety Modification Project and a temporary visitor center has been co-located with the USFS Lake Isabella fire station in the interim.

USACE continues to work closely with the Forest Service on design of the new facility and construction is expected to begin in 2024, with completion by spring 2025.

For more information, visit the Lake Isabella Visitor Center Webpage.

 What is a "Labyrinth Weir" anyway?

Construction of the new emergency spillway between the main and auxiliary dams will include a 28-foot-tall, roughly 1,300-foot-wide "Labyrinth Weir" at the top of the spillway. The zig-zag-patterned pseudo-dam is designed to help regulate water flow through the emergency spillway rather than to hold it back like the main and auxiliary dams are designed to do.

Check out this video of the model our team constructed at Utah State University's Water Research Laboratory in Logan, Utah, during the planning and design phase of the project. It allowed our engineers to review the final hydraulic design—including the Labyrinth Weir—before construction of the thing begins.

We want to answer your questions! If you’re curious about the process or have specific questions for us, please email us at Isabella@usace.army.mil.

News Updates

 Informational Public Meetings held Nov. 9-10 in Kernville, Lake Isabella

The Sacramento District held informational public meetings on Nov. 9 and 10 in Kernville and Lake Isabella to discuss recent construction progress on the Isabella Dam Safety Modification Project and a look ahead to Phase 3 of the project.

The District has achieved substantial completion of the dam and spillway modifications, which means the core safety features needed to improve the dam’s safety rating are complete. This is an important milestone toward our goal to reduce risk to downstream communities including the Bakersfield metro area. 

Slides from the meeting can be viewed here.

For further questions and project updates, please email isabella@usace.army.mil

 Virtual Public Meeting on Ending Interim Risk Reduction Measures

Public meeting for the Isabella Lake Dam Safety Modification Project Draft Supplemental Environmental Assessment for the End of Emergency Deviation, Kern County, California

The U.S. Army Corps of Engineers, Sacramento District will be holding a virtual public meeting on May 19, 2022, to discuss a new draft Supplemental Environmental Assessment (SEA) for the Isabella Lake Dam Safety Modification Project (DSMP). The SEA evaluates the environmental effects of ending the Interim Risk Reduction Measures that were put in place to restrict the reservoir elevation at Isabella Lake, Kern County, California, to 2585.5 feet (Isabella Project Datum; 2589.26 feet North American Vertical Datum 1988 [NAVD 88]) above mean sea level until the Isabella Lake DSMP is complete. This emergency deviation has generally kept lake levels 20 feet below the normal gross pool elevation of 2605.5 feet (2609.26 feet NAVD 88) since 2006. During normal operations, the gross pool elevation is reached when the water level in the reservoir is at the crest of the service spillway and generally represents the elevation where all flood storage in the reservoir is filled. The deviation was put in place to reduce risk to life and public safety until the Isabella Lake DSMP is complete. Ending the deviation will allow the lake to naturally fill depending on rainfall within the watershed.

Meeting will be held 4:00 to 5:00 pm, Thursday, May 19, 2022.

Meeting link: https://usace1.webex.com/usace1/j.php?MTID=m530b156329bbef8e93e5f2f9be59247b

Slides for meeting

Meeting number: 2761 771 5250

Password: XGt6EAFU?92

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+1-844-800-2712 US Toll Free

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 Public Review Process for Supplemental Environmental Assessment 10

The public comment period for the draft Supplemental Environmental Assessment #10 opened on May 30, 2022, and will end on June 14, 2022.  All comments received on the draft document will be considered and incorporated into the updated Final Supplemental Environmental Assessment, as appropriate.

Please submit official comments relating to this draft Supplemental Environmental Assessment to:

U.S. Army Corps of Engineers, Sacramento District
Attn: Yari Johnson (CESPK-PDR-P)
1325 J Street
Sacramento, CA 95814
 

Or by email to isabella@usace.army.mil

General inquires can be directed to the Public Affairs Office at (916) 557-5100.

 Lake Isabella Visitor Center Information

USACE hosted a "virtual" public meeting in April 2021, to discuss Draft Supplemental Environmental Assessment #8 as part of the visitor center site selection process.

The meeting included a presentation on the NEPA process and the proposed alternatives, followed by discussion with all attendees. The meeting was recorded and is available for viewing here.

The public review period for Draft SEA #8 ended on May 12, 2021. All comments received on the draft document were considered and incorporated into the final SEA, as appropriate. The Finding of No Significant Impact was signed and the final SEA was released on June 28, 2021.

For more information, visit the Lake Isabella Visitor Center Webpage.

 Isabella Dam Safety Modification Project Timeline

Here's the latest on the overall project timeline - 

 French Gulch Boat Launch Extension

Construction work to extend the interim boat launch at French Gulch to 2544 feet elevation is complete and will remain available - lake levels permitting - for the duration of the Isabella Dam Safety Modification Project. The interim ramp replaces Boat Launch 19, which is closed for the duration of the project.

The U.S. Forest Service now has operational control of the French Gulch facility and will determine appropriate seasonal opening and closing dates, if necessary, for the ramp.

Frequently Asked Questions

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What is the plan?

The project includes:

  • Sealing the Borel conduit through the auxiliary dam.
  • Raising the main and auxiliary dams 16 feet to minimize the risk of over-topping.
  • Adding a filter and drain on the downstream slope of both dams to increase stability.
  • Improving stability of the existing spillway.
  • Creating an additional 300-foot-wide emergency spillway.

Safety remains our #1 priority – we have to reduce the risk from a potential failure for the people living below these dams. We feel this is the best way to do that.

 

What will happen to the Borel Canal now that USACE has acquired the easement through the Auxiliary Dam?

The Corps acquired the Borel easement from Southern California Edison in September 2018. The easement is that portion of the Borel Canal that runs immediately upstream, through (the conduit), and immediately downstream of the Auxiliary Dam. All other portions of the canal, upstream and downstream, are not on Corps property or our project area and, therefore, we have no authority to determine what is done with those portions of the canal.

The Corps has sealed the conduit through the Auxiliary Dam with concrete and filled those portions of the easement directly upstream of the dam with soil and rock. This work was completed in February 2019. As a result, the low-water restriction has been lifted and lake levels will be allowed to rise once again to restricted pool - 361,250 acre-feet - weather permitting.

Sealing the conduit has permanently cut off water supply to the Borel Hydroelectric Project. SCE will be responsible for determining any actions (including potential decommissioning) related to the canal and power station. SCE could also negotiate for another agency to take the lead in the decommissioning process.

Regardless of who takes that lead, other agencies would then partner together to ensure a smooth and appropriate process. For example, the California Public Utility Commission would be responsible for approving any change in power plant status to ensure local ratepayers and private landowners are not unfairly affected.

The Federal Energy Regulatory Commission, which permits hydropower production at Borel, would require that actions related to decommissioning be taken in a timely manner and that the canal not be left to create a safety hazard.

Finally, the US Forest Service and Bureau of Land Management, who own much of the land underneath the canal, would provide input into the final state of the canal.

As you can see, between USACE, FERC, CPUC, USFS, and BLM, there are several federal and state agencies working together with SCE and the public to put together the best environmental and economic plan for the fate of the Borel Canal, and regardless of the final decision, the public will have a chance to review the proposed action and provide comment.

 Why does it take the Corps so long to fix a dam?

Given the multiple purposes of this dam facility and the long-term benefits it provides, we require thorough analysis of any modification to assure public safety and benefits are not compromised by modification to the dam.

Dam analysis and designs are complex technical efforts. Risk assessments must be performed to understand the extent of a problem and to evaluate options to fix the dams. In this case the dam has multiple deficiencies that require correction which increases the time required to understand and to start the fixes.

We also take great effort to comply with the National Environmental Protection Act and the Endangered Species Act which does require significant time to assure that all requirements are met.

 When will the Corps make a decision on the permanent visitor center location?

USACE hosted a "virtual" public meeting in April 2021, to discuss Draft Supplemental Environmental Assessment #8 as part of the visitor center site selection process.

The meeting included a presentation on the NEPA process and the proposed alternatives, followed by discussion with all attendees. The meeting was recorded and is available for viewing here.

The public review period for Draft SEA #8 ended on May 12, 2021. All comments received on the draft document were considered and incorporated into the final SEA, as appropriate. The Finding of No Significant Impact was signed and the final SEA was released on June 28, 2021.

For more information, visit the Lake Isabella Visitor Center Webpage.

 

When will construction begin and how long will it take?

Phase I is already complete. Phase I included relocation of the USFS fire station in Lake Isabella and the USFS administrative building in Kernville, and construction of an interim boat launch at French Gulch to replace Boat Launch 19 until the project is complete in 2022. Once the project is complete, Boat Launch 19 will be reopened.

Phase II construction began in October 2018. Phase II includes 16-foot raises to both the Main and Auxiliary Dams, along with improvements to both dams and the existing Service Spillway; and construction of a new 1,500-foot-long, 300-foot-wide, and 100-foot-deep Emergency Spillway where the former USFS fire station and USACE operations office once stood between the Main and Auxiliary Dams. 

The project is expected to be complete in 2022.

 How do I get a job working on the Isabella Lake Dam project?

The workforce on this project will vary throughout the life of this project. Our prime contractor is responsible for hiring any work force needed to complete the job.

You can reach out to the contractor directly -

Flatiron/Dragados/Sukut Joint Venture
2959 Eva Ave
Lake Isabella, CA, 93240
833-640-1010

More information regarding project contracts can be found in the “Contract Opportunities” section below.

Contract Opportunities

No contract opportunities at this time. Please visit the Isabella Archive page for past contracts.

Recreation and Water Levels

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 Recreation at Lake Isabella - managed by U.S. Forest Service
The Isabella reservoir offers fishing, boating, water sports, camping, and picnicking. Close proximity to Los Angeles and Bakersfield makes this lake a popular yearround vacation spot for southern Californians. The lake is one of the state’s most popular windsurfing areas; reliable afternoon winds, from 35-50 miles an hour, create ideal conditions for intermediate to advanced windsurfers. Enjoy shoreline camping and day use activities at Auxiliary Dam, Old Isabella Road, or South Fork Recreation Area with the purchase of a Southern Sierra Pass or other Interagency Pass. South Fork Wildlife Area, one of the most extensive riparian woodlands remaining in California, provides fishing, hunting, canoeing, and hiking opportunities; no developed recreation facilities are located here. When operating on the lake, every boat, personal watercraft, and sailboard must display a permit from Kern County. These permits may be obtained at any lake marina or at various locations throughout the Kern River Valley. Be sure to check for required safety equipment.
 Recreation passes and permits

More information on Annual, Senior, Access, Volunteer, and the Southern Sierra Passes including Fee-Free Days in 2017 can be viewed here: https://www.fs.fed.us/visit/passes-permits.

Information is also available for Campfire Permits, River Permits, and Wilderness Permits at the same website. For more information, please contact the U.S. Forest Service at (760) 376-3781.

 Local weather and webcams at lake
Weather information, including current temperature, wind speed, rainfall and humidity, as well as live weather webcams around Lake Isabella can be viewed here: http://webcams.lakeisabella.net/ 
 Upcoming events
From farmer's markets to firework displays, Lake Isabella is full of community events. For more information on events, visit: http://www.lakeisabella.net/events/ 
 Current water levels

Current pool levels, elevation, inflow and outflow levels for Lake Isabella can be viewed here: http://www.spk-wc.usace.army.mil/fcgi-bin/hourly.py?report=isb

 Campground information
Information on developed campgrounds at Lake Isabella, managed by the U.S. Forest Service, can be viewed here: http://go.usa.gov/x9s5G 
 Water safety tips
  • Water safety tips from the Kern County sheriff's office can be viewed here.
  • Free loaner life jacket program information can be viewed here.