Questions From Public Meeting, Nov. 14th, 2024

1. How much water can be stored safely in El Vado reservoir right now?
   Reclamation is currently working to identify how much water the reservoir can safely store before construction resumes. This is being done through a "first-fill" test which began in October 2024. Because the water surface has been low for several years during previous construction, the performance of the dam is being evaluated by checking physical parameters as the water level incrementally rises. We anticipate that we will know more about storage limits prior to the 2025 runoff.
2. Why was construction stopped?
   Construction on the preferred seepage reduction alternative started in 2022. During the 2022 and 2023 construction seasons, there were several issues found with the grouting behind the dam's steel faceplate as part of the seepage reduction work. The grouting caused further deflection and deformation to areas of the steel faceplate and caused damage to the underlying restraint structures. Reclamation changed grouting specifications, procedures, and grout mixes to improve and mitigate these issues, but despite these adjustments, the deformation and deflection concerns remained and were anticipated to worsen in time. This led to the decision to stop construction and further analyze alternatives for addressing seepage through the dam.
3. Is it possible for spillway construction to proceed?
   After we have determined the path forward with necessary repairs to the dam, we will better understand our options for proceeding with the spillway construction. There are multiple options being considered for repairing the dam that could impact the spillway differently. Therefore, it is necessary to hold off on the spillway construction until we have determined the path forward with the embankment repairs.
4. When was the last sediment survey completed at El Vado?
   The most recent sediment survey at El Vado was completed in 2018. An updated sediment and reservoir survey is being scheduled for 2025. It is critical to regularly monitor sediment with surveys because they tell us the actual current storage capacity in a reservoir, how much sediment has accumulated in the reservoir over time and identifies potential areas of concern where too much sediment may be accumulating. The accumulation of too much sediment near some of the dam's features could cause problems if unresolved and too much sediment buildup in the reservoir also negatively impacts overall storage capacity. Knowing this info better informs our research and ability to discuss potential solutions with our partnership organizations.
5. As far as Reclamation is aware, are these problems unique to El Vado? Have they occurred at other steel faceplate dams?
   El Vado is one of the few (less than 10) steel-faced dams that still exist in the world. The geographical locations of dams, their surrounding environments and their use are contributing factors to their durability and sustainability over time. Though the steel faceplate has served its purpose for nearly 100 years, some of the maintenance work needed was predictable, while the severity of degradation was not foreseen by engineers familiar with this type of structure.
6. Will the storage restrictions be changed or eliminated?
   The storage restrictions are currently being re-evaluated. It is anticipated that some level of storage restriction will be necessary in the reservoir until the project is complete. When construction begins on the selected alternative, the reservoir will have to be drawn down again to access the dam for repairs.
7. When is construction anticipated to begin?
   We anticipate that construction on an identified alternative could begin within 3 to 6 years. Reclamation is working with a team of dam safety experts to develop and select a preferred alternative for addressing the Safety of Dams issues, and a new environmental compliance process will be required. After that process, we will then design and contract the work to implement the preferred alternative.
8. With new alternatives, what is being done to reduce the risk to the dam and public?
   The safety of the public and our ability to store and make water deliveries is our paramount concern. As alternatives are developed and evaluated, we will continue to implement measures that reduce the risk to the dam and public. While we anticipate having these answers in the coming months, an alternative storage agreement is in progress between Reclamation, Albuquerque Bernalillo County Water Utility Authority and the Middle Rio Grande Conservancy District to allow storage of Rio Grande water in the water authority's allotted space in Abiquiu Reservoir for up to 10 years.

Safety of Dams Project Status

Around 2007, Reclamation first identified changes in seepage through the embankment and began a rigorous monitoring effort that included Issue Evaluations and Corrective Action Studies for observed dam safety issues at El Vado Dam. Those studies involved the evaluation of issues and risks to the public.

In 2017, based on the analysis and further information, Reclamation deployed its Safety of Dams Program to develop options and alternatives for addressing the risk of failure due to seepage and to reduce the risk of failure of the spillway. Reclamation, in collaboration with MRGCD and a team of consultants, decided to move forward with the least-cost, technically viable alternative: an impermeable geomembrane over the steel faceplate of the dam. Grouting was incorporated into the design to provide a stable backing for the steel faceplate to appropriately support the geomembrane.

The best value-lowest cost alternative was selected to reduce the risk from seepage through the embankment utilizing a combination of the existing steel faceplate and grouting behind the faceplate to support a geomembrane lining system. This alternative was anticipated to have a life of up to 75 years. A contract for the work was awarded in 2021 and work began in 2022.

Construction on the least-cost alternative commenced with grouting behind the steel faceplate. Grouting was extremely slow and bulging of the faceplate became a concern. In addition, the grouting was expensive as well as ineffective in creating a stable foundation for the steel plate. The condition of the plate was worse than anticipated. The structures intended to anchor the steel plate to the dam were found to be weakened or non-existent.

Given these developments, a re-evaluation of the progress to date and condition of the facility was undertaken. The additional assessment of the dam found that the steel faceplate and underlying supports are in much worse condition than originally known. On May 2, 2024, Reclamation, in consultation with its partners at MRGCD made the decision to discontinue grouting behind the steel faceplate at El Vado Dam and evaluate alternative solutions for reduction of seepage through the dam.

Reclamation worked with the contractor to develop a demobilization plan, which included leaving the dam in a safe condition.

Reassessment of design alternatives is currently in progress. This includes a drilling and testing program to evaluate the strength of the foundation materials beneath and around the dam. The final design of a permanent solution to the seepage issues will be dependent on the results of the field explorations.

The road across the dam, New Mexico State Road 112 (NM-112) is currently open but may be closed for short periods of time in the future to allow for construction work at the facility. Contact the New Mexico Department of Transportation (NMDOT) for plans and detailed information about the operations and potential closures of NM-112. NMDOT has jurisdiction for NM-112.

Reclamation has been coordinating repairs of NM-112 with NMDOT and plans to build two lanes across the crest of the dam as part of the Safety of Dams construction project.

GENERAL

• Contact New Mexico State Parks for plans and detailed information about the operations at the State Park. Reclamation is providing the State Park with updated plans and information about the construction project and water operations plans that may impact their management decisions.
• El Vado Reservoir stores water primarily for irrigation. The reservoir also provides recreational opportunities.
• Reclamation owns El Vado Dam and Reservoir. Reclamation operates El Vado Dam under an agreement with MRGCD.
• Los Alamos County (LAC) owns and operates a Federal Energy Regulatory Commission-regulated hydroelectric plant installed in El Vado Dam.
• The total maximum storage of El Vado Reservoir is about 200,000 acre-feet, which is used for native Rio Grande water for use by MRGCD and the six Middle Rio Grande Pueblos as well as San Juan-Chama (SJC) Project water for MRGCD and others.
• Storage and release of native Rio Grande water for MRGCD is subject to provisions of the Rio Grande Compact (Compact).
• Imported SJC Project water and water retained for the Six Middle Rio Grande Pueblos are not subject to provisions of the Compact that limit storage and release of water under certain conditions.
• Reclamation regularly performs exams of El Vado Dam as part of the Safety of Dams Program.
• Reclamation maintains an Emergency Action Plan for El Vado Dam and Reservoir and conducts periodic exercises of emergency operations with local government agencies to decrease agency response times and help protect public safety if there is an actual emergency.
• The channel capacity below El Vado Dam is approximately 4,500 cubic feet per second (cfs).
• Reclamation contracts with New Mexico State Parks to manage recreation at El Vado Reservoir.

STORAGE

• It is anticipated that some level of storage restriction will be necessary until the construction project is complete. Currently, the storage restrictions for the construction period remain in place (6,820.5 feet/~25,500 acre-feet). The level of safe storage for the facility and the public will continue to be evaluated. We anticipate that construction on an identified alternative could begin within 3 to 6 years. We also anticipate increasing storage availability as the construction project moves towards completion. Full storage likely will not be available until both the seepage reduction and spillway projects are complete.
• Unless under Compact restrictions, the plan for filling El Vado Reservoir is to store flows that are in excess of downstream requirements, such as those for Rio Chama water rights holders. In general, water is stored during the spring runoff for release later in the year when natural flows are lower.
• In a 1928 Act (Act of March 13, 1928, Chap. 291, 45 Stat. 312), Congress recognized the Six Middle Rio Grande Pueblos’ "prior and paramount" water rights for 8,847 acres of irrigated land, as well as domestic and livestock use. The Six Middle Rio Grande Pueblos are: Cochiti, Santo Domingo, San Felipe, Santa Ana, Sandia, and Isleta.
• The Secretary of the Interior designates space in El Vado Reservoir to retain water for irrigation on the Prior and Paramount lands of the Six Middle Rio Grande Pueblos. This water can be released if natural flows are insufficient to meet irrigation demand for the Prior and Paramount acreage.
• Under Article VII of the Compact, no storage of native Rio Grande water can occur in reservoirs constructed after 1929 upstream of Elephant Butte Reservoir, including El Vado Reservoir, when total useable Rio Grande Project water in storage at Elephant Butte and Caballo Reservoirs is less than 400,000 acre-feet. Usable water is defined in the Rio Grande Compact, with some exceptions.

RELEASES

• When either MRGCD or the Bureau of Indian Affairs (in the case of Prior and Paramount lands) determines that natural flow of the Rio Grande is insufficient to meet irrigation demands, they may call for a release from El Vado Dam.
• If water for irrigation on the Prior and Paramount lands of the Six Middle Rio Grande Pueblos is retained while under Article VII Compact restrictions, and remains unused during the irrigation season, it is released to Elephant Butte Reservoir after irrigation season and before the end of the year in which it was retained.
• Under Article VIII of the Compact, Texas may demand release of native storage (excluding the water for Prior and Paramount lands) up to the amount of New Mexico's accrued debit for under-deliveries to Elephant Butte Reservoir.
• SJC Project water released from Heron Reservoir for immediate use downstream of El Vado Reservoir is passed through El Vado Dam.
• When El Vado Reservoir spills, MRGCD has the option to spill SJC Project water belonging to others or to spill native water not held under terms of the Rio Grande Compact.
• Releases from El Vado Reservoir occur in a manner that is consistent with the following operational requirements and/or considerations:
• Native Rio Grande Basin water flowing into El Vado Reservoir, up to 100 cfs, is bypassed through the dam to meet demands of Rio Chama water rights holders.
• Reclamation aims to release about 100 cfs for fisheries below El Vado Dam from November to the start of runoff the following year.
• When possible and water is available, Reclamation supports the release of 400-600 cfs into the Rio Chama for boating on weekends and holidays from Memorial Day to Labor Day.
• Releases from El Vado Reservoir flow through the LAC hydroelectric plant within the maximum and minimum capacities of the plant. The plant operates as a "run of the river" facility, i.e., releases are not made for the sole purpose of generating power, but power may be generated from releases made for project purposes.

Contact

Please contact the Operations Group via e-mail at ResourceMgr@usbr.gov for additional information.