Notice2025-06830
Chatuge Dam Safety Modifications
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
April 21, 2025
Issuing agencies
Tennessee Valley Authority
Abstract
The Tennessee Valley Authority (TVA) intends to prepare an environmental impact statement (EIS) under the National Environmental Policy Act (NEPA) to address the potential environmental impacts associated with the proposed modification of the Chatuge Dam Spillway, low-level outlet (LLO), and the dam embankment. Based on evaluations conducted between 2016 and 2022, TVA determined that the risk of uncontrolled releases due to spillway failure exceeds TVA's risk tolerance for dam safety.
Full Text
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<title>Federal Register, Volume 90 Issue 75 (Monday, April 21, 2025)</title>
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[Federal Register Volume 90, Number 75 (Monday, April 21, 2025)]
[Notices]
[Pages 16760-16761]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-06830]
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TENNESSEE VALLEY AUTHORITY
Chatuge Dam Safety Modifications
AGENCY: Tennessee Valley Authority.
ACTION: Notice of intent.
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SUMMARY: The Tennessee Valley Authority (TVA) intends to prepare an
environmental impact statement (EIS) under the National Environmental
Policy Act (NEPA) to address the potential environmental impacts
associated with the proposed modification of the Chatuge Dam Spillway,
low-level outlet (LLO), and the dam embankment. Based on evaluations
conducted between 2016 and 2022, TVA determined that the risk of
uncontrolled releases due to spillway failure exceeds TVA's risk
tolerance for dam safety.
DATES: The public scoping period begins with the publication of this
Notice of Intent in the Federal Register. To ensure consideration,
comments must be postmarked, submitted online, or emailed no later than
May 28, 2025. To facilitate the scoping process, TVA will be holding
in-person meetings in Clay County, North Carolina and Towns County,
Georgia. Additionally, TVA will hold two virtual public meetings. The
meeting locations, dates, and times will be posted on <a href="https://www.TVA.com/nepa">https://www.TVA.com/nepa</a>.
ADDRESSES: Written comments should be sent to Erica McLamb, NEPA
Compliance Specialist, 1101 Market Street LPE5S, Chattanooga, Tennessee
37402. Comments may also be submitted online at https://www.tva.com/
nepa or by email at <a href="/cdn-cgi/l/email-protection#a6c8c3d6c7e6d2d0c788c1c9d0"><span class="__cf_email__" data-cfemail="751b100514350103145b121a03">[email protected]</span></a>.
FOR FURTHER INFORMATION CONTACT: Erica McLamb by email to <a href="/cdn-cgi/l/email-protection#8fe1eaffeecffbf9eea1e8e0f9"><span class="__cf_email__" data-cfemail="610f041100211517004f060e17">[email protected]</span></a>,
by phone at (423) 751-8022, or by mail at the address above.
SUPPLEMENTARY INFORMATION: The EIS identification number is EISX-455-
00-000-1735297828. This notice is provided in accordance with the
National Environmental Policy Act (NEPA), as amended (42 U.S. Code
[U.S.C.] 4321 et seq.) and TVA regulations and procedures (18 CFR part
1318).
TVA's Chatuge Reservoir is located on the Hiwassee River. The
reservoir is approximately 13 miles long and extends southeast from
Chatuge Dam, located in Clay County, North Carolina, into Towns County,
Georgia. TVA operates the reservoir for many purposes, including flood
control, power generation, water supply, recreation, and augmentation
of downstream water flows. Chatuge Reservoir has a flood-storage
capacity of 62,600 acre-feet between an elevation (El.) of 1918 and
1928 feet.
TVA operates Chatuge Dam according to seasonal curves that guide
operations. The guide curve represents idealized target operations,
with a low point of El. 1915 in the middle of February when flood risk
is highest, and a high point of El. 1926 around Memorial Day. The flood
guide varies from El. 1918 in the winter to El. 1926 in the summer; all
volume above the flood guide is reserved for flood control storage.
Thus, in a year with normal rainfall, the water level in Chatuge
Reservoir varies about 10 feet from summer to winter to provide
seasonal flood storage. These operating levels were implemented
pursuant to TVA's Reservoir Operations Study.
During its program of dam safety risk assessments and integration
of dam safety industry findings, TVA concluded the chute slab of the
primary spillway at Chatuge Dam is in poor condition. TVA determined
that the potential for removal of one or more sections of the chute
slab during a rare flood event poses a dam safety risk outside of TVA
tolerances. TVA also investigated secondary sources of dam safety risk
associated with internal erosion through the dam. TVA judged that the
internal erosion risks were of lesser magnitude and within widely
accepted tolerable risk guidelines.
Beginning in December 2023, TVA implemented additional monitoring
and inspections of the spillway, repaired joints and sealed cracks in
the spillway slab and walls, and supplemented the existing Chatuge Dam
Emergency Action Plan for spillway failures to reduce risks. However,
the risk of spillway damage and failure remains higher than TVA's risk
tolerance. TVA proposes potential modifications to the Chatuge spillway
and low-level outlet works (LLOW) to reduce the risk associated with
Chatuge Dam. TVA is also considering modifications to the dam
embankment.
Project Purpose and Need
The purpose of the proposed action is to reduce risks to human
health and safety and improve flood control. The proposed action is
needed to ensure the continued safe operation of the Chatuge Dam for
hydrogeneration, flood control, water supply, and recreation.
Additionally, the proposed action is needed to ensure TVA can reliably
meet river flow obligations necessary to maintain aquatic habitat and
public water supply through improved reliability in the event of an
outage at the hydropower plant. The project would also ensure that TVA
can operate the Chatuge Dam and Reservoir in furtherance of TVA's
statutory mission to manage the Tennessee River system, its
tributaries, and its associated resources.
Preliminary Proposed Action and Alternatives
TVA anticipates the EIS will evaluate a No Action Alternative and
four Action Alternatives. Under the No Action Alternative (Alternative
A), TVA would not perform any modification of the
[[Page 16761]]
Chatuge Dam spillway, LLOW, or embankment, and would continue to
maintain these components in their current state. TVA would continue to
monitor and inspect the spillway, repairing joints and sealing cracks
in the spillway slab and walls as needed; however, the risk of spillway
damage and failure would continue to exceed TVA's risk tolerance.
To reduce the potential for spillway activation during the
construction for all Action Alternatives, TVA would draw down the
Chatuge Reservoir during the construction period. The maximum drawdown
of the reservoir would be to an elevation of 1,908 feet, which is 10
feet below normal winter pool. The estimated drawdown duration for each
alternative is described below; however, the drawdown could be extended
due to the need to maintain dam safety requirements, weather delays,
and unforeseen circumstances encountered during construction.
Alternatives B and C would include rehabilitation of the existing
spillway and replacement of the Howell Bunger Valve. The spillway would
be rehabilitated by reconstruction of the existing contraction joints
(Alternative B) or by installing a concrete overlay (Alternative C).
The construction and drawdown duration for Alternative B could be up to
eight years. The construction and drawdown duration for Alternative C
could be up to six years.
Alternative D would include construction of a new spillway and
abandonment of the existing spillway, replacement of the Howell Bunger
Valve, and dam embankment stabilization. The new spillway, located west
of the existing spillway, would be designed convey all the water from
the Probable Maximum Flood (PMF) which is 108,000 cubic feet per second
(cfs). Construction of Alternative D could last up to six years and
require the reservoir to be drawn down for up to four years.
Alternative E would include construction of a new gated spillway,
rehabilitation of the existing spillway, replacement of the Howell
Bunger Valve, and dam embankment stabilization. The new service
spillway, located west of the existing spillway would be designed to
pass a maximum discharge of 68,000 cfs through a gated crest. The
auxiliary spillway will maintain its current design discharge capacity
of 39,000 cfs. Construction of Alternative E could last up to seven
years and would require a reservoir drawdown up to five years.
Anticipated Environmental Impacts
The EIS will include a detailed evaluation of the environmental,
social, and economic impacts associated with implementation of the
proposed action. Resource areas to be addressed in the EIS include but
are not limited to air quality; aquatics; botany; climate change;
cultural resources; floodplains; geology and groundwater; land use;
noise and vibration; health and safety; soils; surface water; water
supply, socioeconomics; threatened and endangered species;
transportation; visual resources; waste; wetlands; and wildlife.
Measures to avoid, minimize, and mitigate adverse effects will be
identified and evaluated in the EIS.
Anticipated Permits and Other Authorizations
TVA's proposed action would require an Individual Permit under
Section 404 of the Clean Water Act; Section 401 Water Quality
Certification; a North Carolina Construction Stormwater Permit;
compliance with Section 106 of the National Historic Preservation Act;
and compliance with Section 7 of the Endangered Species Act; and other
applicable Executive Orders, local, Federal, and state regulations.
Public Participation and Scoping Process
Scoping is integral to the process for implementing NEPA and
provides a mechanism to ensure that issues are identified early and
properly studied; issues of little significance do not consume
substantial time and effort; the draft EIS is thorough and balanced;
and delays caused by an inadequate EIS are avoided. TVA seeks comment
and participation from all interested parties for identification of
potential alternatives, information, and analyses relevant to this
proposal.
Information about this project is available at https://www.tva.com/
nepa, which includes a link to an online public comment page. Comments
must be received or postmarked no later than May 28, 2025. Federal,
state, and local agencies and Native American Tribes are also invited
to provide comments. Please note that any comments received, including
names and addresses, will become part of the project administrative
record and will be available for public inspection. To facilitate the
scoping process, TVA will hold two in-person public open house meetings
and a virtual public meeting; see the project website for information
on the meeting dates and times.
EIS Preparation and Schedule
Following the scoping period, TVA may develop a scoping report that
will be published online. The scoping report will summarize public and
agency comments that were received and identify the projected schedule
for completing the environmental review process. Following analysis of
the affected resources, TVA will prepare a draft EIS for public review
and comment. One or more preliminary preferred alternatives may be
identified in the Draft EIS; however, the final decision on the
proposed modifications of the Chatuge Dam components (spillway, Howell
Bunger valve, and embankment) will be based on several factors
including the conclusions of the EIS, relevant federal and state law
requirements, engineering and risk evaluations, and financial
considerations.
TVA anticipates holding public open house meetings after releasing
the draft EIS. TVA expects to release the draft EIS in late 2025/early
2026 and a final EIS in late 2026/early 2027. TVA anticipates the
Record of Decision will be posted at least 30 days after the release of
the final EIS.
Authority: 18 CFR 1318.402.
Dawn Booker,
Senior Manager, NEPA Compliance.
[FR Doc. 2025-06830 Filed 4-18-25; 8:45 am]
BILLING CODE 8120-08-P
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</html>Indexed from Federal Register on April 21, 2025.
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