NASHVILLE, Tenn. (Aug. 23, 2023) – The U.S. Army Corps of Engineers Nashville District has extended the comment period for the draft Environmental Assessment and unsigned Finding of No Significant Impact for the revision of the 1998 Center Hill Dam and Reservoir Water Control Manual. Comments will be accepted until September 15, 2023.
The Environmental Assessment evaluates proposed operational changes, resource categories, and alternatives to assess potential effects of proposed water control manual updates.
The EA was made available for public review on August 2, 2023. The public review period is extended an additional 15 days.
Please send comments to CorpsLRNPlanningPublicCom@usace.army.mil. If you are unable to access an email account, you may send written comments to the address listed on the letterhead, ATTN: CELRN-PMP. Comments will be used to assess effects of the proposed action to the human environment. Your participation is greatly appreciated.
“Because of high public interest, this comment period is being extended to give more opportunity for stakeholders and the public to provide feedback on the agency’s tentatively selected plan,” said Valerie McCormack, chief, Environmental Section, U.S. Army Corps of Engineers Nashville District.
The proposed updates would incorporate recent historical data (1998-2022), new and rehabilitated structural features, watershed characteristics, communication networks, naming conventions, changes from previously approved EAs, and modern forecasting methods. These revisions are needed for current project operations and optimal management of the reservoir to achieve authorized project purposes. These updates are informational in nature and provide practical knowledge to Nashville District water managers. USACE evaluated three action alternatives in the Environmental Assessment. All three action alternatives would implement the following changes:
Hydropower Ramp Rates – Center Hill Dam has three hydropower turbines. The revised WCM would limit the ramp up to one unit in the first hour, then two units in the second hour. Ramp down would stay at two units per hour and would not change from the existing WCM.
Sluice Gate Operations – USACE would primarily use the non-orifice-equipped sluice gates for the purpose of flood risk management but could also be used, when deemed necessary by district water management, to improve water quality in the Caney Fork River to the maximum extent practicable while fulfilling authorized project purposes. Supplemental (non-flood risk management) flow through sluice gates would only occur as necessary to help target state water quality standards during times where their use would not limit USACE’s ability to meet authorized project purposes.
The three project action alternatives also propose changes to the minimum flow requirements at Center Hill Dam. The proposed minimum flow alternatives are Alternative 4 (Pulsed Flows—Existing Operational Conditions 2021-Present), Alternative 17 (Continuous Minimum Flow), and Alternative 23 (Seasonal Minimum Flows). The EA also evaluated Alternative 1 (No Action Alternative, NAA), which would result in no revisions to the 1998 Center Hill Water Control Manual.
USACE tentatively selects Alternative 4 as the Preferred Action Alternative. Alternative 4 has a pulsed minimum flow (one generator operating for one hour every eight hours). This alternative is consistent with the operational conditions since 2021. It has shown measurable improvements in the base flow of the Caney Fork River. Alternative 4 minimizes risk to hydropower production as compared to other action alternatives and could help the region meet increases in demand for reliable energy. While USACE identifies Alternative 17 as the Environmentally Preferred Alternative, it has the potential to limit hydropower production at the facility, particularly during critical summer months when energy demand is highest. In comparison to the No Action Alternative, the Preferred Action Alternative would continue to provide measurable improvements to the base flow of the Caney Fork River while not risking the ability of Center Hill Dam to meet hydropower demand.
This letter serves as a Notice of Availability for reviewing the draft EA and unsigned FONSI. The draft EA is prepared pursuant to the National Environmental Policy Act (NEPA) (42 U.S.C. §§ 4321-4370h), Council on Environmental Quality Regulations (40 C.F.R. §§ 1500-1508), and the Corps’ implementing regulation, ER 200-2-2, 1988 (33 C.F.R. § 230), Policies and Procedures for Implementing NEPA. Electronic copies of the documents can be found at http://www.lrn.usace.army.mil/Media/Public-Notices/Category/10561/project-planning-branch/.
(The public can obtain news, updates and information from the U.S. Army Corps of Engineers Nashville District on the district’s website at www.lrn.usace.army.mil, on Facebook at www.facebook.com/nashvillecorps and on Twitter at www.twitter.com/nashvillecorps. The public can also follow Center Hill Lake updates at www.facebook.com/centerhilllake.)