07-853. Intent To Prepare a Draft Environmental Impact Statement To Address Operational Changes at Center Hill Dam, Center Hill Lake, DeKalb County, TN, That Could Affect Pool Elevations

AGENCY:

Department of the Army, U.S. Army Corps of Engineers, DoD.

ACTION:

Notice.

SUMMARY:

The Corps of Engineers (Corps) is preparing a Draft Environmental Impact Statement (DEIS) to address operational changes at Center Hill Dam that could affect pool elevations. Center Hill Dam impounds Center Hill Lake in central Tennessee. The DEIS is necessary to provide National Environmental Policy Act (NEPA) compliance to address changes that could include, but are not limited to water quality, aquatic, riparian, and terrestrial habitat, recreation, water supply, flood storage, economics, hydropower production, and safety as a result of operating Center Hill Lake below normal pool elevations for extended periods of time. Several engineering studies have identified a heightened level of risk at Center Hill Dam due to increasing seepage problems under and around the dam. Since March 2005, the Corps has attempted to keep fall, winter and early spring lake levels from extreme rises due to high inflow. Seepage problems are made worse during continual high lake levels. As a result, the Corps plans to maintain lower lake levels, but still within the operations curve, to reduce pressure on the dam foundation, abutments, and rim walls until a permanent remedy is in place. A major grouting project to address the dam seepage is scheduled for the fall of 2007, followed by installation of a cutoff wall through the earthen portions of the dam and adjoining rim walls. Although not anticipated, the Corps may have to lower the lake pool significantly below the operating pool should seepage conditions worsen, or new information determine this action is necessary to reduce risk. This notice serves to initiate the NEPA process. The Corps plans to prepare and circulate a DEIS which serves to cover possible impacts due to extreme changes in lake levels that could occur during the repair of the dam's foundation and abutments.

DATES:

Written comments concerning issues to be considered in preparing the DEIS, must be received by the Corps of Engineers on or before March 28, 2007.

ADDRESSES:

Written comments on issues to be considered in the DEIS shall be mailed to: Joy Broach, Project Planning Branch, Nashville District Corps of Engineers, P.O. Box 1070 (PM-P), Nashville, TN 37202-1070. Comments may also be e-mailed to: [e-mail].

FOR FURTHER INFORMATION CONTACT:

For additional information concerning the notice, please contact Joy Broach, Environmental Team, [phone], Linda Adcock, Center Hill Dam Seepage Major Rehabilitation Project Manager, [phone], or Public Affairs Office, [phone].

SUPPLEMENTARY INFORMATION:

1. Center Hill Dam was designed in the 1930s, constructed in the 1940s, and impounded in the early 1950s. The dam was built on karst geology using accepted engineering practices of the day. Since the 1960s, seepage flows through the dam's right abutment and left rim wall have been monitored, and recently became a concern with increased seepage and development of turbid flows through springs below the left rim wall. Signs of seepage increase through the main dam and saddle dam foundations have also been noted. A formal risk assessment is currently being conducted to determine if a need exists to significantly alter lake levels outside the normal operations curve to reduce risk to people and property.

2. A comprehensive plan for repairs has been approved; however, these repairs will take a number of years to implement. Until the repairs are sufficiently complete, the Corps has determined that it is in the public's interest to operate Center Hill Lake at the lower range of the operations curve. Many rehabilitation alternatives were considered and potential impacts analyzed and are discussed in the following NEPA documents: Proposed Center Hill Dam Seepage Rehabilitation, Environmental Assessment, July 2005; and Proposed Center Hill Dam Seepage Rehabilitation, Environmental Assessment Supplement 1, March 2006. These documents have been included by reference. No significant environmental and economic consequences are anticipated under current dam repair plans; however, some water intakes and boat ramps may need to be extended for safe operation.

3. Though not expected, the Corps recognizes that if seepage conditions worsen, or new information determines that the lake elevations should be significantly changed to ensure the public's health, safety, and welfare; then the following resources could be significantly impacted:

(1) The cold-water fisheries both in the lake and tailwater;

(2) Water quality throughout the Caney Fork River and downstream in the Cumberland River;

(3) Federally listed threatened and endangered species;

(4) Designated uses of the waterway including fish and aquatic life, livestock watering and wildlife, irrigation;

(5) And economics including electric power production, municipal and industrial water supply, recreation, navigation, flood damage reduction, and disruption to communities, jobs, and other related factors.

4. Current Actions to Reduce Risk. Several actions have already been taken to reduce the risk. Prior to 2005, spring rains were captured in the reservoir to maximize downstream flood protection and hydropower generation. Beginning in March 2005, the pool was managed more aggressively to reduce inflow peaks and adhere more closely to the prescribed guide curves. In 2006, continuous surveillance was initiated at the dam. This involves providing patrols to monitor the dam, known seepage and trouble spots, and downstream areas. Currently, the Corps is conducting exploratory drilling to assess the limestone rock condition and key access points for future grouting activities. Additional coordination and exercises have been held with state and local emergency management agencies. These agencies will be provided flood inundation maps to help coordinate emergency evacuation planning. The Corps has improved its emergency notification procedures, increased instrumentation in, on, and around the dam, and conducted numerous public meetings to advise the public of problems with the dam.

5. A DEIS will be undertaken to review current actions taken and to consider other possible alternatives to reduce stress on the dam.

6. This notice serves to solicit comments from the public; Federal, State and local agencies and officials; Indian Tribes; and other interested parties in order to consider and evaluate impacts of these proposed activities. Any comments received by the agency will be considered in determining future operations. In the decision-making process, comments are used to assess impacts on public health and safety, endangered species, historic properties, water quality, water supply and conservation, economics, aesthetics, wetlands, flood hazards, floodplain values, land use, navigation, shore erosion and accretion, recreation, energy needs, food and fiber production, mineral needs, considerations of property ownership, general environmental effects, and in general, the needs and welfare of the people.

7. Activities proposed that may require a review under the guidelines promulgated by the Administrator, Environmental Protection Agency (EPA), under authority of Section 404(b)(1) of the Clean Water Act (40 CFR part 230) include fill placement for water intake extensions, boat ramp extensions, and other mitigation actions.

8. Other Federal, State, and local approvals that may be required for proposed work are as follows:

a. Section 401 water quality certification from the Tennessee Department of Environment and Conservation.

b. Coordination with the U.S. Fish and Wildlife Service for the Endangered Species Act and Fish and Wildlife Coordination Act.

c. Coordination with the Tennessee Wildlife Resources Agency.

d. Coordination with the State Historic Preservation Officer and President's Advisory Council on Historic Preservation.

9. Significant issues to be analyzed in the DEIS include impacts to fisheries, tailwater mussel resources, water quality, flood control, recreation, navigation, water supply, electric power production, economics, and community development. The U.S. Fish and Wildlife Service has agreed to be a Cooperating Agency on the DEIS. A DEIS should be available in June 2007.

10. Public Meetings: At present, no public meetings have been scheduled to scope for potential issues to be evaluated in the DEIS. Requests for public meetings should be directed to Mr. William Peoples, Chief, Public Affairs Office, U.S. Army Corps of Engineers, Nashville District, Nashville, TN, 37202-1070. Mr. Peoples may be reached by telephone at [phone].

Brenda S. Bowen,

Army Federal Register Liaison Officer.