Background Information About the Toledo Bend Project

Background

The existing facilities at the Toledo Bend Project include a dam and powerhouse, spillway, tailrace and canal, transformer and switchyard, turbines, penstocks, and transmission lines. The SRAs began land acquisition in May 1963, and initiated construction of the dam, spillway and powerhouse in April 1964. The closure section of the earthen embankment and impounding of water was completed in October 1966. The powerhouse was completed and began operating in the early part of 1969.

The Spillway

Power HouseThe spillway is located along the north dam abutment in Louisiana. The overall length of the spillway structure is 838.0 feet and the flow of water over the concrete gravity-type gated weir is controlled by eleven 40-by-28 foot tainter gates. The gated weir also includes a concrete chute and stilling basin with a discharge channel on the left abutment. The elevation of the top of the gates is 173 feet msl. Also contained in the spillway structure is an 8.33-by-12 foot low flow sluiceway. The low flow sluiceway is at an elevation of 100 feet msl.  

Since December 2000, improvements to the spillway operation notification procedures, including the installation of a NOAA radio transmitter, public notices of anticipated spillway operations, real-time information available through several media sources, and the improved coordination and cooperation between the Authorities and State and local government emergency management agencies have been positive steps in providing timely notification of spillway operations during large flow events.

The Reservoir

With a drainage area of 7,190 square miles, the Toledo Bend Reservoir is the largest man-made body of water in the South. The reservoir is approximately 85 miles long (navigation miles) with approximately 1,200 miles of shoreline at the reservoir’s normal elevation (172 feet mean sea level msl). Toledo Bend Reservoir is located in a relatively flat region and most of its shoreline is gently sloping. The Project encompasses an area of 197,660 acres, with the reservoir covering approximately 185,000 acres. The full pool (185,000 surface acres) has a controlled storage capacity of 4,477,000 acre-feet or 1,448,934,927,000 gallons at 172 ft msl. The maximum drawdown surface area of the reservoir is 136,560 surface acres at an elevation of 162.2 feet with a capacity of 2,922,800 acres-feet. The operation of the reservoir for water supply could result in reservoir elevations lower than 161.52 ft msl. The average depth of the reservoir is 24 feet with the deepest point at 100 feet near the dam. The upper reaches of the reservoir and its numerous coves are relatively shallow.