Wilson Dam & Hydroelectric Plant, Stoney Spillway Gate, Spanning Tennessee River at Wilson Dam Road (Route 133), Muscle Shoals, Colbert County, AL

Significance: The purpose of spillways and spillway gates is to control the excess flow of water not used by the turbines or stored in the reservoir. Such headwater control is accomplished at Wilson Dam by the use of 58 bintage gates called Stoney gates. The Stoney gate is known generically as a crest gate. Crest gates are a type of spillway control in which the damming surface, in this case the gate itself, is raised to allow the water to discharge between its lower edge and the fixed crest of the dam spillway. The Stoney gate is unique for the way in which it lifts and closes between the spillway piers of the dam. The gate bears upon one set of rollers that are located between two sets of fixed tracks, one set of tracks mounted on the gate, the other set mounted on the piers of the dam. The rollers are not affixed to either set of tracks, which allows the rollers and gate to move independently. When the gate lifts, the rollers move upwards only half as far as the gate, keeping only the bearing section of the gate in contact with the rollers during operation. At Wilson Dam, the motive power for raising and lowering each spillway gate was supplied by a double system of counterweights. The first system consisted of a fixed or "dead" counterweight that supported half the weight of the gate. The second system, the one that actually started gate opening, was hydraulically operated by means of two large counterweights, each suspended in its own displacement well located on either side of the gate. In the closed position, a head of water inside each well would support the counterweight. In opening the gate, the water inside the well would be discharged into the tail water, allowing the counterweight to descend and operate a series of chains and pulleys which would, in turn, raise the gate. With this system of gate control, all of the 58 Stoney gates could be opened and closed in less than two hours. Over the years, this double counterweight system was replaced by electric winches. The Stoney gates, however, still remain, and continue to fulfill a crucial role at Wilson Dam.
Unprocessed Field note material exists for this structure: N168
Survey number: HAER AL-47-D
National Register of Historic Places NRIS Number: 66000147