Calderwood Hydroelectric Development

The Calderwood Hydroelectric Development meets National Register criteria A and C for its historical, architectural, and engineering significance. Under National Register criterion A, the Calderwood facility is significant in the industrial development of Tennessee. By the mid-20th century, Alcoa emerged as one of the leading manufacturers in the state, and the development of the Alcoa facility in Blount and Monroe counties made this region an industrial center. Alcoa employed thousands of workers in its aluminum plants, and its hydroelectric facilities made this production possible. Under criterion A, the Calderwood Hydroelectric Development is also significant for its role in military history. During World War II, the increased reliance on air power to fight the axis powers required enormous amounts of aluminum for aircraft production and other war materials. The power supplied by Calderwood was integral with this significant role played by Alcoa.

The Calderwood Hydroelectric Development is also significant under criterion C for its engineering and architectural design. The Calderwood Powerhouse is a notable example of a Colonial Revival style industrial building. The Calderwood Dam is notable for its engineering significance. Its unique design is well suited to its site, which has steep rock walls that make side spillways impractical. Flood waters spill freely over the crest without contact with the dam. The design also includes a 40-foot high auxiliary dam approximately 300 feet below the main structure. Inspired by natural waterfalls, this arrangement creates a deep pool to still the water and absorb its energy without damaging the dam or the river bed. Water strikes a U-shaped deflector at the bottom of the pool, which doubles its effective depth.

The primary buildings and structures that comprise the Calderwood Hydroelectric Development are also notable for the retention of their historic and architectural character. The dam possesses its original poured concrete exterior surface, along with ancillary structures such as gatehouses and gantry cranes. The powerhouse retains original windows, decorative detailing, and interior floor plan and layout, and its character remains intact.

In addition to the primary buildings and structures, the Calderwood Hydroelectric Development maintains its sense of time and place as a planned early- to mid-century hydroelectric development. The mountainous landscape looks much as it did when the facility was completed, and there is no substantial residential or commercial development in the vicinity of the dam and powerhouse, or along the reservoir shoreline. The intact hydroelectric facility retains its historical integrity and reflects the industrial growth of a major American industry. The Calderwood Hydroelectric Development meets the registration requirements set forth in the Multiple Property Documentation Form, "Historic Resources of the Tapoco Hydroelectric Project."