Unique hydro project powered the Ozarks for 93 years
For 93 years, a unique hydropower project known as Tunnel Dam has helped power the Ozarks. Its source of energy comes from water backed up by a dam on the Niangua River. Tiny by comparison to the other sources of power for electric co-op members in Missouri, the project’s days are numbered. But the engineering that went into its construction and its remarkable history will long be a source of pride for those who have kept it operating over the years.
Sho-Me Power Electric Cooperative, which provides electricity to nine electric cooperatives and Fort Leonard Wood, plans to shut down the plant when its license to operate it expires in June 2024. But it plans to keep the dam in place, allowing outdoors enthusiasts to continue enjoying the beautiful spot well into the future.
Engineers looking for the next source of electricity in the early 1900s had long cast their eyes on the Niangua River. Since the 1850s, the Niangua had powered 33 gristmills thanks to the output of many large springs. These include Bennett Spring, which averages 100 million gallons daily.
Specifically, they saw potential in the long, lazy Whitworth Bend in the river east of Camdenton where the Niangua flows for 6 1/2 miles and ends up just a quarter mile away on the other side of a steep ridge. The idea was to dam the river, enlarge a cave that passed through the ridge and put a powerhouse on the other side that would be powered by water pouring downhill through the cavern.
The first attempt to tame the river, however, was seriously underfunded and unrealistic in its estimates. It ended after enlarging the cave only a short distance when workers discovered the cavern’s many branches would have siphoned off too much of the water.
In 1922 another attempt was launched, this time with serious cash behind it. Enter the Quigley family, who in 1920 organized the Missouri Water Power Co. and Quigley Construction Co. in order to build a series of hydropower projects on the Niangua.
Its investors boldly predicted the new lake would be 25 miles long and the turbines would produce enough electricity in one day to power the city of Lebanon for an entire month. They promised that this would be the first of four dams on the Niangua.
The July 24, 1922, Springfield Leader inaccurately reported that the tunnel was nearing completion and work on the dam would start soon. The story reported a contract had been signed to provide power to Lebanon, in addition to 20 other towns that had signed on. It hinted the plant might even supply electricity to Jefferson City.
However, by the end of 1923, no real work had been completed. No power had been delivered to Lebanon, so the city cancelled its contract. The Missouri Water Power Co. sold its interests in the unfinished project to the Central States Power and Light Corp., parent company for the Missouri Electric Power Co. They would employ the Management and Engineering Corp. to complete the job.
A huge force of men and machines were hauled to the site. An entire village, dubbed White City, was built on the rocky ridge to house the workers. Tons of rock to form the dam were blasted from hillside quarries. A concrete plant was constructed. A cable car was built to move men and the generators down the steep slope to the powerhouse. On the other side, a chute delivered concrete for the dam.
The cave idea was abandoned. Instead, hard rock miners were brought in to blast a 13-foot-tall tunnel 830 feet long through the ridge. At the same time workers built a dam 24 feet in height and 300 feet long. The dam formed Lake Niangua, which extends 2 1/4 miles up the river and covers about 360 acres at normal pool.
In two years of backbreaking labor, the Niangua Hydroelectric Project, better known locally as Tunnel Dam, began generating electricity for the Missouri Electric Power Co., which served around 40 small towns in Missouri. It became property of Sho-Me Power Electric Cooperative when the transmission co-op bought most of the assets of the power company in December 1943.
In operation, water from the lake drops 40 feet while passing through the tunnel and into the powerhouse on the other side of the ridge. Here it drives two 7-foot water wheels, which in turn power two Allis-Chalmers vertical generators rated at 1.875 megawatts each.
Originally the plant had three employees who operated it. The radio used to communicate with Sho-Me’s offices became a lifeline for local residents in the days before phone service. In the late 1960s, Sho-Me Power converted the plant to remote operation.
Today, 93 years later, Tunnel Dam continues to generate electricity for electric co-op members. But that will end soon. In June 2023, Sho-Me began the process of shutting down the plant.
“Sho-Me has determined that it is no longer economically viable to operate the project for a new license term, which would last 30 to 40 years,” says John Richards, CEO of Sho-Me Power. “Therefore, Sho-Me no longer intends to seek a new license for the project. As such, Sho-Me is in the process of surrendering the license and ceasing generation of power, while keeping the dam, Lake Niangua and associated project facilities in place and open to the public for enjoyment.”
He adds that the dam is safe and in good condition. Sho-Me will continue to own, monitor and maintain the dam to the same level it has historically.
It’s not that the project no longer functions, or that the power it generates is no longer needed by electric co-op members. The issue is the small amount of water available for generation. The dam typically provides less than one-tenth of 1% of Sho-Me’s energy requirements. The rest comes from Associated Electric Cooperative in Springfield.
News that the dam and lake would remain were well received by anglers attending public meetings held by Sho-Me. The dam site is a popular recreation area for those willing to make the drive down rugged gravel roads.
Sho-Me Power’s good-neighbor policy provides access not only to the lake but also to the river below the dam and at the powerhouse. That will continue, as long as water flows downstream.
Watch the video below to see how Tunnel Dam operates.