Wisconsin Historical Society

Historical Essay

From Water to Power - Image Gallery Essay

The Prairie du Sac Dam

From Water to Power: the Prairie du Sac Dam | Wisconsin Historical Society
Enlarge A man stands near the generators inside the power house.

Man Standing by Generators in Power House, 1915 ca.

A man stands near the generators inside the power house at the Prairie du Sac dam. View the original source document: WHI 48686

The Prairie du Sac Dam on the Wisconsin River has been powering communities in the area since 1914. The idea of constructing a hydroelectric power plant to harness the power of the river came from Norwegian immigrant, engineer and inventor Magnus Swenson. Although it took a little more than a decade for the dam to prove profitable, Swenson was ultimately proven correct and the surrounding areas of Sauk and Columbia counties have benefited from the dam's electric power production as well as the creation of Lake Wisconsin behind the dam. Images of the dam and power plant's construction, taken by local photographer Frank S. Eberhart, are the subject of this month's featured gallery from Wisconsin Historical Images, the Society's online image collection.

Hydropower Comes to Wisconsin

Magnus Swenson formed the Southern Wisconsin Power Company with attorneys E.J.B. Schubring and Phillip L. Spooner to study the hydroelectric potential of the Wisconsin River in 1905. The success of the power plant at Niagara Falls, opened in 1896, had made many investors and utilities across the country and across Wisconsin look seriously at rivers as potential sources for hydroelectric power. Based on the findings, Swenson's company built a dam and power plant at Kilbourn, now Wisconsin Dells, on the Wisconsin River in 1909. But the relatively low demand for electricity and the high cost of construction made the dam, at first, unprofitable.

Swenson, however, remained convinced of the river's economic potential and he acquired another dam site north of Prairie du Sac. While the site presented a construction challenge due to its sandy soil, a dam there could produce three times the power of the Kilbourn dam so plans called for the use of thousands of timber pilings to secure the plant to the riverbed.

Construction began in 1911. The railroad was extended to transport materials to the site, and a crews built a construction camp on the west bank of the river. Flooding in 1911 and 1912 and an ice breakup in 1913 damaged the construction site, but despite these setbacks the power plant began production in September 1914.

EnlargeLooking upstream (north) through the lock at the Prairie du Sac dam. The power house is on the left. The flow of the river has been diverted through the lock and the power house.

Lock at Power Dam, 1914

Looking upstream (north) through the lock at the Prairie du Sac dam. The power house is on the left. The flow of the river has been diverted through the lock and the power house. View the original source document: WHI 48492

The Dam Changes Hands

Demand for power remained minimal beyond existing contracts with Madison Gas and Electric and The Milwaukee Electric Railway and Light Co., though, and Swenson was forced to sell both the Kilbourn and Prairie du Sac dams in 1916. The dam changed hands again in 1917, but under new ownership and incorporated as the Wisconsin Power and Light Company, the business began profitably selling electricity over high-voltage transmission lines in south central Wisconsin.

The photographer, Frank S. Eberhart, operated a jewelry store and watch repair shop in town. After his glass-plate negatives turned up in the store, former power plant superintendent Denman Kramer donated them to the Society in 2007.

View the Gallery

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