31-MW Prairie du Sac Facility Endures Test of Time

By Amanda Acton

Successful hydropower generation at Niagara Falls in 1896 was the catalyst for utilities and financiers across the U.S. and in Wisconsin to seriously consider the hydroelectric potential of rivers. In 1905, Magnus Swenson – a Norwegian immigrant, engineer, financier and inventor – decided to harness power from the Wisconsin River by forming the Southern Wisconsin Power Co. with two attorneys as partners.

After studying the river’s potential, Swenson’s company built Kilbourn Dam and powerhouse on the Wisconsin River in what is now downtown Wisconsin Dells (formerly known as Kilbourn). It began operations in August 1909. However, high construction costs and low power demand initially made the dam unprofitable. Undeterred, Swenson remained convinced he could yield economic gain by harnessing the river’s untapped power.

Swenson’s company acquired another site for a second dam, roughly one mile north of the Village of Prairie du Sac. Although the location presented construction challenges because of its sandy soil, he thought a hydroelectric facility at the site could potentially produce three times the amount of power as the Kilbourn project.

The Prairie du Sac hydroelectric facility was built about 30 miles northwest of Madison in south central Wisconsin. The project, completed in 1914, includes the Prairie du Sac Dam – which impounds the Wisconsin River creating Lake Wisconsin – and a powerhouse that provides a capacity of 31 MW.

Four-year fight

It took nearly four years and $1 million to construct the facility, including a one-year delay caused by challenges Mother Nature threw at the engineers and construction crews. Construction began in January 1911, but high water during the first year demolished the temporary train trestle used to transport construction materials to the Prairie du Sac site. Water also destroyed spillway foundation wood pilings and damaged part of the cofferdam protecting the powerhouse construction site.

Massive flooding occurred again in 1912, producing similar results. Problems continued in spring 1913, when ice jams became construction’s enemy and again wiped out the trestle and many pilings.

The Prairie du Sac facility was completed and commissioned in September 1914, despite having used somewhat primitive construction methods. When the facility began generating electricity, it was the largest hydroelectric power plant (in terms of capacity) west of Niagara Falls.

Techniques in the 1900s

Building the Prairie du Sac hydroelectric facility using today’s construction techniques and modern equipment would not have been difficult, but things were different in the early 1900s. The work was done with horses, shovels, picks, steam engines, deliveries by cart and extensive use of manual labor. Four hundred workers lived in temporary quarters and spent countless hours at the construction site. Many of the employees were Polish, Russian, Serbian and Italian immigrants recruited from Chicago. Employee family members often visited on weekends and shared the dining halls and other on-site structures.

This aerial view shows the 31-MW Prairie du Sac facility as it appears today.
This aerial view shows the 31-MW Prairie du Sac facility as it appears today.

Steam was the key power source used to build the dam. Not only did steam energize pile drivers, concrete mixers and cranes, it also allowed the railroad to extend the line at the site. Steam engine-powered trains delivered rock, materials and more than 12,000 wood pilings to secure the dam. These pilings were eventually driven into the Wisconsin River’s sandy bottom and covered with concrete placed around and over the pilings. Although the techniques used in constructing the facility are no longer employed, to this day, the pilings continue to hold the foundation on which the powerhouse and dam are built.

Beginning a utility

Once the Prairie du Sac hydroelectric facility began generating electricity, economics proved a tough nut to crack. Both the Prairie du Sac and Kilbourn hydro schemes were put into service without an existing need from local markets to purchase each facility’s power. Other than contracts with two utility companies located outside the area, demand for power remained minimal.

The numbers simply did not work, and Swenson’s dream was over. He was forced to sell both facilities in 1916 to the Milwaukee Electric Railway & Light Co. The new owners of the facilities developed a few local markets for power, but the properties changed hands again in 1917 and the Wisconsin Power, Light and Heat Co. was able to slowly begin posting a profit.

Horses pull cars on rails containing earthfill for the facility (circa 1913).
Horses pull cars on rails containing earthfill for the facility (circa 1913).

The new owners quickly began implementing plans to supply power for an interconnected utility system in central Wisconsin to serve undeveloped communities and those with small, obsolete power plants. The business extended transmission lines from the facilities to 13 community systems.

The availability of power from the Prairie du Sac and Kilbourn facilities ultimately spurred the construction of more transmission lines across the southern half of Wisconsin. Three more community systems came into the fold, and in April 1924, the utility’s name was changed to Wisconsin Power and Light Co. Wisconsin Power and Light Co., now Alliant Energy’s Wisconsin utility business, traces its birth to the hydroelectric generating facilities in Prairie du Sac and the Wisconsin Dells.

Tourism benefits from hydro

Boosting the local tourism industry was not a foundational reason to build the Prairie du Sac facility, but the benefit was immediate and it remains to this day. The dam created Lake Wisconsin, a 9,000-acre destination for boaters, anglers and nature lovers. During its active summer tourism season, tourists benefit from the local investment in lakeshore resorts, vacation homes and restaurants.

This bald eagle is one of many site visitors.
This bald eagle is one of many site visitors.

Constant water discharge from the Prairie du Sac generating facility makes the location directly downstream from the dam a year-round prime fishing spot because the waters do not freeze in winter. An added, unforeseen blessing from Mother Nature lies in bald eagles descending by the hundreds on the facility during their winter migration to feed on the river’s fish. Tourists come by the thousands, toting all kinds of photography equipment, to take advantage of one of the best spots in Wisconsin to view and memorialize our nation’s majestic national bird.

Marking 100 years of generation

The Prairie du Sac hydroelectric facility generates more than electricity; it also generates community pride.

On Sept. 12, 2014, Alliant Energy organized a celebration to commemorate Prairie du Sac’s 100th anniversary and recognize the rich history the dam and its economic impact have meant to the region. More than 120 federal and state agency representatives, state and local public officials, special guests and Alliant Energy employees attended the community celebration.

As successful as the event was, what was most impressive was the way in which the local community embraced the 100th anniversary. Local organizations planned events of their own and extended the celebration for weeks.

Four turbine-generators are pictured in the Prairie du Sac hydroelectric project as they appeared in 1914.
Four turbine-generators are pictured in the Prairie du Sac hydroelectric project as they appeared in 1914.

During the celebration, Alliant Energy, in partnership with the Sauk Prairie Area Historical Society, opened the Prairie du Sac facility for the first public tours in more than a decade. Eight Prairie du Sac Dam retirees and six current dam employees conducted tours for more than 900 people at the facility and the society’s dam exhibit. Ticket proceeds totaling more than $4,000 were donated to the society.

An evening themed “100 Years of Gratitude” took place on Sept. 13. The historical society, with additional funding provided by the county and private contributors, hosted the Prairie du Sac Hydroelectric Plant 100 Year deLight Party at their headquarters and the J.S. Tripp Heritage Museum.

Other community events commemorating the anniversary included a motorcycle ride and a bicycle ride featuring limited viewing of the dam’s powerhouse. The local high school football team used the facility as a backdrop for its annual poster featuring its players.

A man named Denman

Few people know more about the 100-year-old dam and its history than Denman Kramer. Kramer worked at the dam from 1947 to 1980 and served as the facility’s superintendent from 1959 to 1980. At age 97, Kramer continues to maintain his strong connection to and affinity for the dam. It’s kind of his hobby. He performed a reading of his poem, simply titled “The Dam,” at events dedicated to celebrating both the 75th and 100th anniversaries of the Prairie du Sac facility.

A 1936 graduate of Baraboo High School, Kramer began his career at the dam in 1940 as a shift worker, along with several workers who actually helped build it. His career took a six-year hiatus during service in the U.S. Army from 1941 to 1946. After finishing his service, he spent another year pursuing an education. Kramer returned to the dam as one of 40 employees, where he worked diligently and earned a promotion to superintendent.

Upon his leaving his position in 1980, Kramer was one of 25 remaining employees and, of those; he was the longest-serving.

A look ahead

The popularity of the Prairie du Sac hydroelectric facility has not waned, nor has Alliant Energy’s desire to continue its operation.

By popular demand, Alliant Energy offered public tours of the facility again in spring 2015. As with the 100th anniversary tours, hundreds of people turned out, and it was a challenge to secure available tour slots. When all was said and done, more than 1,700 people toured the Prairie du Sac facility in 2014 and 2015.

Members of the facility’s office force, construction crew and foreman are pictured on site during March 1914.
Members of the facility’s office force, construction crew and foreman are pictured on site during March 1914.

Alliant Energy has continued investing in the facility. Six of the eight generators have seen major overhauls over the years, and numerous safety improvements and refurbishments have been made. These ongoing investments are being done so the hydroelectric facility can operate safely for years to come. This generating station remains one of the most reliable and dependable facilities in the company’s fleet, and there appears to be no end to its success story.

It has been a privilege being involved in operating the project. Our team understands that running this nearly 102-year-old facility requires lots of ingenuity. Similar to Magnus Swenson, we are undeterred in our efforts to provide energy for the amazing communities that depend on the Prairie du Sac hydroelectric facility.

Amanda Acton is Alliant Energy’s manager for hydroelectric generation.

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