Arkansas-Missouri Power Company
This building was constructed by the Arkansas-Missouri Power Company in 1927. The generator and equipment inside are all original, with the exception of the oil circuit breaker which was replaced in 1956. At a cost of $11,000, the generator was rated at 550 Kilowatts and could produce 2400 volts at a speed of 150 RPMs.
This plant was taken out of service in 1972 because it was no longer economical to operate due to high operating and maintenance costs. Arkansas-Missouri Power Company donated this hydroelectric plant to Arkansas State Parks in 1972.
• The exciter provides direct current to the generator.
• The generator, connected to the turbine, rotates as the turbine spins. This produces electricity.
• As water enters the turbine well, the turbine is turned by the force of water hitting the blades.
• Water exits the hydroelectric plant and flows downstream.
Topics. This historical marker is listed in these topic lists: Industry & Commerce • Waterways & Vessels. A significant historical year for this entry is 1927.
Location. 36° 29.697′ N, 91° 32.076′ W. Marker is in Mammoth
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Other nearby markers. At least 8 other markers are within walking distance of this marker. Dam Site #1 and Mammoth Spring Milling Company (within shouting distance of this marker); The Development of Mammoth Spring (about 300 feet away, measured in a direct line); What Am I Standing On? (about 300 feet away); Mammoth Spring (about 400 feet away); The Inspiration for The Grand Ole Opry (about 500 feet away); Mammoth Spring Depot (about 600 feet away); a different marker also named Mammoth Spring Depot (about 600 feet away); The Big Gun (about 600 feet away). Touch for a list and map of all markers in Mammoth Spring.
Related markers. Click here for a list of markers that are related to this marker. Mammoth Spring State Park
—Dr. David Dale Owen
1st State Geologist for Ark
1857
Prior to the construction of this hydroelectric plant in 1927, this site provided mechanical power from falling and flowing water. The water power was used for milling, grinding and manufacturing operations.
In 1917, a travel brochure funded by the Frisco Railroad, stated that Mammoth Spring was the leading town between Memphis, Tennessee and Springfield, Missouri. It was the natural resource of water and the ingenuity of man that made Mammoth Spring a thriving center of commerce.
Although previous dams had been built at this site, the present dam was built in the 1880s. The spillway section is 110 feet long, with a 7 foot wide spillway and a 10 foot wide base. It is constructed of limestone blocks and earth fill set in a concrete footing in solid rock. The spill was a free "over fall" type that allowed the water level to drop freely. The dam served the Mammoth Spring Milling Company by powering roller mills used to grind soft wheat.
In 1925, Arkansas-Missouri Power Company, a subsidiary of Inland Power and Light Corporation, purchased the dam; they constructed this hydroelectric plant in 1928. The plant was operated by the Arkansas-Missouri Power Company until 1972 when it was donated to Arkansas State Parks.
The equipment you see is original, installed in 1928, with the exception of the oil circuit breaker which was replaced in 1956.
In 1981, a feasibility study was performed under a contract between the Arkansas Department of Energy and Benham-Blair and Affiliates, Inc. The Ozarks Regional Commission provided the funding to assess the feasibility of restoring or replacing the plant. It was determined that operation of the plant would be uneconomical.
The turbine spins much like a pinwheel as you blow air into its folds. Rather than air, the directed force of over 9 million gallons of water per hour turned the turbine. As the turbine rotated, the shaft connected to it turned the electromagnets in the generator and created electrical energy.
Turbine
Manufacture: The James Leffel & Company
Order No: W1340
Type: B
Mfg. Date: 1926
Speed: 150 RPM
This governor was designed and built by the Woodward Governor Company in Rockford, Illinois. The shop order, dated September 1, 1927, shows that the governor was inspected by Elmer E. Woodward, son of the founder of the Company, who developed this model of governor controls.
The governor opened and closed the gates that allowed water to flow through the turbine. Because this governor used an open oil system, it required the oil reservoir to the right.
Governor
Manufacture: Woodward
Number: 5985
Type: HR 8400 FT-LBS
Size: 775 x 12
As water enters the turbine well the turbine is turned by the force of water striking the blades.
This exciter provides direct current to the generator.
This generator is connected to the turbine and produces electricity as the turbine spins.
Credits. This page was last revised on February 17, 2022. It was originally submitted on February 15, 2022, by Cosmos Mariner of Cape Canaveral, Florida. This page has been viewed 399 times since then and 101 times this year. Photos: 1, 2, 3, 4, 5, 6. submitted on February 16, 2022, by Cosmos Mariner of Cape Canaveral, Florida.
