New powerhouse proposed for Twin Falls hydroelectric plant

Current powerhouse photo taken from proposed site.

We're planning to build a new powerhouse at the aging Twin Falls hydro plant that borders Wisconsin and the Upper Peninsula of Michigan on the Menominee River.

Built in 1912, the dam is licensed to operate to 2040. The powerhouse was built at the same time, but its condition is such that it won't be able to operate for the license duration. Various repairs and upgrades to the dam and spillway structures have been completed since the mid-1960s, and the time has come for the powerhouse to be addressed.

We are proposing a new powerhouse on the Wisconsin side of the Menominee River to replace the current one on the Michigan side. The project also would include adding spillway capacity to meet current Federal Energy Regulatory Commission (FERC) safety standards.

Building on the opposite side of the river would allow the existing plant to continue generating electricity during the two years the new powerhouse would be built.

Maintaining the current powerhouse during construction also would allow water passage during winter. Although spillway gates can freeze in the last position set during the winter, water passing through the powerhouse turbines in winter would be adjusted to comply with FERC license requirements. If the existing powerhouse were to be removed to make way for new construction, we would be unable to manage the river through the powerhouse during the two winter seasons of construction.

New powerhouse construction requires multiple approvals, including:

• License amendment issued by FERC. 
• Certificate of Authority from the Public Service Commission of Wisconsin. 
• Permits from Wisconsin Department of Natural Resources, Michigan Department of Environmental Quality and U.S. Army Corps of Engineers. 
• Consultation with state historic preservation groups and Native American tribes. 

After working through the required amendments and permits, construction is targeted to begin in the spring of 2014 with an in-service date of summer 2016 for the new powerhouse. The old powerhouse would be taken down in the summer of 2017.