MADISON, Wis. (AP) -- Construction work on a high-voltage transmission linking Iowa and Wisconsin has been completed and the line is fully operational, a group of utilities announced Friday.

American Transmission Company, Dairyland Power Cooperative and ITC Midwest began work on the 102-mile (164-kilometer) Cardinal-Hickory Creek line between Iowa's Dubuque County and Wisconsin's Dane County in April 2021. Construction wrapped up late last week, ITC Midwest spokesperson Rod Pritchard said. The 345-kilovolt line was fully energized Thursday.

The utilities say the line will improve electrical reliability and support renewable energy projects.

A coalition of conservation groups filed a federal lawsuit in March seeking to block the final mile (1.6 kilometers) of construction across the Upper Mississippi River National Wildlife Refuge near Cassville, Wisconsin. They argued that the line would damage the refuge and that the utilities improperly acquired the land from the U.S. Fish and Wildlife Service. A federal appellate court in May allowed the work to continue.

The utilities said in a news release Friday that they tried to protect the refuge during construction, using wooden mats to reduce soil disturbance, and that no grading took place.