The cooperative will build over 100 wind turbines for the PrairieWinds wind farm in central South Dakota.
The $204 million loan guarantee will be funded by the US Department of Agriculture's Rural Utilities Service and covers 60 percent of the total $340 million cost.
PrairieWinds is next to a smaller 10.5MW wind project owned by South Dakota Wind Partners, a group of local community investors.
The Western Area Power Administration approved the connection of both wind farms to the grid in October.