Sioux Valley Energy’s History Goes Back to 1938. Three Electric Cooperative Groups Were Organized That Year; The First Was the Sioux Valley Electric Association of Brookings and the Other Two Organizations Were East Central South Dakota Electric Association and the Sioux Empire Electric Association. All Three Had Taken Preliminary Steps Towards Seeking a Loan from the Rural Electric Administration (Rea). The Three Organizations Held a Joint Meeting in December of 1939 and Voted to Merge Together. The New Cooperative Was Named Sioux Valley Empire Electric Association, Inc.