 RAPID CITY, S.D., June 01, 2021 GLOBE NEWSWIRE -- Black Hills Corp. NYSE: BKH today announced that its natural gas utility subsidiaries in Colorado and Iowa separately filed rate review applications to recover investments made in natural gas infrastructure systems in their respective states. These critical investments were required to meet system growth, ensure the safe and reliable delivery of natural gas to customers homes and businesses, and meet compliance requirements of state and federal regulations. 