Hegg Memorial Health Center (Rock Valley, Iowa). Hegg Memorial Health Center is a 25-bed critical access hospital. The hospital is located in far Northwest Iowa between two larger cities; Sioux City, Iowa, and Sioux Falls, S.D. and is part of Sioux Falls-based Avera. Hegg Memorial was named a 2015 Top 100 Critical Access Hospital by iVantage Health Analytics. The hospital has been named one of the top critical access hospitals in the country by iVantage Health Analytics for the past four years.