Riesch, the overall cup points leader, came in ahead of Austrian Kathrin Zettel, who was second, and Finland's Tanja Poutiainen who came in third.
Lindsey Vonn of Vail, Colo., finished in a fourth-place tie with Anja Paerson of Sweden.
Riesch is 85 points ahead of Poutiainen in the overall points race.
2014: The Year in Fashion [PHOTOS]
UPI Sports Results for September 19, 2014