 The runners from the two turbines in the Cougar powerhouse experienced significant cavitation damage during operation and by the 1980s they were in need of repair and had to be taken out of service four times a year for inspections and repair.In 1987, the U.S. Army Corps of Engineers installed replacement runners that were designed by Voith Siemens Hydro Power Generation.By 2000, the replacement runners were again experiencing cavitation problems and in need of repair.