West of Castlereagh Rd are the Penrith Lakes, a series of flooded quarries. The quarries were formed by a quarrying conglomerate in 1979. The site supplies around 75% of Sydney's sand and crushed aggregate requirements, including about 85% of the materials for ready mixed concrete. One of these lakes is the Sydney International Regatta Centre which hosted the rowing events of the Sydney 2000 Olympics. There is also the popular Penrith Whitewater Stadium which hosted whitewater slalom events for the Sydney 2000 Olympics. The Penrith Lakes Development Corporation (PLDC) oversees implementation of the Penrith Lakes Scheme.