Perth's water supply has traditionally relied on both groundwater and rain-fed dams. Reduced rainfall in the region over recent decades had greatly lowered inflow to reservoirs and affected groundwater levels. Coupled with the city's relatively high growth rate, this led to concerns that Perth could run out of water in the near future. The Western Australian Government responded by building desalination plants, and introducing mandatory household sprinkler restrictions. The Kwinana Desalination Plant was opened in 2006, and Southern Seawater Desalination Plant at Binningup (on the coast between Mandurah and Bunbury) began operating in 2011. A trial winter (1 June – 31 August) sprinkler ban was introduced in 2009 by the State Government, a move which the Government later announced would be made permanent.