Floating desalination. Desalination barges have operated since 2008 to meet high seasonal demand for potable water along the Red Sea coast of the Kingdom. In 2010 the largest floating desalination plant in the world, with a production capacity of 25,000 m3/day (9 million m3/year), was launched on a barge in Yanbu. It is sufficient to supply a city with more than 100,000 inhabitants with drinking water. The country's mean annual surface runoff has been estimated at more than 2 billion cubic meters per year. The country has eleven renewable alluvial aquifers with an estimated combined mean annual recharge of nearly 1 billion cubic meters per year. According to the World Resources Institute the renewable groundwater and surface water resources overlap, i.e. the entire renewable groundwater resources originate in recharge from rivers (Wadis) so that total renewable water resources are in the order of 2 cubic kilometres/year. Surface resources and renewable aquifers are concentrated in the west and southwest, where rainfall is higher. The Saudi water sector, like the entire country, has undergone tremendous changes over the past decades from a system based on the use of local renewable water resources for small-scale irrigation and limited domestic uses to a system largely based on the use of desalinated water and fossil groundwater for large-scale irrigation and domestic, commercial and industrial uses at a level comparable to developed countries. The Saline Water Conversion Corporation, created in 1965, has been an important player in this process of change. Until 1994 domestic water use was entirely free in Saudi Arabia. Only then a very moderate tariff has been introduced. In the early 2000s the government decided to involve the private sector not only in the construction of infrastructure, but to expand its role also to the financing and operation of infrastructure through Build-Operate-Transfer (BOT) projects. The first BOT project in the water sector was a wastewater treatment plant in Jeddah, followed by Independent Water and Power Projects (IWPPs) for integrated power and desalination plants. In 2003 the Ministry of Water and Energy was created. It took over the water resources management function from the Ministry of Agricultural and Water and the responsibility for water supply and sanitation from the Ministry of Municipal and Rural Affairs. In the same year the Water & Electricity Company was created as an off-taker for water and electricity produced by the IWPPs. In 2008 the privatization program was expanded to drinking water supply when the Kingdom's first management contract was signed for the capital Riyadh, followed by two more management contracts (see below).