Given seasonal and inter-annual variability of demand and supply, and the wish to maintain an environmental flow level, high ratios imply a high risk that water supply will be inadequate. Agriculture was the largest user of water, accounting for about 70% of total global freshwater demand (OECD, 2008c). The largest global water demand after irrigated agriculture in 2000 was for electricity generation, primarily for cooling of thermal (steam cycle-based) power generation. This is despite increases in abstractions for public water supply and, to a lesser extent, irrigation.