Agriculture’s use and impact on water resources involves complex trade-offs between economic, social and environmental demands under a wide range of institutional structures. Irrigated farming accounts for a major and growing share of farm production and rural employment in some OECD countries, but overuse of often scarce water resources is an increasing concern. Agriculture is a major source of water pollution but also contributes to ecosystem services (e.g. provision of habitat for some wildlife), for certain regions within some OECD countries. Agricultural production support and subsidies for variable inputs, especially for water and energy, continue to misalign farmer incentives and aggravate overuse and pollution of water across many OECD countries.