The challenge for sustainable grassland production is to integrate economically profitable farming systems with environmental protection. The Water Framework Directive aims to attain at least “good status” for all waters by 2015, to be achieved through the introduction of measures across all sectors of society. Historically, the impact of grassland agriculture on water quality was investigated in isolation. More recently it has been highlighted that water quality and other environmental impacts such as greenhouse gas emissions must be considered in an integrated manner. Catchment hydrology is critical to understanding the drivers behind nutrient transport to surface water and groundwaters. Flashy catchments are more susceptible to phosphorus, sediment and ammonium loss, whereas contrastingly baseflow dominated catchments are more susceptible to nitrate transport. Understanding catchment hydrology enables the targeting of measures for the mitigation of diffuse agricultural contaminants. This increased understanding can also be used to support extended deadlines for the achievement of good status. This paper reviews the potential effects of grassland agriculture on water quantity and the transport of pesticides and nutrients to water in the context of achieving good status for all waters by 2015 under the Water Framework Directive. ; Peer-reviewed ; Department of Agriculture, Fisheries and Food; Environmental Protection Agency