Dutch grassland farms that meet certain conditions may use more animal manure than the general limit of 170 kg nitrogen per hectare, as prescribed by the European Nitrates Directive. This partial exemption is referred to as 'derogation'. The National Institute for Public Health and the Environment (RIVM) and Wageningen Economic Research monitor the effects of this derogation on the water quality on 300 farms in the derogation monitoring network. This study shows the results for 2016 and the development from 2006 onwards. Management On average, derogation farms have used 238 kilograms of nitrogen from animal manure per hectare in 2016, the same amount as in 2015. The permissible amount of nitrogen from animal manure varies from 230 to 250 kilograms per hectare, depending on the soil and region. In recent years, improvements in management resulted in more efficient use of nitrogen for crop production; the nitrogen surplus on the soil surface balance has dropped with 16 %. And lower nitrogen surpluses lead to less nitrate leaching to groundwater. Groundwater quality From 2006, leaching of nitrate to the groundwater has stabilized or decreased on derogation farms. Since 2015, the average nitrate concentration in groundwater on derogation farms has been below the EU-standard of 50 milligram per liter, in all regions. Individuals farms however, may still exceed the standard. Even so, the amount of farms with nitrate concentrations below 50 mg/l still increases. In 2016, highest nitrate concentrations have been found in the Loess region (35 mg/l) and in Sand 230 (36 mg/l). In these regions there are soils for which nitrate is degraded in a lesser extent, and therefore can leach more to groundwater.