In 1991, the EU introduced the Nitrates Directive, which aimed to reduce water pollution caused or induced by nitrate from agricultural sources. The Directive requires Member States to apply agricultural action programme measures throughout their whole territory or within discrete nitrate vulnerable zones (NVZ’s). Action programme measures are required to promote best practice in the use and storage of fertiliser and manure by 4 key measures:

1. Limiting inorganic N fertiliser application to crop requirements.
   
2. Limiting organic manure applications.
   
3. Seasonal restrictions on the application of slurry, manure sand sludge on sandy and shallow soils.
   
4. Maintenance of farm records that encompass cropping, livestock numbers and fertiliser management.

Implementation of the directive across Europe has been generally poor. However, the synthesis of Member States' reports for 2000 concludes that 'Member States have in the last years shown a real willingness to improve implementation. They realise that costs induced by drinking water treatment for nitrates or by eutrophication in reservoirs and coastal waters are still increasing. Furthermore, the investments dedicated to urban wastewater treatment will be insufficient for nutrients without a parallel focus upon the agricultural sources of nitrate.

Nitrate pollution can be tackled at source. In Denmark, for instance, a national nitrate management plan began before the directive came into force. It offered advice to farmers on how to make efficient use of fertilisers and imposed annual nitrogen 'budgets' on farms. As a result, the leakage of nitrate from Danish farming systems has been substantially stemmed.

The patchy implementation of the Nitrates Directive has been reflected in a variable pattern of trends in nitrate pollution across Europe. Average nitrate concentrations in European rivers are falling. Denmark and Germany had the highest proportion of river stations reporting decreasing trends, indicating that national and EU measures introduced to reduce nitrate pollution are taking effect. The Czech Republic, Latvia, Hungary and Poland also had a high proportion of river stations reporting decreasing levels of nitrates.  These are likely to be related to the decrease in agricultural activities that has occurred in these countries since their transition to a market-oriented economy.