Will recent improvements in estuarine water quality in Ireland be compromised by plans for increased agricultural production? A case study of the Blackwater estuary in southern Ireland

Abstract

The environmental status of many European estuaries has improved in recent years as a result of the implementation of a range of different legislative measures. Better municipal waste water treatment and a reduction in the application of inorganic and organic fertiliser to agricultural lands are the main reasons for these improvements. It is anticipated, however, that the ending of the EU milk quota in 2015, and the proposed enlargement of the European dairy sector will lead to a market-driven increase in milk production through an increase in animal numbers and higher productivity. This new production is likely to lead to an increase in pressures with the potential to impact on the quality of surface waters, including estuarine waters. In this paper we focus on the Blackwater estuary in southern Ireland which has seen a marked improvement in water quality due to a reduction in riverine nutrient inputs of phosphorus and nitrogen. A bio-physical model is used to test nutrient-input scenarios likely to represent the range of nutrient loadings that may arise as a result of increased agricultural production. The outputs from these different scenarios are used to assess if recent improvements in estuarine water quality will be undermined or even negated by the proposed expansion of the Irish dairy sector. Appropriate management options to address these potential impacts are discussed.