January 20th 2001

Water Pollution

High nitrate levels in drinking water are a public health issue and as such are more serious than many other pollution problems. The most recent health problem to be linked to high nitrates in drinking water is non-hodgkins lymphoma (cancer of the lymph system).

The EU Nitrates Directive (1991) declared 50 mg/l as the upper limit for nitrate in drinking water. This directive also obliged national governments to declare Nitrate Vulnerable Zones (NVZs) in sensitive areas. EPA reports on nitrate levels indicate a significant number of public supply sources in eastern, south-eastern and southern counties have mean nitrate levels greater than the EU guide level (25 mg/I). Even more serious are indications that levels are continuing to rise.

Twelve groundwaters have been identified as being polluted or susceptible to pollution by nitrates in 5 counties - 3 in Carlow, 4 in Cork, 1 in Kerry, 2 in Louth and 2 in Waterford. The extents of the catchments which contribute to these waters are now being identified and formal designation of these areas as NVZs is expected later this year. Action programmes for the NVZs involving public consultation are expected to be developed by the end of 2001. The designation of another dozen NVZs is expected at a later stage.

NVZ designation may impose severe restrictions on farming practices including stocking rates. In keeping with the 'polluter pays principal' there is no provision for compensation. The voluntary Nitrate Code of Practice published by Government in July 1996 will become mandatory in all designated zones. The good news for REPS farmers is they are already complying with the likely requirements.

Nitrate is one of the common contaminants identified in groundwater worldwide. It is highly mobile and easily leached from the plant rooting zone. Up to now nitrates in groundwater have posed fewer problems in Ireland than in most other countries with intensive agriculture. However, the use of fertiliser nitrogen has increased by more than 60% in the period 1980-1999. Recently, usage has declined on REPS and other extensive farms while it has increased (17% since 1994) on intensive farms.

In the past, high nitrate levels have tended to be associated with intensive tillage. Some of the highest levels now being recorded relate to intensive dairying and possibly pigs. The main practices which contribute to nitrate leaching in vulnerable (shallow, light and free draining) areas, and which should be avoided, include:

Nitrogen application in excess of crop requirements.

Slurry application during the months of October, November and December.

Late application of Nitrogen - after mid September.

Farmyard seepage particularly the practice of diverting effluents to soakaways.