Nutrient losses from agriculture are one of the significant drivers for waters not meeting their environmental objectives under the Water Framework Directive (WFD). The most recent ecological status assessment (2016-21) indicates that just over 50% of our rivers and lakes and only 36% of our estuaries were in satisfactory ecological health, and overall water quality was in decline. EPA monitoring finds that nitrate concentrations remain too high in rivers, groundwater and estuaries in the south east and along the southern seaboard.
Nationally, there has been an increase in nitrate concentrations in groundwater, with little change in riverine nitrate concentrations, over the 12 months from 2022 to 2023.
- 43% of our rivers had nitrate concentrations higher than 8 mg/l NO3 in 2023, which may have a water quality impact on the ecological health in the downstream marine waters.
- 22% of groundwater monitoring sites had a mean nitrate concentration greater than 25 mg/l NO3, which is of concern because they are a significant deviation from natural conditions and are approaching the threshold where drinking water may be compromised.
- 6% of groundwater monitoring sites exceeded the groundwater threshold value of 37.5 mg/l NO3 in 2023.
Phosphorus concentrations are above the good status environmental quality standard in 22% of rivers, typically in areas associated with poorly draining soils. Elevated phosphorus concentrations are impacting the ecological health of these rivers and may be contributing to nutrient enrichment in the downstream estuaries.
Overall, to deliver improvements in ecological status and to achieve the WFD objectives, nutrient losses to water need to reduce. Mitigation measures need to be targeted to the critical source areas within sub-catchments. Measures to reduce phosphorus losses need to focus on breaking the pathway for run off over land and measures to reduce nitrogen losses need to focus on reducing the nitrogen surplus or load.
Report
This week also the Department of Agriculture released its new Nitrate Derogation Renewal Plan: Water and Agriculture, a collaborative approach that aims to address nutrient losses from agriculture.
