The most common water quality problem arising from agriculture is excess nutrients, giving rise to eutrophication. Phosphorus is typically the issue for rivers and lakes, and too much nitrogen for estuaries and coastal waters. Excess ammonium may also be a problem in some waterbodies.
Nutrient losses from agriculture can arise from discrete or point sources such as farmyards, or from diffuse sources such as spreading of chemical fertilisers or organic manures.
Biological monitoring has identified excess fine sediment as an issue in some rivers. Fine sediment fills the spaces between larger gravels in the stream bed and can interfere with aquatic ecosystem functions, particularly in the more sensitive high status waters.
Typical sources of sediment from agricultural activities include: runoff from ploughed or arable land and farm roadways; erosion of river banks at cattle access points and; land drainage and channel maintenance. Mitigation options might include livestock exclusion, fencing the riverbank, attenuation ponds and careful management of ditches and drainage.
In order to maintain and safeguard our pristine waters within high status objective areas, it is vital to address the issues of nutrient loss and sedimentation. The Waters of LIFE IP will work with farmers to develop and trial appropriate mitigation measures to protect our rivers within high status catchments for the benefit of all.
For more information on the effects of agriculture on water quality, please go to catchments.ie