It is not only the characteristics of the pollutants that are important when considering the factors which influence water quality. The vulnerability – the natural characteristics of the water body where pollutants end up – has a significant influence on the impact of those pollutants. For instance, lakes are generally more vulnerable than rivers, because they accumulate pollutants. In the same way, some catchments are more vulnerable than others, depending on factors such as topography and soil type.
There are many ways in which nutrient losses can be mitigated, from planting riparian strips along stream banks to nutrient budgeting. Diffuse nitrogen is the greatest technical and economic challenge for nutrient mitigation. Constructing large wetlands in low-lying areas can remove significant amounts of nitrogen and phosphorus – but it is expensive. Keeping cows on stand-off pads or inside wintering barns can also be effective in reducing nitrogen leaching.