Preliminary results on phosphorus reduction in Lough Neagh - Assessing the effect against a background of change

Lough Neagh is a large (387 km²), shallow (mean depth 8.9 m) eutrophic lake. The phosphorus budget is described in order to illustrate that 75% of the particulate phosphorus input sediments to the bottom and that there is little retention of SRP in the lake. 54% of the SRP loading comes from sewage works and this is being reduced by phosphorus reduction at the major sewage works. There has been a downturn in the maximum algal crops, particularly of blue-green algae. However, there is an underlying upward trend in SRP loading and the paper stresses the importance of analysing trends in nutrient budgets to get an accurate evaluation of reduction strategies.