It is expected that significant issues with algal bloom in Lough Neagh will return again this year, so we can expect further scrutiny on the source of excess phosphorus (P) getting into the Lough?

At a joint meeting of the Stormont Agriculture and Infrastructure committees last Tuesday, officials from NI Water set out the extent to which its wastewater treatment plants are adding to the problem.

Their best estimate is that within the Lough Neagh catchment, 545t of P enters the sewer network annually, with 88% removed during treatment, leaving 65t of P being returned in discharges to water bodies.

Adding in a small percentage of P lost from the network each year, the total figure comes to approximately 70t. This equates to around 20% of the annual total P in rivers flowing into Lough Neagh.

Overflows

Officials also acknowledged that storm overflows happen during high rainfall events to help prevent flooding, but maintained that they actually account for less than 1% of P losses.

NI Water does not routinely discharge untreated raw sewage into Lough Neagh, although raw sewage does go into Belfast Lough – major capital investment is required to tackle that urban-based issue.

As well as agriculture, other sources of P getting into Lough Neagh include from industry and septic tanks.

Solutions

Unlike these other sources, agriculture has come forward with solutions, whether via the Soil Nutrient Health Scheme (SNHS) or the Sustainable Use of Livestock Slurry (SULS) project. In simple terms SULS involves taking slurry solids to anaerobic digestion plants, where it is used to create green energy such as biomethane, which can be injected into the gas grid. The resultant digestate is dried down to produce a high-P biofertiliser that is potentially exported out of NI.

The principle is sound, but one of the major blockages will be getting planning in place for all the necessary infrastructure.

There are a number of recent examples which suggest this can be a fraught process, especially if some locals object. High level political leadership is required.