Northern Ireland’s Victorian sewage systems are still dealing with sewage and rainwater in the same pipes – and that can be a big issue when there’s heavy rain.
When this happens, or the system is at risk of being overwhelmed, a network of combined storm overflows, or CSOs, discharge surplus wastewater into rivers, lakes and the sea.
Muir said these discharges had contributed to a fall in water quality, a build-up of nutrients and the algal crisis in Lough Neagh and a decline in the quality and market value of commercial shellfish nurseries in Belfast Lough.
Statistics from NI Water, external show CSOs discharged more than 24,500 times in a year.
The minister added that a review of environmental governance had found that it was “clear” the SoRPI arrangements between NIEA and NI Water were “not working as they were designed to”, as NI Water had prioritised drinking water over wastewater due to a stricter regulatory regime.
The review also called for an independent environment agency for Northern Ireland.
But Muir said that had stalled in the executive and the required legislation would not now be passed by the end of the mandate.