AQW 26595/17-22

Miss Rachel Woods
Green Party
North Down

Tabled Date: 29/11/2021
Answered On Date: 03/12/2021
Priority Written: Yes

Question:
To ask the Minister for Infrastructure, pursuant to AQW 25418/17-22, (i) whether the annual spill referred to in her Department's letter deposited in the Assembly Library relates to untreated sewage discharged into Northern Ireland's rivers and seas; and (ii) which year these figures relate to.

Answer:

NI Water has advised that:

The spill information provided in the response to AQW 25418/17-22, refers to predicted spills as generated by the Drainage Area Plan (DAP) models. As referenced in my previous answer, combined sewer overflows and emergency overflows operate during periods of heavy rainfall, or in the event of an operational breakdown. This results in discharge into the receiving watercourses, or the marine environment and ultimately the sea. Although it is untreated sewage that is discharged during these times, there will be a high level of dilution due to the presence of storm water, and the swell of the receiving watercourse due to the rainfall event.

The table of spill frequencies are effectively an annual average, based on 20 years of historical recorded rainfall data and, therefore, do not relate to a specific year.