Cotherstone Water Waste Treatment Works dumped sewage into the River Balder 223 times in 2023 – an average of five spills per week – highlighting serious environmental concerns at the asite.
A recent Ofwat investigation resulted in Northumbrian Water agreeing to a £15.7m ‘enforcement package’.
The investigation followed an Environment Agency report last year which showed the extent of sewage spills into, amongst others, the River Tees and its tributaries.
There were also spills from sewage treatment and disposal works at Middleton, Romaldkirk, Barnard Castle, Whorlton, Boldron and Gainford, as well as pumping stations at Startforth and Langton.
There were additional spills into the River Gaunless near Evenwood and Copley.
In its report about the investigation, Ofwat said: “We have identified that a high proportion of Northumbrian Water’s WWTW storm overflows spill regularly into the environment.
“For example, 75 per cent of its WWTW storm overflows spilled 20 or more times in 2021; and 47 per cent spilled more than 60 times in that year. Likewise in 2022, 24 per cent of its WWTW storms overflows spilled 60 or more times and 72 per cent spilled 20 or more times.
In 2023, this was 44 per cent spilling more than 60 times and 83 per cent spilling 20 or more times.
“In a number of cases, Northumbrian Water has failed to demonstrate that these spills resulted from exceptional circumstances or that it would have been excessively costly to address spills from these storm overflows.”
Lynn Parker, senior director for enforcement at Ofwat, said: “Our investigation has found failures in how Northumbrian Water has operated and maintained some of its sewage works and networks, which has resulted in excessive spills from storm overflows.
“The contraventions we have found at some of their sites will have had an impact on the local environment and customers and it is unacceptable.”
Ofwat said the “enforcement package” Northumbrian Water agreed to is greater than any penalty that would have been imposed and the cash would be put back into improving the water sector.
Had a penalty been imposed the money would have gone into a consolidated fund operated by HM Treasury
The company said, among others, £2m will be put into a “branch out” fund which will award grants of up to £10,000 for local projects to improve the environment and £2m will be invested into reducing spills at specific overflows.
