The firm released untreated sewage from storm overflows 70,062 times, the second worst performance of 10 water firms in England and Wales, behind United Utilities. It also discharged sewage from overflows for a total of 406,131 hours, second worst behind Severn Trent.
However the company does have the highest number of monitored overflows at 2,178.
The overflows are designed as a safety valve to ensure sewage does not back up into people’s homes when the system becomes inundated with heavy rainfall. But critics say the system has become so inadequate that it can be triggered with “pitiful” amounts of rainfall “sometimes as little as 2mm” and there’s been a growing public backlash over the practice.
Environment Agency chief executive Sir James Bevan claimed the agency was holding water firms to account “on a scale never done before” and companies “need to act now to reduce their overflows to the minimum possible”.
The data was published at the same time as the government announced what it said was the largest overhaul of the sewer system since the 1990s.
It launched a consultation over setting a series of targets for water companies with the ultimate aim of stopping 80 per cent, or 320,000 discharges into waterways from storm overflows, by 2050.
The Angling Trust welcomed the move but said more urgency was needed. Head of campaigns Stuart Singleton-White said only 14 per cent of rivers meet “good ecological status”, as judged by the Water Framework Directive, but not a single one meets good chemical status.
He said: “The government has all the tools it needs; new laws in the Environment Act, new duties on Ofwat, and the overwhelming support of the public who want to see clean rivers and seas. I very much hope the government will now drive this forward with a lot more urgency.
“Let’s not wait to 2050 before we get the job done.”
Under the proposals by 2035 there will be 70 per cent fewer discharges into bathing waters, and by 2040, around 160,000 discharges will have stopped.
YW said they welcomed the “ambition” of the targets and would be working with “key organisations in Yorkshire” to help formulate their response to the consultation.
Once confirmed a spokesperson said the targets “will form an integral part of our business plan for the next five years and beyond”.
Completely separating sewage and rainwater systems to remove the need for storm overflows would cost £350bn to £600bn, according to the Government.
As well as pushing up water bills for consumers, it would be likely to cause major disruption as they are dug up.
Building extra storage to capture excess water during heavy rainfall is estimated to cost between £160bn and £240bn.
The Government said they expected water firms to accelerate the timelines set out in the Storm Overflows Discharge Reduction Plan “wherever possible while preventing unnecessary costs for consumers.”