Rivers in the north of England are bearing the brunt of the sewage pollution crisis, analysis by the Guardian reveals, with the region’s waters experiencing the highest rates of waste discharge in the country. Storm overflows around the Irwell valley, where the rivers Croal and Irwell run through to Manchester, discharged raw sewage 12,000 times in 2023 — the highest rate of all English rivers when accounting for length, at 95 spills per mile. It comes as new data reveals that 2023 was the worst year on record for storm water pollution, with overflows spilling raw sewage into England’s rivers and seas for 3.6m hours. You can check your local rivers using the tool below, which shows spills across England’s river basins. The Guardian’s analysis is based on Environment Agency data released on Wednesday, which details the number of times storm overflows discharged across England in 2023. Overflows should only be used during exceptional weather events, such as major storms. But a lack of investment means there is a lack of capacity at treatment works and a failure to maintain assets, both of which contribute to the level of sewage discharges. Regulators are investigating widespread suspected illegal sewage dumping, which takes place in breach of the permit conditions. The River Irwell is a popular waterway for rowers and the scene of several regattas in summer — but the 2023 overflow data shows its waters and surrounding catchment area is now the worst sewage dumping ground in England. Second worst for spills was the River Darwen, near Blackburn and Preston, where there were 3,145 sewage discharges from nearby overflows in 2023. Relative to the length of its waterways, this was equivalent to 83 spills per mile. Just one river in the south of England features in the worst 10 rivers identified by the Guardian — the River Avon, as it makes its way through Bath and Bristol. The river suffered 6,573 sewage spills in 2023, or 74 spills per mile, making it the third most polluted in England. Also worst for sewage spills was the River Calder near Huddersfield, the Aire near Bradford and the lower section of the Tyne around Newcastle and Sunderland, the Guardian’s analysis of Environment Agency data has found. Water companies have faced a barrage of criticism in the wake of the data, which shows sewage spillages have more than doubled on 2022. Several of the rivers highlighted by the Guardian have experienced large rises in sewage spills. Sewage spills rose from 7,168 in 2022 to 11,974 in 2023 on the Croal and Irwell and some of their nearby tributaries, while spills rose from 3,966 to 6,573 in the stretch of the River Avon that runs through Bath and Bristol. Industry figures have pointed to the heavy rainfall over the autumn and winter that put huge pressure on the sewage system, and have stressed they are investing to upgrade the water network. But campaigners say the use of the storm overflows has become routine after years of underinvestment, and that the levels of spilling far exceeds what might be expected from just relieving the strain of extreme weather. Water UK, the trade association for water companies, said: “These results are unacceptable and demonstrate exactly why we urgently need regulatory approval to upgrade our system so it can better cope with the weather. “We have a plan to sort this out by tripling investment which will cut spills by 40% by 2030 – more than double the government’s target.” We’d like to hear about your local river and the environmental issues affecting it. You can get in touch with us here. Methodology Storm overflow data is sourced from the Environment Agency’s (EA) event duration monitoring dataset and covers 2023. This data is collected by water companies using equipment attached to overflows and then submitted to the EA on an annual basis. It measures the number of times an overflow has discharged each year, though provides no indication of the volume of the discharge or its content. River geographies and catchment areas sourced from the EA’s river catchment data explorer, produced from its work under the water framework directive. We have analysed rivers at an operational catchment level, which combines rivers and their tributaries into wider river basins. We have then used a geospatial analysis to locate all the overflow spills that lie within each of these basins, and summed up spills to produce a total for 2023. River length figures have been calculated by the Guardian using the map information from EA’s catchment data, and are approximate only. We have used this estimation to calculate spills per mile for each river basins, which underpins our ranking of rivers.