Event Duration Monitoring - Storm Overflows - 2021 (England and Wales)

This Event Duration Monitoring dataset relates to the performance of storm overflows in England and Wales. The Water and Sewerage Companies (WASCs) in England provide this regulatory return to the Environment Agency each year to fulfil their permitted conditions to discharge from these storm overflows under the Environmental Permitting Regulations. The English data were downloaded from data.gov.uk (accessed 31st March 2022) and the Welsh data were provided on request by Dwr Cymru / Welsh Water, though they also publish their data as a list (without grid references). For England the dataset also includes reasons why event duration monitors may have provided information for <90% of the relevant return period, and why an overflow may have high spill counts in that period. What doesn't this dataset show? There are a significant but unknown number of storm overflows which are not included in this dataset because the WASCs and the Environment Agency don't know where they are within the sewer network. If you spot signs of sewage pollution please report this to the Environment Agency on 0800 80 70 60 so that these unmapped discharges can be pinpointed. Emergency overflows in England are not included in this dataset as the Environment Agency only require storm overflows to be included in the EDM returns, though some WASCs do record this information. Emergency overflows do have permits but these are for use in the event of mechanical issues, for example pump failure. Dwr Cymru / Welsh Water have included some emergency overflows in their dataset so we have included these in this layer. We do publish the emergency overflows for England in the consented discharges dataset, but we don't have spill duration data for them. You can find out more about environmental permits for storm and emergency overflows for England here and Wales here. Quality Control The Rivers Trust has endeavoured to clean, check and interpret the data, but cannot be held responsible for any missing or inaccurate data. Points in the sea may be long-sea outfalls or they may be errors in the data. Water companies, citizen scientists and map users are welcome to contact us to notify any known data errors on specific overflows and we will flag these in the map popups and pass on to the Environment Agency. We are providing feedback to the Defra storm overflows taskforce about how to improve transparency around sewer storm overflows, and would welcome feedback and suggestions. [e-mail]