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When there is really high rainfall, the waste water treatment works (WwTW) get overloaded by the amount of liquid. The infrastructure is designed to deal with a 'usual' amount of wastewater from the combined sources - from sinks, toilets, drains and rain. In theory, the heavy rains mean the treatment works get overloaded and so to deal with this pressure they are allowed to open to release the excess fluid so that they don't back up and overflow. Therefore, in heavy rain events i.e. storms, the WwTW release untreated waste water into our rivers to cope with the pressure.
However, because the WwTW are already beyond capacity in most cases, they are releasing untreated water even when there is low or no rainfall!
13 Wastewater Treatment Works recorded raw sewage spilling into our rivers across the Catchment in 2022. The other 6 treatment works don't have Event Duration Monitors Installed so could be releasing untreated sewage without us knowing...
Downstream of Church Hanborough sewage treatment works, feacal (poo) indicator bacteria - E.coli - was 50 times greater than the level for safe bathing in November 2022!
Thames Water have provided a map of the catchment with their Even Duration Monitors (EDMs) which monitor when and for how long the WwTW are releasing untreated waste water (which includes raw sewage). You can view the map by clicking the button below.
Thames Water EDM map"This map provides near real-time information about storm overflow activity, as indicated by event duration monitoring (EDM). You can use the map to see if our EDM monitors indicate: 1) which overflows are currently discharging into a watercourse 2) the date and time of the last recorded discharge." Thames Water
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The Evenlode Catchment Partnership has set up a Scheme to enable farmers and landowners to create wetland habitat on their land.
Earthwatch have deployed 4 RS Hydro Proteus Sondes in the Evenlode Catchment, in rivers upstream and downstream of twoSewage Treatment Works. These are automated, real-time water quality sensors. 10 water quality parameters are being measured at 15 minute intervals. Three of these parameters will be presented in this page.
The high frequency data produced by the Sondes is being used to compare the water quality upstream and downstream of SewageTreatment Works to investigate chronic pollution. This site-specific work is supporting the Citizen Science and Environment Agency monitoring that is being undertaken at a wider scale across the catchment.
Temperature
Temperature affects biological and physical processes, so it provides important context for the other measurements. For example, warmer water can hold a greater amount of dissolved oxygen than colder water, and conductance also increases with temperature. Water temperature would be expected to be warmer in the daytime than at night, and warmer in the summer than in the winter. Temperature of wastewater effluent is often warmer than water in rivers.
Dissolved Oxygen
Dissolved oxygen is the amount of oxygen present in the water that is available to support aquatic life. Photosynthesis creates oxygen, as carbon dioxide is converted into sugars using sunlight, so dissolved oxygen will be higher during the daytime, especially in the summer months when plants and algae are most active. Dissolved oxygen is reduced when plant and organic matter is being decomposed by bacteria.
Specific Conductivity
This is the ability of the water to pass an electrical current. Salts, minerals, and inorganic substances help water to conduct electricity, while organic substances reduce conductivity. Conductance is usually defined by geology. Since the Evenlode rises from underlying limestone, a relatively high conductance is expected because limestone is easily dissolved in water. Large, sudden changes in conductivity usually indicate some kind of disturbance, such as sudden soil erosion or a pollution event.
You can view the data directly below or read our report with our analysis and comments
The Evenlode Catchment Partnership has set up a Scheme to enable farmers and landowners to create wetland habitat on their land.
The Evenlode Catchment Partnership has set up a Scheme to enable farmers and landowners to create wetland habitat on their land.
