Water Quality and Advocacy

None of the 18 waterbodies in the Evenlode Catchment currently achieve 'good' ecological status (under the Water Framework Directive)
Physically, the natural course of the catchment waterways has been modified which can damage the river habitat and increase flooding. There is also a huge issue with pollution in the water. Pollution usually stems from agricultural run-off and/or from sewage outlets. In the Evenlode, the data points to local sewage treatment works as a major source of pollution. You can listen to the Stop all the Locks poem to hear about the pollution the rivers face, or scroll on for more information.

"The Evenlode waters used to be crystal clear, then, one summer it seemed, they turned to look like oxtail soup. It is still obvious something is very wrong"

John Pratt - Catchment Champion for the ECP

How untreated sewage enters our river systems

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!

Top of the Plops!

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!

Check to see where is releasing raw sewage in real time

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

How you can help - Thank you for visiting this page!

Help from your own home

Join Us - Come and see us at events  

Report a Pollution Incident

Help us Campaign


Farming & Preventing Run-off  

Town & Village Planning

The Evenlode Catchment Partnership has set up a Scheme to enable farmers and landowners to create wetland habitat on their land.

Sonde Data Overview

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.

Understanding the Data - Water Quality Parameters

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.

Sondes Report

You can view the data directly below or read our report with our analysis and comments


Chipping Norton

Thanks to RS Hydro for the Sonde Data Charts

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.

Copyright © 2022 Wild Oxfordshire. All rights reserved. | Our Privacy Policy | Terms & Conditions | site by im23