Work has started on investing over £60 million in Ilkley and Addingham to improve water quality in the River Wharfe and reduce discharges from storm overflows during heavy rain. Additionally, we’re investing almost £1 million to secure the March Ghyll reservoir water supply for future generations.
We’ll deliver major benefits for people and nature, including a cleaner and extended designated bathing water status stretch of the river Wharfe. Through our investment, we’re creating new opportunities for outdoor exercise and natural environments, where nature can thrive.
We’ve been developing plans for the various schemes around Ilkley for a while, focusing on nature-based solutions where possible, and we’re pleased to already be on site, as we begin to deliver over this five-year investment period.
As we move forward, we’ll keep the local communities informed, and work with the relevant authorities to keep any disruption to a minimum.
Ilkley Inland Bathing Water Improvement Scheme:
We’re upgrading the combined sewer overflows (CSOs) and sewage treatment works at the River Wharfe, Ilkley. This includes sites around 5km upstreaming from designated bathing areas. The sites we’re upgrading include:
- Low Mill Lane CSO
- Addingham SPS CSO
- Bridge Lane CSO
- Rivadale CSO
- Middleton SPS CSO
- Ilkley Sewage Treatment Works
The project aims to reduce the number and volume of discharges from the CSO, helping to improve water quality in the river Wharfe. Our upgrades will more than double the wastewater treatment capacity of the sewage treatment works, dramatically reducing the frequency and duration of storm overflows into the river Wharfe around the bathing water and improving water quality.
Once completed, the additional storage will hold excess wastewater flows during periods of prolonged and heavy rainfall, reducing discharges from the overflows into the Wharfe. The stored storm water will then be released to Ilkley wastewater treatment works once the rainfall event has passed, and after incoming flows have reduced.
Ilkley Integrated Constructed Wetland (ICW):
We’re creating a brand new natural wetland treatment site, which will help do the finishing touches in our wastewater cleaning process in Ilkley.
Once wastewater has been through the upgraded Ilkley wastewater treatment works, it will be transferred across the river Wharfe through a newly constructed sewer, to a brand new integrated constructed wetland for tertiary treatment. Water will then pass through six interconnected ponds, allowing further treatment through a wide range of carefully selected wetland plants and without the need for chemicals or powered equipment, before it is returned to the environment from a new outfall.
The wetland will provide a biodiversity net gain and will be accessible to the public. We plan to make the site a calm and relaxing place for local people to unwind, and we’re looking forward to providing enhancements which allow people to make the most of this new nature hotspot.
March Ghyll Reservoir Bank Stabilisation:
The March Ghyll reservoir bank stabilisation project involves transporting large quantities of rock material up Hunger Hill to stabilise the reservoir banks. This work is crucial for ensuring the structural integrity of the reservoir and to prevent bank collapses, thereby protecting the local water supply and surrounding environment.
As a result of these works, there will be some disruption around the Hunger Hill area from May 2025, through to Winter 2025. To improve the reservoir, we need to transport aggregate weighing 7,800 tonnes. This is the same as 1,560 African elephants, or the water in three Olympic-sized swimming pools!
We thank all residents and visitors for their understanding while we carry out this vital work.
Through all these schemes, we’re committed to improving river water quality and reducing storm overflow discharges, and these are a major part of our £800 million investment in Yorkshire this year.
We’re delighted those upgrades to the sewage treatment works and our new wetland, which will all be completed in Summer 2026, will meet UK Government targets of one discharge per bathing water season nine years ahead of the 2035 deadline.
We know how important it is to our customers and for the environment that we tackle the number of discharges from storm overflows across our region, and we’re committed to reducing their operation.
Crucially, all these projects will significantly improve the water quality in the River Wharfe, allowing us to Do Right by Yorkshire!
Will the ICW smell?
The flow that goes to the new ICW will be treated sewage – the flow will have been through the full, standard sewage treatment process at the sewage treatment works and instead of being discharged to the Wharfe at that point, will go through the ICW which will provide an additional level of treatment. This means that the flow entering the Wharfe at the new discharge point will be of a better quality, above and beyond what we “have to” treat as per regulations. The ICW is not being designed to take any raw sewage and there should therefore be no unpleasant odour. It is taking the treated flow that currently enters the Wharfe at the discharge point adjacent to the STW.
What if someone falls into the ICW?
All of the cells within the ICW will have a fence around them. They are also designed to have a 30 degree slope so that is anyone did enter, they can easily get out. Signage will be present to request that people do not go over the fence and enter the water.
Will the existing public footpath still be there?
There will be a public right of way through the ICW area. We have designed this using the well-trodden path which cuts diagonally across the field, rather than the documented PROW which currently goes across the top of the field.
You shouldn’t be putting raw sewage into the river at all.
We do not dump or pump raw sewage into the Wharfe, or any watercourse. In times of heavy rainfall, all water companies are permitted by the Environment Agency (with conditions) to spill over into a watercourse (also knows as a CSO). Heavy rain can cause our sewerage network to become full, and if we do not spill some of the flow within network, it will back up and come out elsewhere, likely via a manhole onto the street or into someone’s kitchen or cellar. By increasing storage vastly within the Ilkley area, we are increasing out network capacity, thus reducing the risk of excess sewage spilling into the Wharfe.
When all the work is finished, will the Wharfe be an Excellent bathing water?
The classifications of bathing waters are based on the average of weekly bacteria samples (sampling carried out by the Environment Agency).
The EA sample once a week between May and September, and at the end of that sample season, they average the weekly results. This average is what defines the classification for each bathing water site. Currently, the Wharfe at Ilkley is classed as Poor.
The work we are doing in the area is designed to greatly reduce any impact from us into the Wharfe in the area, and as such we hope that the classification will improve.
However, there are many other factors in addition to sewage that can and do impact on bathing water quality such as agriculture, sewer misconnections, wildlife, road run-off etc.
We will continue to work in partnership with other stakeholders and organisations to reduce the impacts from other sources with the overall aim of improving the health and subsequent classifications of the Wharfe.