Yorkshire Water is progressing work on more projects in its £1.5 billion Yorkshire-wide programme to reduce the frequency and volume of discharges from combined storm overflows (CSO) into watercourses.

Discharges from storm overflows in Yorkshire decreased by 24.5% in 2025, when compared with the previous 12 months.

Last week the water company started begun conducting ground investigations on The Stray. The boreholes will be 20cm wide and 30m deep holes drilled into the ground to help understand ground conditions and monitor groundwater levels. Contract partners Ward and Burke will drill three boreholes on the area of grass between Montpellier Hill and the Esplanade over the course of six weeks.

The information gathered will help Yorkshire Water decide the most effective and safe way of reducing discharges into Oak Beck from the network.

Athif Khan, project manager at Yorkshire Water, said:

"Our storm overflows are discharging more than we, and our customers, would like, and we're making good progress in bringing the frequency and duration of those discharges down. Last year, we saw a 24.5% reduction in discharges following the investments we've been making.

"These boreholes are the next step in our plans to reduce discharges into Oak Beck and improve our impact on the environment. We understand how important The Stray is for our customers in Harrogate, and we'll do everything we can to keep disruption to a minimum. Once completed, we will return The Stray to its current condition. We thank everyone in advance for their patience and understanding.”

Once the investigations are complete, the boreholes will be backfilled, the area fully reinstated, and the data gathered from the survey will be used to aid the development of the best solution to reduce discharges into the beck. Prior to the boreholes being drilled, ecology and arboricultural surveys have been undertaken.

Yorkshire Water currently has a number of storm overflow projects in delivery across York, Bradford, Leeds, Sheffield, Rotherham and parts of North Yorkshire.

Work is also underway on a project to reduce the frequency and volume of discharges from a combined storm overflow (CSO) in Crambe into a tributary of the river Derwent.

The work forms part of the utility's £1.5bn drive to bring down the number of discharges across the county.

Contract partners at OCU will separate surface water from the existing combined sewer network, which carries both rain and wastewater, in order to reduce overall flow in the system. This means that Crambe CSO, which operates as a relief valve for the combined system when it is over capacity due to heavy rainfall, will be much less likely to operate.

A new surface water sewer will be installed in parallel to the combined network, alongside four gullies to improve drainage into it. Three further gullies, which currently drain surface water into the combined system, will also be diverted into the new sewer.

The work is expected to complete in October.

Qasim Elahi, project manager at Yorkshire Water, said:

"We're making good progress with the Crambe project, which, when complete, will reduce the number of discharges into the receiving watercourse – a tributary of the River Derwent. Our storm overflows are operating more than we, and our customers would like, so we're making improvements across 450 overflows by 2030."

The work at Crambe CSO marks eight storm overflow projects currently underway across North Yorkshire, with others taking place in Malham, Hebden, Wass, Snape, Myton-on-Swale, Great Barugh, and Weeton.

Discharges from storm overflows in Yorkshire decreased by 24.5% in 2025, when compared with the previous 12 months.

Storm overflows are designed to act as a relief valve for the combined sewer network, which carries both wastewater and surface water, during periods of heavy or prolonged rainfall. They discharge when the system is at capacity to prevent flows backing up and flooding homes and gardens.

Across Yorkshire, the need for storm overflows to operate will be reduced by:

Building new surface water sewers, to separate surface water and wastewater so that wastewater networks aren’t impacted by bad weather

Installing underground storage tanks, to build additional capacity into the network

Implementing nature-based solutions, to build additional capacity into the network

Implementing sustainable drainage systems, to slow the flow of surface water into the combined network

Lining combined sewer networks, to reduce rainwater and groundwater infiltration.