Yorkshire Water has announced the departure of its chief executive, a day after the water supplier was given the lowest environmental rating by regulators.

Nicola Shaw has decided to step down after four-and-a-half years leading the business, the company said.

Nicola Medalova, a former National Grid executive, will join next week as chief executive-designate, before taking over the role in January.

Ms Shaw said there โ€œremains a huge amount of work to doโ€, but that the business is on โ€œstronger footing for delivery across all aspects of its workโ€.

She added: โ€œThis now feels like the right time to begin an orderly transition to the companyโ€™s next chapter.โ€

On Thursday, the Environment Agency (EA) said it had downgraded Yorkshire Waterโ€™s environmental rating from two stars out of four to one โ€“ the lowest possible rating.

Yorkshire Water was this week downgraded by the Environment Agency to the lowest possible rating (Alamy/PA)
Yorkshire Water was this week downgraded by the Environment Agency to the lowest possible rating (Alamy/PA)

This means it is classed as poorly performing and, alongside Southern Water, Thames Water and South West Water which also got one-star ratings, was automatically blocked from giving out bonuses to bosses under new rules introduced last year.

The company, which serves more than five million people in the Yorkshire region, had 335 pollution incidents in 2025, including 13 that were serious, the EA found.

It was fined ยฃ1.2 million in total last year over pollution incidents.

Yorkshire Water has also previously come under scrutiny for payments to Ms Shaw worth ยฃ1.3 million between 2023 and 2025 made through the Jersey-incorporated company Kelda Holdings.

The company stressed at the time the payments were made by shareholders rather than bill payers.

Ms Medalova said: โ€œYorkshire Water faces huge challenges but also great opportunities for continued improvement, and I look forward to working with Nicola Shaw, the leadership team and colleagues across the business as I get up to speed.โ€

She pledged to have a โ€œrelentless focusโ€ on delivering โ€œfor customers, communities and the environmentโ€.