Work at a reservoir which has been fully drained for months is nearing completion as water is slowly flowing back in.

The Canal & River Trust is now allowing Welsh Harp Reservoir to begin its refill process after it was emptied in December 2023.

The equivalent of 400 Olympic-sized swimming pools were drained and 100,000 fish were rehomed so tonnes of litter could be cleared, the reservoir’s sluices repaired and the Valve House Tower repainted.

According to the trust, water will be slowly making its way back to the site and it should be refilled by the end of May.

New nesting areas and island habitats for birds will also be created.

Times Series: The drained Welsh Harp ReservoirThe drained Welsh Harp Reservoir (Image: Joseph Reaidi)

Laura Chow, head of charities at People’s Postcode Lottery, which funded the project, said: “The teams involved in the Welsh Harp Brent Reservoir project have put in a mammoth effort draining it, rescuing wildlife and removing the tonnes of litter.

“Welsh Harp Brent Reservoir is a little slice of countryside and serenity in the city, so I’m delighted the next stage of works in allowing it to be refilled is underway and money raised by our players is helping to make this possible.”

It was originally anticipated that the reservoir would be refilled by the end of February, but the Canal & River Trust admitted earlier this year it would take longer than expected.

The operation has been hit by a series of delays. The reservoir was meant to be emptied in November 2023, but this did not start until December.

Then extreme weather events and the “unprecedented" number of fish meant refilling could not begin in February.

During its clean-up, many fascinating objects were found including Second World War munitions, a machete and even a flurry of religious offerings.

But while much of the reservoir has been cleared, the Brent & Kilburn Times saw that there were still obvious bits of rubbish left behind on Sunday (April 14) – including rusted cans and dirty plastic bottles.

Times Series: Rusted cans and dirty bottles at Welsh Harp ReservoirRusted cans and dirty bottles at Welsh Harp Reservoir (Image: Joseph Reaidi)

Ros Daniels, the Canal & River Trust’s London and South East director, said: “Unfortunately the succession of winter storms and high rainfall levels we’ve experienced over the winter did delay the repairs and improvements, but we’ve worked closely with Natural England to minimise the impact on wildlife. 

“We’re now looking forward to welcoming back Londoners and wildlife to this special oasis and, depending on how much rain we get, expect the reservoir to have re-filled by the end of May.”