Here's how Northampton Washlands reservoir works and when officials decide to open the floodgates near Billing Aquadrome

Last week, Northampton was hit with a series of yellow and amber weather warnings as heavy rain and storms battered the town over six days.

Homes were flooded, cars trapped, and the River Nene burst its banks, while Billing Aquadrome eventually succumbed to the rising waters after initial resistance. By Tuesday afternoon, the Environment Agency had warned the site would flood—and it did.

Specialist water rescue teams helped 43 people escape the rising floodwaters, according to Northamptonshire Fire and Rescue Service (NFRS). The council provided emergency accommodation at Lings Forum Leisure Centre for 52 people and 22 dogs.

Speaking to Chronicle and Echo, Ben Thorley from the Environment Agency EA) explained how water storage works at Northampton Washlands.

He said: “Northampton Washlands is a large flood storage reservoir where we store about 2.4 million cubic metres or a million tonnes of water when there is flooding in Northampton. We use the reservoir to control the amount of water going downstream (towards Billing Aquadrome), but when the reservoir is full, that’s the point where we no longer have that ability to control the volume going downstream, and that’s when the floodplain downstream needs to be used to store all that excess flood water, and unfortunately properties do get flooded downstream and residents [are] affected in those areas.”

After the 1998 floods, some defences were built in the centre of town, but Mr Thorley says that intense rainfall brings additional challenges. He said: “When we have very intense rainfall, the surface water that affects the town can’t get into the river. So often the river has plenty of capacity to take that water, but the water can’t get through the drainage networks into the river, so we have a mixture of surface water flooding that affects Northampton as well as river flooding that can affect Northampton.”

The reservoir was at 97 percent capacity last week when the floods hit. Mr Thorley said: “Once the reservoir is full, effectively we have to use this structure to release more water downstream, because we effectively have more water coming into the reservoir area than we can hold. It’s like a large bathtub beside the river, we use it to store water, but once the bath is full, if there’s more water coming into the area, then that water has to be drained from the area and discharged downstream. We contain as much as we can for as long as we can, but it gets to a point where there’s more water than we can manage.”

He added: “We’ve done all we can to protect residents downstream and upstream. But it gets to a point where there’s no more ability to store water, and the level downstream has to increase.”

He also acknowledged that no flood measures can offer complete protection. “We can never stop every single flood. We do all we can to reduce the impact of flooding. But you can never guarantee a community won’t flood,” he said.