Thousands of fish gasped their last dying breath last week after torrential rainwater washed a lethal cocktail of pollutants into the River Lee sending oxygen levels crashing to zero. Video courtesy of Robin Grey, www.robingrey.com.

Hackney Gazette: Dead fish in the river Lea.Dead fish in the river Lea. (Image: Archant)

Hackney Gazette: Hackney residents Tim Taylor, left, Dave Barlow, and Dee O'Connor are angry at the fish deaths.Hackney residents Tim Taylor, left, Dave Barlow, and Dee O'Connor are angry at the fish deaths. (Image: Archant)

The shocking scene was witnessed Tuesday morning after the previous night’s heavy thunderstorms, following a two week dry spell.

Hackney Gazette: Dead fish - photo taken in the Olympic Park by Theo Thomas from Thames 21Dead fish - photo taken in the Olympic Park by Theo Thomas from Thames 21 (Image: Archant)

The Environment Agency confirmed the rain had washed oils, heavy metals, dirt and dust which had built up on the roads into the Lee and its tributaries, leaving the pollutants to dissolve the little oxygen that remained in the water.

Theo Thomas who runs campaign group Thames21’s Love the Lea Campaign said the pollution had pushed the river over the edge.

“The Lea is a river at risk, is a very polluted river all year round and on Monday it was teetering on the brink,” he said.

“During hot weather water holds less oxygen anyway. But fish were not dying earlier in the week, it’s the pollution that killed the fish.

Those behind the campaign believe the status quo must change, as an increasing number of vehicles on the roads mean more pollution is being washed into the rivers.

“There’s an attempt to say this is just the hot weather, that sets the conditions up very dangerously and precariously if it hadn’t have rained and washed in the pollution we wouldn’t have seen the fish die,” said Mr Thomas.

“This is the water we use to draw out drinking water from, it seems to be a nonsense to put all this pollution into the source of our drinking in the first place.”

Environment Agency fisheries officers worked throughout Tuesday night aerating the Lower River Lee at Three Mills Boatyard, and continued to monitor improving oxygen levels which rose to around 25 per cent.

But Mr Thomas said the action is just a “sticking plaster” and preventative action must be taken.

The Love the Lea campaign is calling for the creation of mini-wetlands, gravel trenches and interceptors which would all remove pollutants from the water before they are able to enter rivers.

They also say more reed beds and aquatic plants would oxygenate the water and give fish a refuge, and that car parks could intercept run-off by turning unused corners into mini wetlands.

Thames 21 Volunteer Damian Rafferty who reported the dead fish to the authorities believes the River Lee is “on its last gasp”.

He said: “The Lee urgently needs an action plan and a lot less blame shifting or it will be utterly barren by the time West Ham move into their new stadium.

“If the gulls weren’t gorging on them, there would be a slick of dead fish across the river from side to side.”

Thames 21 is calling on Transport for London (TfL), which operates the major roads in the capital to ensure pollution is intercepted before it reaches the rivers, as already happens on many roads operated by the Highways Agency.