Dozens of fish in the River Colne have been killed after a pollution incident during the thunderstorm last week.

Anglers have reported crayfish dead in traps, roach and pike dead - but the quantity is yet to be confirmed - and cloudy foul smelling water.

Fish have been affected throughout the Watford and Three Rivers stretch of the river, with particular problems reported in Carpenders Park and Oxhey Park.

In a statement, the Environment Agency said they were continuing to investigate the cause and had deployed aerators to raise oxygen levels in the river.

It said: "On Saturday, a member of the public alerted us to fish in distress on the River Colne.

"Our Environment Agency officers responded to this and saw approximately 50 dead fish and others in distress.

"We have deployed aerators to raise oxygen levels in the river and we will continue to monitor and respond.

"Water quality results suggest low dissolved oxygen levels are the cause, and our investigation will continue.

"Extended periods of hot weather with low rainfall or storms can be deadly for fish."

Visitors to Oxhey Park and Riverside said the sight was "very distressing".

Jason Chapman said there was a smell of rotting fish in Oxhey Park and dead animals caught up in the reeds on the river bank.

He said: "I'm a regular walker through Oxhey Park and all the fish and rats in the river are dead and caught up in reeds and on the banks.

"Very distressing for children to see and smell rotting fish and a number of the fish have been half eaten by crows and dropped on to the path. There must be something in the water."

Park user Fiona O'Toole said: "All the fish in the river along the side of Oxhey Park and Riverside are dead.

"The Environment Agency have been informed. A local man will attempt to clear them in the next few days. Nice park shame about the river."

Should local residents spot anything of further concern it can be reported to the Environment Agency via their 24 hour incident hotline on 0800 80 70 60.