Environment Agency News Release
A NETWORK of mini dams and underwater passages could be built in the River Don to help fish recover from the effects of a freak pollution accident last year, a minister has revealed. Environment minister Ben Bradshaw said "fish passes" may be installed in the river to allow fish to migrate upstream to restock areas of the river affected by the incident.
They help fish to move more quickly up the river by bypassing structures like locks and weirs.
Thousands of fish were killed last July when a period of dry weather led to reduced water levels and a drop in oxygen.
This was followed by heavy rainfall and caused sewage from storm overflows to enter the river in Sheffield and Rotherham.
Anglers were horrified to discover hundreds of fish carcasses, some two feet long, along the river banks.
Under a huge restocking programme 10,000 fish, including roach, bream and dace, were brought from the Environment Agency's Calverton Fish Farm at Nottingham and released into the water in Sheffield city centre as well as at Kilnhurst, Conisbrough and Thrybergh.
But in a statement to MPs, Mr Bradshaw said a recovery plan for the Don may also include making modifications to the river to allow current fish stocks to move around the river more easily.
He said: "Stocking is a useful fisheries management tool for developing and recovering rivers, but only one part of the recovery process.
"The river will slowly recover naturally as fish from upstream and downstream redistribute, but we are considering what the river needs to improve fish stocks now and protect against future storm sewage incidents.
"Fish passes, for example, may be installed, according to need, in order to allow stocks unaffected by the pollution to migrate upstream. A recovery plan for the river is being finalised."
The environment agency said fish passes are already planned for Sprotbrough Weir in Doncaster and Ickles Weir at Rotherham.
Fish passes allow fish to travel upstream by slowing the speed and velocity of the river.
The most common kind of fish pass is called 'pool and weir' and uses a series of small dams and pools to create a long, sloping channel. To head upstream, fish must jump from pool to pool.
Mr Bradshaw gave the written answer after a question from Sheffield Hallam MP Nick Clegg.
The Liberal Democrat MP said: "I am pleased the Don appears to be slowly but surely recovering from the shock of last summer. However, it is clear the Government needs to do more to ensure the water quality will support fish life and to protect our ecosystem from further overflow pollution."