Several Norfolk Broads have been given a clean bill of ecological health after more than a century of stagnation.
Clear water bays at Barton Broad in Norfolk
Damage to the Broads was blamed on sewage dumping and chemical run off from agricultural land.
A joint report by English Nature and the Broads Authority has revealed that nine per cent of open water is now fully restored.
Another 50% is on the way to recovery and should be in a 'favourable' condition by 2010.
The report identifies broads at Upton, Martham and Buckenham as waterways now enjoying full ecological health.
'Time and money'
At Barton Broad a massive restoration programme has taken 25 years to cut by 80% the effects of chemical nutrients which cloud the water and kill of plant and aquatic life.
Andrea Kelly, Broads Authority conservation officer, said: "There has been a major effort over the past 25 years to restore the lakes within the Broads and the rewards are now being reaped.
"But there is still some way to go and full recovery is likely to take some time and investment."
At the beginning of the 20th century the lakes and rivers within the Broads consisted of crystal clear water with a wide variety of water plants.
However, some 50 years later there was a catastrophic decline, with the loss of plant beds.
The fishery declined and species such as the bittern and otter, dependent upon a healthy water environment, were lost.