THERE has been an astounding change in West Yorkshire's rivers after a clean-up, says a watchdog.
The Environment Agency also says wildlife is benefiting from the cleaner rivers.
The agency, which celebrates its 10th anniversary this week, has been changing the quality of the environment across the region.
Much of the area has been blighted by an industrial past which left a legacy of pollution and contamination.
The agency says that in Huddersfield river waters are now clearer and contaminated land has been cleaned up.
In the mid-1990s the River Calder was classified as `poor'. It is now `fairly good', due to tighter controls over what goes into the water.
It boasts a healthy selection of wildlife, including otters and also salmon and sea trout, both species that swim upstream to spawn.
The agency has also reported a successful clean-up at an old tar distillery site in Mirfield.
Tar leaking into the Calder was a threat to health and wildlife.
In 2001 the agency built a £580,000 steel retaining wall, with pipes to collect the waste and dispose of it.
An agency spokesman said: "What we have achieved in the past 10 years in terms of creating a cleaner and safer environment across West Yorkshire has been little short of astounding.
"Houses and leisure developments stand on what was contaminated land. We also have some of the cleanest rivers in the country."